fix(fleet): activate the lease broker at install/start, place units through symlinks safely, refuse doomed launches (#1292)

Wall 6: no documented path ever enabled or started the shipped
mosaic-lease-broker.service — every gated runtime died ~4s in at lease
registration while fleet start reported rc0, and a broker not in the
reconciler plan could not be reported as drifted.

Activation lands in the control plane, not the launcher:

- fleet install places ALL FOUR units through placeUnitFile — a placement
  helper that unlinks any by-path-enable symlink at the destination
  BEFORE copying (Node copyFile follows the link and overwrites the SEED
  template; measured on a throwaway systemd user instance 2026-08-17,
  with both cp and fs.copyFile), removes a stale wants-symlink pointing
  outside the active dir (readlink — readFile returns the target's
  content, not the link path), then copies and daemon-reloads. The same
  measurement showed systemctl enable <name> does NOT rewrite an existing
  by-path wants-symlink — reconciliation must be explicit. Idempotent:
  second install on by-path residue converges to the identical state.
  Until now the copy block named three units and omitted the broker, and
  the residue set / copy set were disjoint only by accident (fomo-lin
  survived copy-through because its one symlink was the one unit not
  copied); adding the broker made them intersect on first run. See the
  SET-INDEPENDENCE note on the helper before adding a fifth unit.
- enableFleetUnits enables the broker first, alongside the holder.
- fleet start / reconciler start the broker BEFORE any holder/agent
  lifecycle effect, then RE-CHECK the socket (not unit state) and exit
  nonzero with a named code if it did not appear. Re-probed on every
  invocation — a RemainAfterExit=yes dead-looking-active unit can never
  make retry look like repair (the sticky-retry check).
- The reconciler plan carries broker {unitInstalled, socketPresent} as a
  first-class member; the socket is the signal (enabled-but-dead units
  report socketPresent=false).
- start-agent-session.sh preflights the broker socket BEFORE any tmux
  effect (moved ahead of the ownership probe): absent -> exit 75
  (EX_TEMPFAIL), named refusal with socket path and remedy, no doomed
  pane. The agent@ unit is Type=oneshot with no Restart=, so the message
  survives instead of looping. The preflight detects and refuses; it
  never starts the broker.
- mosaic doctor's lease check names one convention-neutral remedy:
  'mosaic fleet install (it reconciles either enable convention)' —
  written from the measurement; teaching a manual systemctl line could
  leave a host with competing wants-symlinks.

Tests: fleet-place-unit.spec.ts (8: clean-host negative control,
by-path residue -> seed bytes AND mtime unchanged [the finding-2 check],
wants-residue cleared, idempotence single + double-install convergence);
fleet.spec.ts broker-first enable ordering, refused start emits no
holder/agent calls, second-start re-probe; reconciler broker plan member
(enabled-but-dead shape) + broker-before-agent ordering in both command
and apply paths; test-agent-session-broker-preflight.sh (CI-fit: fake
tmux, real unix socket at a short /tmp path — AF_UNIX caps at 108 bytes,
hermetic env; absent -> exit 75 + no tmux session, live socket passes,
explicit env wins, --stop not fenced). 1563/1563 vitest, lint, root
build 25/25, root typecheck 45/45.

Sabotage controls: placement unlink removed -> exactly the seed-integrity
test reddens (1/8); socket re-check disabled -> exactly the two preflight
specs redden; shell preflight removed -> the bash suite reddens (6 FAIL
assertions, rc=1). All restored byte-identically (sha256-verified), all
green again.

Test 6 (greenfield 1124, seat alive 2min + second fleet start) runs on
sandbox after daphne's baseline, coordinated with fred.

Note: the preflight uses exit 75 measured against the unit's Restart=
policy (oneshot, none) — no restart loop.

apps/web/src/components/freshness/freshness-notices.tsx

@@ -1,110 +0,0 @@
-'use client';
-
-import type { ReactElement } from 'react';
-import { formatAge, type FreshnessLabel } from '@/lib/freshness/model';
-
-/**
- * Rendering rules for non-current freshness states (RI-5-001).
- *
- * - `unavailable` renders an explicit failure panel — never an empty
- *   healthy collection.
- * - `stale` may render last-known data, but only under a visible label
- *   carrying source identity, snapshot version, and age.
- * - `partial` renders the verified parts plus an explicit list of what is
- *   missing.
- */
-
-interface RetryableNoticeProps {
-  readonly onRetry?: () => void;
-  readonly retryLabel?: string;
-}
-
-function RetryButton({ onRetry, retryLabel }: RetryableNoticeProps): ReactElement | null {
-  if (!onRetry) return null;
-  return (
-    <button
-      type="button"
-      onClick={onRetry}
-      className="mt-2 rounded-lg border border-surface-border px-3 py-1.5 text-xs transition-colors hover:border-gray-500"
-    >
-      {retryLabel ?? 'Retry'}
-    </button>
-  );
-}
-
-export interface UnavailableDataNoticeProps extends RetryableNoticeProps {
-  /** What is unavailable, e.g. "Tasks". */
-  readonly title: string;
-  /** Optional underlying failure detail (network message, invalidation reason). */
-  readonly detail?: string | null;
-}
-
-/** Explicit `unavailable` state. Never renders as an empty healthy collection. */
-export function UnavailableDataNotice({
-  title,
-  detail,
-  onRetry,
-  retryLabel,
-}: UnavailableDataNoticeProps): ReactElement {
-  return (
-    <div role="alert" className="rounded-lg border border-error/40 px-4 py-3 text-sm">
-      <p className="font-medium text-text-primary">{title} are unavailable</p>
-      <p className="mt-1 text-text-muted">
-        This is not an empty result — the data could not be verified from the gateway.
-        {detail ? ` ${detail}` : ''}
-      </p>
-      <RetryButton onRetry={onRetry} retryLabel={retryLabel} />
-    </div>
-  );
-}
-
-export interface StaleDataNoticeProps extends RetryableNoticeProps {
-  /** Provenance of the last-known snapshot being displayed. */
-  readonly label: FreshnessLabel;
-}
-
-/**
- * Situational-awareness banner for `stale` data: last-known data may render,
- * but visibly labeled with source identity, snapshot version, and age.
- */
-export function StaleDataNotice({
-  label,
-  onRetry,
-  retryLabel,
-}: StaleDataNoticeProps): ReactElement {
-  return (
-    <div role="status" className="rounded-lg border border-warning/40 px-4 py-3 text-sm">
-      <p className="font-medium text-warning">Showing last-known data — it may be out of date</p>
-      <p className="mt-1 text-xs text-text-muted">
-        Source {label.source} · snapshot v{label.version} · fetched{' '}
-        {formatAge(label.fetchedAt, Date.now())}. Verdicts derived from this data are unknown and
-        changes are disabled until it is revalidated.
-      </p>
-      <RetryButton onRetry={onRetry} retryLabel={retryLabel ?? 'Revalidate'} />
-    </div>
-  );
-}
-
-export interface PartialDataNoticeProps extends RetryableNoticeProps {
-  /** Display names of the sections whose collections are unavailable. */
-  readonly missing: readonly string[];
-}
-
-/** `partial` surface banner: verified parts render, missing parts are explicit. */
-export function PartialDataNotice({
-  missing,
-  onRetry,
-  retryLabel,
-}: PartialDataNoticeProps): ReactElement {
-  return (
-    <div role="status" className="rounded-lg border border-warning/40 px-4 py-3 text-sm">
-      <p className="font-medium text-warning">Some data could not be loaded</p>
-      <p className="mt-1 text-xs text-text-muted">
-        {missing.join(', ')} {missing.length === 1 ? 'is' : 'are'} unavailable — sections below show
-        an explicit unavailable state instead of an empty list. Derived verdicts remain unknown
-        until every collection is revalidated.
-      </p>
-      <RetryButton onRetry={onRetry} retryLabel={retryLabel ?? 'Revalidate'} />
-    </div>
-  );
-}

apps/web/src/lib/freshness/model.spec.ts

@@ -1,324 +0,0 @@
-import { describe, expect, it } from 'vitest';
-import type { Task } from '@/lib/types';
-import {
-  acceptSnapshot,
-  assertMutable,
-  canMutate,
-  combineFreshness,
-  computeDigest,
-  computeFreshness,
-  DEFAULT_FRESHNESS_POLICY,
-  formatAge,
-  type FreshSnapshot,
-  invalidationReasonLabels,
-  StaleMutationError,
-  UNKNOWN_VERDICT,
-  verdictValue,
-} from './model';
-import { validateProjectCollection, validateTaskCollection } from './validators';
-
-const NOW = 1_800_000_000_000;
-
-const policy = { ...DEFAULT_FRESHNESS_POLICY, staleAfterMs: 60_000 };
-
-const taskPayload: Task[] = [
-  {
-    id: 'task-1',
-    title: 'T1',
-    description: null,
-    status: 'not-started',
-    priority: 'high',
-    projectId: 'project-1',
-    missionId: null,
-    assignee: null,
-    tags: null,
-    dueDate: null,
-    metadata: null,
-    createdAt: '2026-08-01T00:00:00.000Z',
-    updatedAt: '2026-08-01T00:00:00.000Z',
-  },
-];
-
-function acceptedTaskSnapshot(
-  overrides: Partial<FreshSnapshot<typeof taskPayload>> = {},
-): FreshSnapshot<typeof taskPayload> {
-  const result = acceptSnapshot({
-    value: taskPayload,
-    validate: validateTaskCollection,
-    previous: null,
-    policy,
-    source: 'gateway:/api/tasks',
-    now: NOW,
-  });
-  if (result.outcome !== 'accepted') {
-    throw new Error(`fixture setup failed: ${result.reason}`);
-  }
-  return { ...result.snapshot, ...overrides };
-}
-
-describe('computeFreshness', () => {
-  it('treats a missing snapshot as unavailable, never as an empty healthy collection', () => {
-    expect(computeFreshness({ snapshot: null, policy, now: NOW })).toBe('unavailable');
-  });
-
-  it('returns current for a fresh verified snapshot regardless of data emptiness', () => {
-    const empty = acceptSnapshot({
-      value: [],
-      validate: validateTaskCollection,
-      previous: null,
-      policy,
-      source: 'gateway:/api/tasks',
-      now: NOW,
-    });
-    if (empty.outcome !== 'accepted') throw new Error('expected acceptance');
-    expect(computeFreshness({ snapshot: empty.snapshot, policy, now: NOW })).toBe('current');
-  });
-
-  it('degrades to stale once the snapshot ages past staleAfterMs', () => {
-    const snapshot = acceptedTaskSnapshot();
-    expect(computeFreshness({ snapshot, policy, now: NOW + 60_001 })).toBe('stale');
-    expect(computeFreshness({ snapshot, policy, now: NOW + 59_999 })).toBe('current');
-  });
-
-  it('degrades to stale when the latest revalidation failed', () => {
-    const snapshot = acceptedTaskSnapshot();
-    expect(computeFreshness({ snapshot, policy, now: NOW, degraded: true })).toBe('stale');
-  });
-});
-
-describe('mutation guard', () => {
-  it('permits mutations only on current data', () => {
-    expect(canMutate('current')).toBe(true);
-    for (const state of ['stale', 'partial', 'unknown', 'unavailable'] as const) {
-      expect(canMutate(state)).toBe(false);
-    }
-  });
-
-  it('refuses mutations on non-current data via assertMutable', () => {
-    expect(() => assertMutable('current')).not.toThrow();
-    for (const state of ['stale', 'partial', 'unknown', 'unavailable'] as const) {
-      let thrown: unknown;
-      try {
-        assertMutable(state);
-      } catch (caught) {
-        thrown = caught;
-      }
-      expect(thrown).toBeInstanceOf(StaleMutationError);
-      expect(thrown).toBeInstanceOf(Error);
-      if (thrown instanceof StaleMutationError) {
-        expect(thrown.name).toBe('StaleMutationError');
-        expect(thrown.freshness).toBe(state);
-        expect(thrown.message).toContain(state);
-        expect(thrown.message).toContain('revalidat');
-      }
-    }
-  });
-});
-
-describe('acceptSnapshot', () => {
-  it('accepts a valid payload with provenance', () => {
-    const result = acceptSnapshot({
-      value: taskPayload,
-      validate: validateTaskCollection,
-      previous: null,
-      policy,
-      source: 'gateway:/api/tasks',
-      now: NOW,
-    });
-    expect(result.outcome).toBe('accepted');
-    if (result.outcome !== 'accepted') return;
-    expect(result.snapshot.source).toBe('gateway:/api/tasks');
-    expect(result.snapshot.version).toBe(1);
-    expect(result.snapshot.fetchedAt).toBe(NOW);
-    expect(result.snapshot.data).toEqual(taskPayload);
-  });
-
-  it('invalidates a schema-mismatched payload instead of rendering it', () => {
-    const result = acceptSnapshot({
-      value: { not: 'an array' },
-      validate: validateTaskCollection,
-      previous: acceptedTaskSnapshot(),
-      policy,
-      source: 'gateway:/api/tasks',
-      now: NOW,
-    });
-    expect(result).toEqual({ outcome: 'invalidated', reason: 'schema-mismatch' });
-    expect(invalidationReasonLabels['schema-mismatch']).toContain('schema');
-  });
-
-  it('invalidates cross-workspace payloads', () => {
-    const userOne = acceptSnapshot({
-      value: [
-        {
-          id: 'p1',
-          name: 'P1',
-          description: null,
-          status: 'active',
-          userId: 'user-1',
-          metadata: null,
-          createdAt: '2026-08-01T00:00:00.000Z',
-          updatedAt: '2026-08-01T00:00:00.000Z',
-        },
-      ],
-      validate: validateProjectCollection,
-      previous: null,
-      policy,
-      source: 'gateway:/api/projects',
-      now: NOW,
-    });
-    if (userOne.outcome !== 'accepted') throw new Error('expected acceptance');
-
-    const switched = acceptSnapshot({
-      value: [
-        {
-          id: 'p9',
-          name: 'P9',
-          description: null,
-          status: 'active',
-          userId: 'user-2',
-          metadata: null,
-          createdAt: '2026-08-01T00:00:00.000Z',
-          updatedAt: '2026-08-01T00:00:00.000Z',
-        },
-      ],
-      validate: validateProjectCollection,
-      previous: userOne.snapshot,
-      policy,
-      source: 'gateway:/api/projects',
-      now: NOW,
-    });
-    expect(switched).toEqual({ outcome: 'invalidated', reason: 'cross-workspace' });
-  });
-
-  it('keeps the previous workspace for collections with no intrinsic identity', () => {
-    const userOne = acceptSnapshot({
-      value: [
-        {
-          id: 'p1',
-          name: 'P1',
-          description: null,
-          status: 'active',
-          userId: 'user-1',
-          metadata: null,
-          createdAt: '2026-08-01T00:00:00.000Z',
-          updatedAt: '2026-08-01T00:00:00.000Z',
-        },
-      ],
-      validate: validateProjectCollection,
-      previous: null,
-      policy,
-      source: 'gateway:/api/projects',
-      now: NOW,
-    });
-    if (userOne.outcome !== 'accepted') throw new Error('expected acceptance');
-
-    // Empty list after the user deleted every project: no identity to check,
-    // so the verified scope is retained and the empty state stays healthy.
-    const emptied = acceptSnapshot({
-      value: [],
-      validate: validateProjectCollection,
-      previous: userOne.snapshot,
-      policy,
-      source: 'gateway:/api/projects',
-      now: NOW,
-    });
-    expect(emptied.outcome).toBe('accepted');
-    if (emptied.outcome === 'accepted') {
-      expect(emptied.snapshot.data).toEqual([]);
-      expect(emptied.snapshot.workspace).toBe('user-1');
-    }
-  });
-
-  it('invalidates version regressions', () => {
-    const previous = acceptedTaskSnapshot({ version: 7 });
-    const regressed = acceptSnapshot({
-      value: taskPayload,
-      validate: validateTaskCollection,
-      previous,
-      policy,
-      source: 'gateway:/api/tasks',
-      now: NOW,
-      incomingVersion: 3,
-    });
-    expect(regressed).toEqual({ outcome: 'invalidated', reason: 'version-regression' });
-
-    const newerSchema = acceptedTaskSnapshot({ schemaVersion: 4 });
-    const downgradedClient = acceptSnapshot({
-      value: taskPayload,
-      validate: validateTaskCollection,
-      previous: newerSchema,
-      policy: { ...policy, schemaVersion: 2 },
-      source: 'gateway:/api/tasks',
-      now: NOW,
-    });
-    expect(downgradedClient).toEqual({ outcome: 'invalidated', reason: 'version-regression' });
-  });
-
-  it('increments the version monotonically across accepted snapshots', () => {
-    const first = acceptedTaskSnapshot();
-    const second = acceptSnapshot({
-      value: taskPayload,
-      validate: validateTaskCollection,
-      previous: first,
-      policy,
-      source: 'gateway:/api/tasks',
-      now: NOW,
-    });
-    expect(second.outcome).toBe('accepted');
-    if (second.outcome === 'accepted') {
-      expect(second.snapshot.version).toBe(first.version + 1);
-    }
-  });
-});
-
-describe('combineFreshness', () => {
-  it('gates the surface on the primary collection', () => {
-    expect(combineFreshness('unavailable', ['current'])).toBe('unavailable');
-    expect(combineFreshness('unknown', ['current'])).toBe('unknown');
-    expect(combineFreshness('current', [])).toBe('current');
-  });
-
-  it('degrades to partial when a secondary is unavailable', () => {
-    expect(combineFreshness('current', ['current', 'unavailable'])).toBe('partial');
-  });
-
-  it('degrades to unknown while a secondary is still loading', () => {
-    expect(combineFreshness('current', ['unknown'])).toBe('unknown');
-  });
-
-  it('degrades to stale when any collection is stale', () => {
-    expect(combineFreshness('current', ['stale'])).toBe('stale');
-    expect(combineFreshness('stale', ['current'])).toBe('stale');
-  });
-
-  it('propagates partial secondaries', () => {
-    expect(combineFreshness('current', ['partial'])).toBe('partial');
-  });
-});
-
-describe('computeDigest', () => {
-  it('is stable across key order and changes with data', () => {
-    const a = computeDigest({ x: 1, y: [1, 2] });
-    const b = computeDigest({ y: [1, 2], x: 1 });
-    expect(a).toBe(b);
-    expect(computeDigest({ x: 1, y: [1, 3] })).not.toBe(a);
-  });
-});
-
-describe('verdictValue', () => {
-  it('returns the value only for verified inputs', () => {
-    expect(verdictValue(true, '5')).toBe('5');
-    expect(verdictValue(false, '5')).toBe(UNKNOWN_VERDICT);
-    expect(verdictValue(false, '5')).not.toBe('5');
-  });
-});
-
-describe('formatAge', () => {
-  it('labels age in human terms', () => {
-    expect(formatAge(NOW, NOW)).toBe('just now');
-    expect(formatAge(NOW, NOW + 15_000)).toBe('under a minute ago');
-    expect(formatAge(NOW, NOW + 120_000)).toBe('2m ago');
-    expect(formatAge(NOW, NOW + 3 * 3_600_000)).toBe('3h ago');
-    expect(formatAge(NOW, NOW + 2 * 86_400_000)).toBe('2d ago');
-  });
-});

apps/web/src/lib/freshness/model.ts

@@ -1,261 +0,0 @@
-/**
- * Typed freshness model for gateway-fetched collections (RI-5-001).
- *
- * A failed or stale fetch must never be indistinguishable from an empty
- * healthy collection. Every fetched surface carries an explicit freshness
- * state, a verified snapshot identity (source, workspace, version, age), and
- * a mutation guard that refuses state-changing operations unless the data is
- * verified current.
- */
-
-/** Freshness states for fetched data. Never inferred from emptiness. */
-export type FreshnessState = 'current' | 'stale' | 'partial' | 'unknown' | 'unavailable';
-
-/**
- * Reasons a snapshot is invalidated. An invalidated snapshot is treated as
- * unavailable and is never rendered as current.
- */
-export type InvalidationReason =
-  | 'cache-corruption'
-  | 'cross-workspace'
-  | 'schema-mismatch'
-  | 'version-regression';
-
-/** Human-readable labels for invalidation reasons (UI + error messages). */
-export const invalidationReasonLabels: Record<InvalidationReason, string> = {
-  'cache-corruption': 'cached snapshot failed integrity checks',
-  'cross-workspace': 'data belongs to a different workspace',
-  'schema-mismatch': 'response did not match the expected schema',
-  'version-regression': 'snapshot version regressed below the accepted version',
-};
-
-/** A verified snapshot of fetched data with full provenance. */
-export interface FreshSnapshot<T> {
-  readonly data: T;
-  /** Source identity of the fetch, e.g. `gateway:/api/tasks`. */
-  readonly source: string;
-  /** Workspace scope the data belongs to. */
-  readonly workspace: string;
-  /** Monotonic snapshot sequence number for this surface. */
-  readonly version: number;
-  /** Schema version of the validator that accepted this snapshot. */
-  readonly schemaVersion: number;
-  /** Epoch ms at which the data was verified. */
-  readonly fetchedAt: number;
-  /** Integrity digest of `data`, used to detect cache corruption. */
-  readonly digest: string;
-}
-
-/** Provenance label rendered next to last-known data. */
-export interface FreshnessLabel {
-  readonly source: string;
-  readonly version: number;
-  readonly fetchedAt: number;
-}
-
-/** Policy governing freshness for a surface. */
-export interface FreshnessPolicy {
-  /** Active workspace scope. Snapshots from other scopes are invalidated. */
-  readonly workspace: string;
-  /** Schema version of the current validator. */
-  readonly schemaVersion: number;
-  /** Age after which a verified snapshot degrades from current to stale. */
-  readonly staleAfterMs: number;
-}
-
-export const DEFAULT_FRESHNESS_POLICY: FreshnessPolicy = {
-  workspace: 'default',
-  schemaVersion: 1,
-  staleAfterMs: 60_000,
-};
-
-/** Payload returned by a successful schema validation. */
-export interface FreshPayload<T> {
-  readonly data: T;
-  /**
-   * Workspace identity extracted from the payload itself when the collection
-   * carries one (e.g. a uniform `userId` on projects). `null` when the
-   * collection has no intrinsic workspace identity.
-   */
-  readonly workspace: string | null;
-}
-
-/** Error thrown when a mutation is attempted on non-current data. */
-export class StaleMutationError extends Error {
-  readonly freshness: FreshnessState;
-
-  constructor(freshness: FreshnessState) {
-    super(`Refused mutation on ${freshness} data: revalidation is required before mutating.`);
-    this.name = 'StaleMutationError';
-    this.freshness = freshness;
-  }
-}
-
-/** Stable JSON digest used for snapshot integrity checks. */
-export function computeDigest(value: unknown): string {
-  // FNV-1a 32-bit over the stable JSON serialization. This is an integrity
-  // check against corruption, not a cryptographic guarantee.
-  let hash = 0x811c9dc5;
-  for (const byte of stableStringify(value)) {
-    hash ^= byte.charCodeAt(0);
-    hash = Math.imul(hash, 0x01000193) >>> 0;
-  }
-  return hash.toString(16).padStart(8, '0');
-}
-
-function stableStringify(value: unknown): string {
-  return serialize(value);
-}
-
-function serialize(value: unknown): string {
-  if (value === null || typeof value !== 'object') return JSON.stringify(value) ?? 'null';
-  if (Array.isArray(value)) return `[${value.map(serialize).join(',')}]`;
-  const entries = Object.entries(value as Record<string, unknown>)
-    .filter(([, item]) => item !== undefined)
-    .sort(([left], [right]) => (left < right ? -1 : left > right ? 1 : 0))
-    .map(([key, item]) => `${JSON.stringify(key)}:${serialize(item)}`);
-  return `{${entries.join(',')}}`;
-}
-
-export type AcceptSnapshotResult<T> =
-  | { readonly outcome: 'accepted'; readonly snapshot: FreshSnapshot<T> }
-  | { readonly outcome: 'invalidated'; readonly reason: InvalidationReason };
-
-export interface AcceptSnapshotOptions<T> {
-  /** Raw fetched value (untrusted JSON). */
-  readonly value: unknown;
-  /** Schema validator; returns `null` when the value does not match. */
-  readonly validate: (value: unknown) => FreshPayload<T> | null;
-  /** Previously accepted snapshot for this surface, if any. */
-  readonly previous: FreshSnapshot<T> | null;
-  readonly policy: FreshnessPolicy;
-  readonly source: string;
-  /**
-   * Version carried by the incoming payload when the transport exposes one.
-   * Must not regress below the accepted snapshot's version.
-   */
-  readonly incomingVersion?: number;
-  readonly now: number;
-}
-
-/**
- * Validate and accept a fetched value as a snapshot, or invalidate it.
- *
- * Invalidation rules (each treated as unavailable, never rendered current):
- * - schema mismatch: the payload fails validation
- * - cross-workspace: the payload's workspace differs from the verified one
- * - version regression: payload/schema version is below the accepted one
- */
-export function acceptSnapshot<T>(options: AcceptSnapshotOptions<T>): AcceptSnapshotResult<T> {
-  const payload = options.validate(options.value);
-  if (payload === null) {
-    return { outcome: 'invalidated', reason: 'schema-mismatch' };
-  }
-
-  // Workspace identity: the payload's own scope wins; a collection with no
-  // intrinsic identity (e.g. an empty list after every project was deleted)
-  // keeps the previously verified scope rather than resetting to the policy
-  // default, so a legitimately empty response is not mistaken for a scope
-  // change.
-  const workspace = payload.workspace ?? options.previous?.workspace ?? options.policy.workspace;
-  if (options.previous !== null && options.previous.workspace !== workspace) {
-    return { outcome: 'invalidated', reason: 'cross-workspace' };
-  }
-  if (options.previous !== null && options.policy.schemaVersion < options.previous.schemaVersion) {
-    return { outcome: 'invalidated', reason: 'version-regression' };
-  }
-  if (
-    options.incomingVersion !== undefined &&
-    options.previous !== null &&
-    options.incomingVersion < options.previous.version
-  ) {
-    return { outcome: 'invalidated', reason: 'version-regression' };
-  }
-
-  const snapshot: FreshSnapshot<T> = {
-    data: payload.data,
-    source: options.source,
-    workspace,
-    version: options.incomingVersion ?? (options.previous?.version ?? 0) + 1,
-    schemaVersion: options.policy.schemaVersion,
-    fetchedAt: options.now,
-    digest: computeDigest(payload.data),
-  };
-  return { outcome: 'accepted', snapshot };
-}
-
-export interface ComputeFreshnessOptions {
-  readonly snapshot: FreshSnapshot<unknown> | null;
-  readonly policy: FreshnessPolicy;
-  readonly now: number;
-  /**
-   * True when the snapshot cannot be trusted as current regardless of age:
-   * the latest revalidation failed, or the snapshot was restored from cache
-   * and has not been verified by a fetch in this session.
-   */
-  readonly degraded?: boolean;
-}
-
-/**
- * Compute the freshness state of a snapshot. A missing snapshot is
- * `unavailable` (never "empty and healthy"); a degraded or aged snapshot is
- * `stale` (situational awareness only).
- */
-export function computeFreshness(options: ComputeFreshnessOptions): FreshnessState {
-  const { snapshot, policy, now, degraded = false } = options;
-  if (snapshot === null) return 'unavailable';
-  if (degraded) return 'stale';
-  if (now - snapshot.fetchedAt > policy.staleAfterMs) return 'stale';
-  return 'current';
-}
-
-/** Only verified-current data may back a state-changing action. */
-export function canMutate(state: FreshnessState): boolean {
-  return state === 'current';
-}
-
-/** Defense in depth: reject the mutation call itself on non-current data. */
-export function assertMutable(state: FreshnessState): void {
-  if (!canMutate(state)) {
-    throw new StaleMutationError(state);
-  }
-}
-
-/**
- * Combine freshness across a multi-collection surface (primary + secondaries).
- * The primary collection gates the surface: unknown while it loads,
- * unavailable when it fails. Missing secondaries degrade the surface to
- * `partial`; aged collections degrade it to `stale`.
- */
-export function combineFreshness(
-  primary: FreshnessState,
-  secondaries: readonly FreshnessState[],
-): FreshnessState {
-  if (primary === 'unavailable') return 'unavailable';
-  if (primary === 'unknown') return 'unknown';
-  if (secondaries.includes('unavailable')) return 'partial';
-  if (secondaries.includes('unknown')) return 'unknown';
-  if (secondaries.includes('stale') || primary === 'stale') return 'stale';
-  if (secondaries.includes('partial')) return 'partial';
-  return 'current';
-}
-
-/** Render-safe age label for snapshot provenance. */
-export function formatAge(fetchedAt: number, now: number): string {
-  const ageMs = Math.max(0, now - fetchedAt);
-  if (ageMs < 10_000) return 'just now';
-  const minutes = Math.floor(ageMs / 60_000);
-  if (minutes < 1) return 'under a minute ago';
-  if (minutes < 60) return `${minutes}m ago`;
-  const hours = Math.floor(minutes / 60);
-  if (hours < 24) return `${hours}h ago`;
-  const days = Math.floor(hours / 24);
-  return `${days}d ago`;
-}
-
-/** Derived verdict placeholder for non-current inputs — never a green value. */
-export const UNKNOWN_VERDICT = '?';
-
-export function verdictValue(verified: boolean, value: string): string {
-  return verified ? value : UNKNOWN_VERDICT;
-}

apps/web/src/lib/freshness/snapshot-cache.spec.ts

@@ -1,197 +0,0 @@
-import { afterEach, beforeEach, describe, expect, it } from 'vitest';
-import { acceptSnapshot, DEFAULT_FRESHNESS_POLICY } from './model';
-import { clearSnapshotCache, readSnapshotCache, writeSnapshotCache } from './snapshot-cache';
-import { validateProjectCollection, validateTaskCollection } from './validators';
-import { projectFixtures, taskFixtures } from '@/spa/pages/page-fixtures';
-import type { Project, Task } from '@/lib/types';
-
-const KEY = 'test:tasks';
-const NOW = 1_800_000_000_000;
-const policy = { ...DEFAULT_FRESHNESS_POLICY, staleAfterMs: 60_000 };
-
-function storedTaskSnapshot() {
-  const result = acceptSnapshot({
-    value: taskFixtures,
-    validate: validateTaskCollection,
-    previous: null,
-    policy,
-    source: 'gateway:/api/tasks',
-    now: NOW,
-  });
-  if (result.outcome !== 'accepted') throw new Error('fixture setup failed');
-  return result.snapshot;
-}
-
-function storedProjectSnapshot() {
-  const result = acceptSnapshot({
-    value: projectFixtures,
-    validate: validateProjectCollection,
-    previous: null,
-    policy,
-    source: 'gateway:/api/projects',
-    now: NOW,
-  });
-  if (result.outcome !== 'accepted') throw new Error('fixture setup failed');
-  return result.snapshot;
-}
-
-function readTasks() {
-  return readSnapshotCache({
-    key: KEY,
-    workspace: policy.workspace,
-    policy,
-    validate: validateTaskCollection,
-  });
-}
-
-/** Write an arbitrary value directly at the raw cache slot. */
-function writeRaw(key: string, value: unknown): void {
-  sessionStorage.setItem(`mosaic:freshness:v1:${key}`, JSON.stringify(value));
-}
-
-/** Parse and re-write the stored entry (for tampering with internals). */
-function tamperStored<T>(key: string, mutate: (stored: T) => void): void {
-  const parsed = JSON.parse(sessionStorage.getItem(`mosaic:freshness:v1:${key}`) ?? '{}') as T;
-  mutate(parsed);
-  writeRaw(key, parsed);
-}
-
-beforeEach(() => {
-  sessionStorage.clear();
-});
-
-afterEach(() => {
-  sessionStorage.clear();
-});
-
-describe('readSnapshotCache', () => {
-  it('misses when nothing is stored', () => {
-    expect(readTasks()).toEqual({ outcome: 'miss' });
-  });
-
-  it('hits for a well-formed entry and preserves provenance', () => {
-    const snapshot = storedTaskSnapshot();
-    writeSnapshotCache(KEY, snapshot);
-
-    const result = readTasks();
-    expect(result.outcome).toBe('hit');
-    if (result.outcome === 'hit') {
-      expect(result.snapshot.data).toEqual(taskFixtures);
-      expect(result.snapshot.source).toBe('gateway:/api/tasks');
-      expect(result.snapshot.version).toBe(snapshot.version);
-      expect(result.snapshot.fetchedAt).toBe(snapshot.fetchedAt);
-      expect(result.snapshot.workspace).toBe(snapshot.workspace);
-    }
-  });
-
-  it('invalidates unparsable entries as cache corruption', () => {
-    sessionStorage.setItem(`mosaic:freshness:v1:${KEY}`, '{not json');
-    expect(readTasks()).toEqual({ outcome: 'invalidated', reason: 'cache-corruption' });
-  });
-
-  it('invalidates structurally wrong entries as cache corruption', () => {
-    const malformed: unknown[] = [
-      'nested but not a snapshot',
-      { data: taskFixtures }, // missing provenance fields
-      {
-        data: taskFixtures,
-        source: 1,
-        workspace: 'w',
-        version: 1,
-        schemaVersion: 1,
-        fetchedAt: 1,
-        digest: 'x',
-      },
-      null,
-      17,
-    ];
-    for (const entry of malformed) {
-      writeRaw(KEY, entry);
-      expect(readTasks()).toEqual({ outcome: 'invalidated', reason: 'cache-corruption' });
-    }
-  });
-
-  it('invalidates digest mismatches as cache corruption (tampered data)', () => {
-    writeSnapshotCache(KEY, storedTaskSnapshot());
-    tamperStored<{ data: Task[] }>(KEY, (stored) => {
-      stored.data = [...stored.data, { ...stored.data[0]!, id: 'injected-task' }];
-    });
-    expect(readTasks()).toEqual({ outcome: 'invalidated', reason: 'cache-corruption' });
-  });
-
-  it('invalidates entries scoped to another workspace', () => {
-    const snapshot = storedTaskSnapshot();
-    writeSnapshotCache(KEY, { ...snapshot, workspace: 'someone-else' });
-    expect(readTasks()).toEqual({ outcome: 'invalidated', reason: 'cross-workspace' });
-  });
-
-  it('invalidates entries written by a newer schema as a version regression', () => {
-    const snapshot = storedTaskSnapshot();
-    writeSnapshotCache(KEY, { ...snapshot, schemaVersion: policy.schemaVersion + 1 });
-    expect(readTasks()).toEqual({ outcome: 'invalidated', reason: 'version-regression' });
-  });
-
-  it('invalidates entries whose data no longer validates (schema mismatch)', () => {
-    writeSnapshotCache(KEY, storedTaskSnapshot());
-    tamperStored<{ data: unknown }>(KEY, (stored) => {
-      stored.data = { malformed: true };
-    });
-    expect(readTasks()).toEqual({ outcome: 'invalidated', reason: 'schema-mismatch' });
-  });
-
-  it('never reports a corrupted raw entry as a hit (negative control)', () => {
-    for (const raw of ['{oops', 'null', '"string"', '[]', '12']) {
-      sessionStorage.setItem(`mosaic:freshness:v1:${KEY}`, raw);
-      const result = readTasks();
-      expect(result.outcome).not.toBe('hit');
-      expect(result.outcome).toBe('invalidated');
-    }
-  });
-
-  it('scopes project collections by their workspace identity', () => {
-    const snapshot = storedProjectSnapshot();
-    writeSnapshotCache('test:projects', snapshot);
-
-    const sameScope = readSnapshotCache({
-      key: 'test:projects',
-      workspace: 'user-1',
-      policy,
-      validate: validateProjectCollection,
-    });
-    expect(sameScope.outcome).toBe('hit');
-
-    const foreignScope = readSnapshotCache({
-      key: 'test:projects',
-      workspace: 'user-2',
-      policy,
-      validate: validateProjectCollection,
-    });
-    expect(foreignScope).toEqual({ outcome: 'invalidated', reason: 'cross-workspace' });
-  });
-});
-
-describe('writeSnapshotCache round-trip', () => {
-  it('round-trips an accepted project snapshot', () => {
-    const snapshot = storedProjectSnapshot();
-    writeSnapshotCache('test:projects', snapshot);
-    const result = readSnapshotCache({
-      key: 'test:projects',
-      workspace: snapshot.workspace,
-      policy,
-      validate: validateProjectCollection,
-    });
-    expect(result.outcome).toBe('hit');
-    if (result.outcome === 'hit') {
-      expect(result.snapshot.data).toEqual(projectFixtures as Project[]);
-    }
-  });
-});
-
-describe('clearSnapshotCache', () => {
-  it('drops the entry so the next read misses', () => {
-    writeSnapshotCache(KEY, storedTaskSnapshot());
-    expect(readTasks().outcome).toBe('hit');
-    clearSnapshotCache(KEY);
-    expect(readTasks()).toEqual({ outcome: 'miss' });
-  });
-});

apps/web/src/lib/freshness/snapshot-cache.ts

@@ -1,154 +0,0 @@
-import {
-  computeDigest,
-  type FreshPayload,
-  type FreshSnapshot,
-  type FreshnessPolicy,
-  type InvalidationReason,
-} from './model';
-
-/**
- * Session-scoped last-known snapshot cache (RI-5-001).
- *
- * Restored snapshots are situational awareness only: they surface as `stale`
- * until a fetch re-verifies them. A cache entry that is corrupted, belongs to
- * another workspace, was written by a newer schema, or no longer validates is
- * invalidated (treated as unavailable, never rendered as current).
- */
-
-const CACHE_PREFIX = 'mosaic:freshness:v1';
-
-interface StoredSnapshot {
-  data: unknown;
-  source: string;
-  workspace: string;
-  version: number;
-  schemaVersion: number;
-  fetchedAt: number;
-  digest: string;
-}
-
-export type SnapshotCacheRead<T> =
-  | { readonly outcome: 'hit'; readonly snapshot: FreshSnapshot<T> }
-  | { readonly outcome: 'miss' }
-  | { readonly outcome: 'invalidated'; readonly reason: InvalidationReason };
-
-export interface ReadSnapshotCacheOptions<T> {
-  readonly key: string;
-  readonly workspace: string;
-  readonly policy: FreshnessPolicy;
-  readonly validate: (value: unknown) => FreshPayload<T> | null;
-}
-
-function cacheKey(key: string): string {
-  return `${CACHE_PREFIX}:${key}`;
-}
-
-function isStoredSnapshot(value: unknown): value is StoredSnapshot {
-  if (typeof value !== 'object' || value === null) return false;
-  const candidate = value as Record<string, unknown>;
-  return (
-    typeof candidate['data'] === 'object' &&
-    candidate['data'] !== null &&
-    typeof candidate['source'] === 'string' &&
-    typeof candidate['workspace'] === 'string' &&
-    typeof candidate['version'] === 'number' &&
-    typeof candidate['schemaVersion'] === 'number' &&
-    typeof candidate['fetchedAt'] === 'number' &&
-    typeof candidate['digest'] === 'string'
-  );
-}
-
-function getStorage(): Storage | null {
-  try {
-    return globalThis.sessionStorage ?? null;
-  } catch {
-    return null;
-  }
-}
-
-/**
- * Restore a cached snapshot under the active workspace scope. Every failure
- * mode maps to an explicit invalidation reason or a miss — never to data
- * that renders as current.
- */
-export function readSnapshotCache<T>(options: ReadSnapshotCacheOptions<T>): SnapshotCacheRead<T> {
-  const storage = getStorage();
-  if (storage === null) return { outcome: 'miss' };
-
-  let raw: string | null;
-  try {
-    raw = storage.getItem(cacheKey(options.key));
-  } catch {
-    return { outcome: 'miss' };
-  }
-  if (raw === null) return { outcome: 'miss' };
-
-  let parsed: unknown;
-  try {
-    parsed = JSON.parse(raw);
-  } catch {
-    return { outcome: 'invalidated', reason: 'cache-corruption' };
-  }
-  if (!isStoredSnapshot(parsed)) {
-    return { outcome: 'invalidated', reason: 'cache-corruption' };
-  }
-  if (parsed.workspace !== options.workspace) {
-    return { outcome: 'invalidated', reason: 'cross-workspace' };
-  }
-  if (parsed.schemaVersion > options.policy.schemaVersion) {
-    // Written by a newer build than the running client: version regression.
-    return { outcome: 'invalidated', reason: 'version-regression' };
-  }
-
-  const payload = options.validate(parsed.data);
-  if (payload === null) {
-    return { outcome: 'invalidated', reason: 'schema-mismatch' };
-  }
-  if (computeDigest(payload.data) !== parsed.digest) {
-    return { outcome: 'invalidated', reason: 'cache-corruption' };
-  }
-
-  return {
-    outcome: 'hit',
-    snapshot: {
-      data: payload.data,
-      source: parsed.source,
-      workspace: parsed.workspace,
-      version: parsed.version,
-      schemaVersion: parsed.schemaVersion,
-      fetchedAt: parsed.fetchedAt,
-      digest: parsed.digest,
-    },
-  };
-}
-
-/** Persist a verified snapshot. Failures are non-fatal (cache is best-effort). */
-export function writeSnapshotCache<T>(key: string, snapshot: FreshSnapshot<T>): void {
-  const storage = getStorage();
-  if (storage === null) return;
-  const stored: StoredSnapshot = {
-    data: snapshot.data,
-    source: snapshot.source,
-    workspace: snapshot.workspace,
-    version: snapshot.version,
-    schemaVersion: snapshot.schemaVersion,
-    fetchedAt: snapshot.fetchedAt,
-    digest: snapshot.digest,
-  };
-  try {
-    storage.setItem(cacheKey(key), JSON.stringify(stored));
-  } catch {
-    // Quota or serialization failures simply skip caching.
-  }
-}
-
-/** Drop a cached snapshot (used when a surface invalidates its cache entry). */
-export function clearSnapshotCache(key: string): void {
-  const storage = getStorage();
-  if (storage === null) return;
-  try {
-    storage.removeItem(cacheKey(key));
-  } catch {
-    // Ignorable: a wedged storage entry is detected as corruption on read.
-  }
-}

apps/web/src/lib/freshness/use-fresh-collection.spec.tsx

@@ -1,372 +0,0 @@
-import { act } from 'react';
-import { createRoot, type Root } from 'react-dom/client';
-import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from 'vitest';
-import type { Task } from '@/lib/types';
-import { acceptSnapshot, StaleMutationError, DEFAULT_FRESHNESS_POLICY } from './model';
-import type { FreshnessFailure } from './use-fresh-collection';
-import {
-  describeFailure,
-  useFreshCollection,
-  type FreshCollection,
-  type UseFreshCollectionOptions,
-} from './use-fresh-collection';
-import { validateProjectCollection, validateTaskCollection } from './validators';
-import { projectFixtures, taskFixtures } from '@/spa/pages/page-fixtures';
-
-/**
- * Failure-matrix coverage for the freshness seam (RI-5-001): network failure,
- * auth failure, malformed response, cache corruption, stale age, schema
- * mismatch, cross-workspace, recovery, and stale-action rejection — with
- * negative controls proving no case yields current data or an enabled
- * mutation.
- */
-
-const NOW = 1_800_000_000_000;
-
-interface Deferred<T> {
-  promise: Promise<T>;
-  resolve: (value: T) => void;
-  reject: (reason?: unknown) => void;
-}
-
-function createDeferred<T>(): Deferred<T> {
-  let resolve!: (value: T) => void;
-  let reject!: (reason?: unknown) => void;
-  const promise = new Promise<T>((res, rej) => {
-    resolve = res;
-    reject = rej;
-  });
-  return { promise, resolve, reject };
-}
-
-let root: Root | null = null;
-let container: HTMLDivElement;
-let latest: FreshCollection<Task[]> | null = null;
-
-function Probe({
-  options,
-}: {
-  options: UseFreshCollectionOptions<Task[]>;
-}): React.ReactElement | null {
-  latest = useFreshCollection<Task[]>(options);
-  return null;
-}
-
-beforeAll(() => {
-  Object.defineProperty(globalThis, 'IS_REACT_ACT_ENVIRONMENT', {
-    configurable: true,
-    value: true,
-  });
-});
-
-beforeEach(() => {
-  sessionStorage.clear();
-});
-
-afterEach(async () => {
-  await act(async () => {
-    root?.unmount();
-  });
-  document.body.replaceChildren();
-  root = null;
-  latest = null;
-  sessionStorage.clear();
-  vi.restoreAllMocks();
-});
-
-async function renderCollection(
-  options: UseFreshCollectionOptions<Task[]>,
-): Promise<FreshCollection<Task[]>> {
-  container = document.createElement('div');
-  document.body.append(container);
-  root = createRoot(container);
-  await act(async () => {
-    root?.render(<Probe options={options} />);
-  });
-  if (latest === null) throw new Error('hook did not run');
-  return latest;
-}
-
-function taskOptions(
-  overrides: Partial<UseFreshCollectionOptions<Task[]>> = {},
-): UseFreshCollectionOptions<Task[]> {
-  return {
-    source: 'gateway:/api/tasks',
-    fetcher: () => Promise.resolve(taskFixtures),
-    validate: validateTaskCollection,
-    cacheKey: 'tasks',
-    clock: () => NOW,
-    ...overrides,
-  };
-}
-
-function authError(statusCode: number): Error & { statusCode: number } {
-  return Object.assign(new Error(`Request failed with ${statusCode}`), { statusCode });
-}
-
-function seedCache(key: string): number {
-  const result = acceptSnapshot({
-    value: taskFixtures,
-    validate: validateTaskCollection,
-    previous: null,
-    policy: DEFAULT_FRESHNESS_POLICY,
-    source: 'gateway:/api/tasks',
-    now: NOW,
-  });
-  if (result.outcome !== 'accepted') throw new Error('fixture setup failed');
-  sessionStorage.setItem(`mosaic:freshness:v1:${key}`, JSON.stringify({ ...result.snapshot }));
-  return result.snapshot.version;
-}
-
-describe('useFreshCollection failure matrix', () => {
-  it('is unknown (not empty) while the first validation is in flight', async () => {
-    const deferred = createDeferred<Task[]>();
-    const collection = await renderCollection(taskOptions({ fetcher: () => deferred.promise }));
-
-    expect(collection.freshness).toBe('unknown');
-    expect(collection.validating).toBe(true);
-    expect(collection.data).toBeNull();
-    expect(collection.canMutate).toBe(false);
-
-    await act(async () => {
-      deferred.resolve(taskFixtures);
-      await deferred.promise;
-    });
-  });
-
-  it('becomes current with provenance after a verified fetch', async () => {
-    const collection = await renderCollection(taskOptions());
-
-    expect(collection.freshness).toBe('current');
-    expect(collection.data).toEqual(taskFixtures);
-    expect(collection.snapshot?.source).toBe('gateway:/api/tasks');
-    expect(collection.snapshot?.version).toBe(1);
-    expect(collection.failure).toBeNull();
-    expect(collection.canMutate).toBe(true);
-    // Verified snapshot is persisted for last-known restore.
-    expect(sessionStorage.getItem('mosaic:freshness:v1:tasks')).toBeTruthy();
-  });
-
-  it('treats a network failure as unavailable — never an empty healthy collection', async () => {
-    const collection = await renderCollection(
-      taskOptions({ fetcher: () => Promise.reject(new Error('network down')) }),
-    );
-
-    expect(collection.freshness).toBe('unavailable');
-    expect(collection.data).toBeNull();
-    expect(collection.failure).toEqual({ kind: 'fetch', message: 'network down' });
-    expect(collection.canMutate).toBe(false);
-    expect(describeFailure(collection.failure)).toBe('network down');
-  });
-
-  it('treats an auth failure as unavailable and drops the last-known snapshot', async () => {
-    let call = 0;
-    const collection = await renderCollection(
-      taskOptions({
-        fetcher: () => {
-          call += 1;
-          return call === 1 ? Promise.resolve(taskFixtures) : Promise.reject(authError(401));
-        },
-      }),
-    );
-    expect(collection.freshness).toBe('current');
-
-    await act(async () => {
-      await collection.revalidate();
-    });
-
-    expect(latest?.freshness).toBe('unavailable');
-    expect(latest?.data).toBeNull();
-    expect(latest?.failure?.kind).toBe('fetch');
-    // The previous user's data must not linger in the session cache.
-    expect(sessionStorage.getItem('mosaic:freshness:v1:tasks')).toBeNull();
-  });
-
-  it('invalidates a malformed response as a schema mismatch', async () => {
-    const collection = await renderCollection(
-      taskOptions({ fetcher: () => Promise.resolve({ malformed: true }) }),
-    );
-
-    expect(collection.freshness).toBe('unavailable');
-    expect(collection.data).toBeNull();
-    expect(collection.failure).toEqual({ kind: 'invalidated', reason: 'schema-mismatch' });
-    expect(collection.canMutate).toBe(false);
-  });
-
-  it('keeps the previous snapshot as labeled stale when a later payload mismatches', async () => {
-    let call = 0;
-    const collection = await renderCollection(
-      taskOptions({
-        fetcher: () => {
-          call += 1;
-          return call === 1 ? Promise.resolve(taskFixtures) : Promise.resolve('garbage');
-        },
-      }),
-    );
-    expect(collection.freshness).toBe('current');
-
-    await act(async () => {
-      await collection.revalidate();
-    });
-
-    expect(latest?.freshness).toBe('stale');
-    expect(latest?.data).toEqual(taskFixtures);
-    expect(latest?.failure).toEqual({ kind: 'invalidated', reason: 'schema-mismatch' });
-    expect(latest?.canMutate).toBe(false);
-  });
-
-  it('drops the snapshot when the workspace changes under it (cross-workspace)', async () => {
-    let call = 0;
-    const collection = await renderCollection(
-      taskOptions({
-        fetcher: () => {
-          call += 1;
-          return Promise.resolve(
-            call === 1 ? projectFixtures : [{ ...projectFixtures[0], userId: 'user-2' }],
-          );
-        },
-        validate: validateProjectCollection as unknown as (value: unknown) => {
-          data: Task[];
-          workspace: string | null;
-        },
-        source: 'gateway:/api/projects',
-      }),
-    );
-    expect(collection.freshness).toBe('current');
-
-    await act(async () => {
-      await collection.revalidate();
-    });
-
-    expect(latest?.freshness).toBe('unavailable');
-    expect(latest?.data).toBeNull();
-    expect(latest?.failure).toEqual({ kind: 'invalidated', reason: 'cross-workspace' });
-  });
-
-  it('ages from current to stale and refuses mutations on stale data', async () => {
-    let fakeNow = NOW;
-    const collection = await renderCollection(
-      taskOptions({
-        clock: () => fakeNow,
-        policy: { staleAfterMs: 40 },
-        tickMs: 10,
-      }),
-    );
-    expect(collection.freshness).toBe('current');
-
-    // Age the snapshot past the policy and let the tick recompute.
-    fakeNow = NOW + 60;
-    await act(async () => {
-      await new Promise((resolve) => setTimeout(resolve, 25));
-    });
-
-    expect(latest?.freshness).toBe('stale');
-    expect(latest?.data).toEqual(taskFixtures);
-    expect(latest?.canMutate).toBe(false);
-
-    const operation = vi.fn(async () => 'result');
-    await expect(latest?.mutate(operation)).rejects.toBeInstanceOf(StaleMutationError);
-    expect(operation).not.toHaveBeenCalled();
-  });
-
-  it('recovers to current after a successful revalidation', async () => {
-    let call = 0;
-    const collection = await renderCollection(
-      taskOptions({
-        fetcher: () => {
-          call += 1;
-          return call === 1
-            ? Promise.reject(new Error('first attempt failed'))
-            : Promise.resolve(taskFixtures);
-        },
-      }),
-    );
-    expect(collection.freshness).toBe('unavailable');
-
-    await act(async () => {
-      await collection.revalidate();
-    });
-
-    expect(latest?.freshness).toBe('current');
-    expect(latest?.failure).toBeNull();
-
-    const operation = vi.fn(async (data: Task[]) => data.length);
-    await expect(latest?.mutate(operation)).resolves.toBe(taskFixtures.length);
-    expect(operation).toHaveBeenCalledOnce();
-  });
-
-  it('restores a cached snapshot as unverified stale data, then verifies it', async () => {
-    const seededVersion = seedCache('tasks');
-    const deferred = createDeferred<Task[]>();
-    const collection = await renderCollection(taskOptions({ fetcher: () => deferred.promise }));
-
-    // Restored data is situational awareness only: labeled stale, never
-    // current, and mutations are refused before verification.
-    expect(collection.freshness).toBe('stale');
-    expect(collection.data).toEqual(taskFixtures);
-    expect(collection.canMutate).toBe(false);
-    await expect(collection.mutate(vi.fn())).rejects.toBeInstanceOf(StaleMutationError);
-
-    await act(async () => {
-      deferred.resolve(taskFixtures);
-      await deferred.promise;
-    });
-
-    expect(latest?.freshness).toBe('current');
-    expect(latest?.snapshot?.version).toBe(seededVersion + 1);
-  });
-
-  it('never promotes corrupted cache data to current (cache corruption)', async () => {
-    sessionStorage.setItem('mosaic:freshness:v1:tasks', '{"data":');
-    const collection = await renderCollection(
-      taskOptions({ fetcher: () => Promise.reject(new Error('still down')) }),
-    );
-
-    expect(collection.freshness).toBe('unavailable');
-    expect(collection.data).toBeNull();
-    expect(collection.canMutate).toBe(false);
-    // The corrupted entry is dropped so it cannot come back.
-    expect(sessionStorage.getItem('mosaic:freshness:v1:tasks')).toBeNull();
-  });
-
-  it('refuses mutations while unknown or unavailable — the call itself, not just the button', async () => {
-    const deferred = createDeferred<Task[]>();
-    const unknown = await renderCollection(taskOptions({ fetcher: () => deferred.promise }));
-    const operation = vi.fn(async () => 'result');
-    await expect(unknown.mutate(operation)).rejects.toBeInstanceOf(StaleMutationError);
-    expect(operation).not.toHaveBeenCalled();
-    await act(async () => {
-      deferred.reject(new Error('failed'));
-      await deferred.promise.catch(() => undefined);
-    });
-
-    const unavailable = latest!;
-    await expect(unavailable.mutate(operation)).rejects.toBeInstanceOf(StaleMutationError);
-    expect(operation).not.toHaveBeenCalled();
-    expect(unavailable.canMutate).toBe(false);
-  });
-
-  it('degrades to stale with last-known data when a revalidation fails after success', async () => {
-    let call = 0;
-    const collection = await renderCollection(
-      taskOptions({
-        fetcher: () => {
-          call += 1;
-          return call === 1
-            ? Promise.resolve(taskFixtures)
-            : Promise.reject(new Error('connection lost'));
-        },
-      }),
-    );
-    expect(collection.freshness).toBe('current');
-
-    await act(async () => {
-      await collection.revalidate();
-    });
-
-    expect(latest?.freshness).toBe('stale');
-    expect(latest?.data).toEqual(taskFixtures);
-    const failure: FreshnessFailure | null = latest?.failure ?? null;
-    expect(failure).toEqual({ kind: 'fetch', message: 'connection lost' });
-  });
-});

apps/web/src/lib/freshness/use-fresh-collection.ts

@@ -1,281 +0,0 @@
-import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
-import {
-  acceptSnapshot,
-  assertMutable,
-  computeFreshness,
-  DEFAULT_FRESHNESS_POLICY,
-  invalidationReasonLabels,
-  type FreshPayload,
-  type FreshSnapshot,
-  type FreshnessPolicy,
-  type FreshnessState,
-  type InvalidationReason,
-  StaleMutationError,
-} from './model';
-import { clearSnapshotCache, readSnapshotCache, writeSnapshotCache } from './snapshot-cache';
-
-/**
- * Freshness-aware collection fetch hook (RI-5-001).
- *
- * One hook owns one gateway collection end to end: fetch, schema validation,
- * snapshot acceptance with provenance, session-scoped last-known caching,
- * aging, and the mutation guard. Pages consume `freshness` and never infer
- * health from emptiness.
- */
-
-/** Why the latest validation did not produce a current snapshot. */
-export type FreshnessFailure =
-  | { readonly kind: 'fetch'; readonly message: string }
-  | { readonly kind: 'invalidated'; readonly reason: InvalidationReason };
-
-export interface UseFreshCollectionOptions<T> {
-  /** Source identity for provenance labels, e.g. `gateway:/api/tasks`. */
-  readonly source: string;
-  /** Performs the unvalidated fetch. The hook owns abort and verification. */
-  readonly fetcher: (signal: AbortSignal) => Promise<unknown>;
-  /**
-   * Runtime schema validator. Returning `null` invalidates the payload
-   * (`schema-mismatch`) instead of letting malformed JSON flow into render.
-   */
-  readonly validate: (value: unknown) => FreshPayload<T> | null;
-  /** Overrides of the default freshness policy. */
-  readonly policy?: Partial<FreshnessPolicy>;
-  /**
-   * Session cache key for last-known snapshots. `null`/omitted disables
-   * restore. Restored snapshots are unverified: they render only as
-   * labeled `stale` data until a fetch re-verifies them.
-   */
-  readonly cacheKey?: string | null;
-  /** Injectable clock for deterministic age transitions in tests. */
-  readonly clock?: () => number;
-  /** Aging tick interval override (default derived from `staleAfterMs`). */
-  readonly tickMs?: number;
-  /** When false, no fetch runs (surfaces stay `unavailable`/`unknown`). */
-  readonly enabled?: boolean;
-}
-
-export interface FreshCollection<T> {
-  /** Last verified (or restored-unverified) snapshot, or `null`. */
-  readonly snapshot: FreshSnapshot<T> | null;
-  /** Snapshot data or `null` — never a fabricated empty collection. */
-  readonly data: T | null;
-  readonly freshness: FreshnessState;
-  /** True while a validation request is in flight. */
-  readonly validating: boolean;
-  /** Outcome of the latest failed validation, `null` when healthy. */
-  readonly failure: FreshnessFailure | null;
-  /** False unless freshness is `current`; drives disabled UI affordances. */
-  readonly canMutate: boolean;
-  /** Re-run the fetch and re-verify. Always allowed (it is a read). */
-  readonly revalidate: () => Promise<void>;
-  /**
-   * Run a state-changing operation against verified-current data only.
-   * Rejects with `StaleMutationError` on any other state — the guard fires
-   * even if a disabled button was bypassed (defense in depth).
-   */
-  readonly mutate: <R>(operation: (data: T) => Promise<R>) => Promise<R>;
-}
-
-const defaultClock = (): number => Date.now();
-
-function resolveTickMs(policy: FreshnessPolicy, override?: number): number {
-  if (override !== undefined && override > 0) return override;
-  return Math.min(5_000, Math.max(250, Math.floor(policy.staleAfterMs / 4)));
-}
-
-function isAuthFailure(caught: unknown): boolean {
-  return (
-    typeof caught === 'object' &&
-    caught !== null &&
-    'statusCode' in caught &&
-    ((caught as { statusCode?: unknown }).statusCode === 401 ||
-      (caught as { statusCode?: unknown }).statusCode === 403)
-  );
-}
-
-function fetchFailureMessage(caught: unknown): string {
-  if (caught instanceof Error && caught.message.trim().length > 0) return caught.message;
-  return 'The request failed.';
-}
-
-/** Human-readable summary of a failure for unavailable/stale notices. */
-export function describeFailure(failure: FreshnessFailure | null): string | null {
-  if (failure === null) return null;
-  if (failure.kind === 'fetch') return failure.message;
-  return `The snapshot was invalidated: ${invalidationReasonLabels[failure.reason]}.`;
-}
-
-export function useFreshCollection<T>(options: UseFreshCollectionOptions<T>): FreshCollection<T> {
-  const optionsRef = useRef(options);
-  optionsRef.current = options;
-
-  const policy = useMemo<FreshnessPolicy>(
-    () => ({ ...DEFAULT_FRESHNESS_POLICY, ...options.policy }),
-    [options.policy],
-  );
-  const policyRef = useRef(policy);
-  policyRef.current = policy;
-
-  const clockRef = useRef(options.clock ?? defaultClock);
-  clockRef.current = options.clock ?? defaultClock;
-
-  const [snapshot, setSnapshot] = useState<FreshSnapshot<T> | null>(null);
-  const [failure, setFailure] = useState<FreshnessFailure | null>(null);
-  const [unverified, setUnverified] = useState(false);
-  const [validating, setValidating] = useState(options.enabled !== false);
-  const [now, setNow] = useState(() => (options.clock ?? defaultClock)());
-
-  const snapshotRef = useRef(snapshot);
-  snapshotRef.current = snapshot;
-  const failureRef = useRef(failure);
-  failureRef.current = failure;
-  const unverifiedRef = useRef(unverified);
-  unverifiedRef.current = unverified;
-
-  const runRef = useRef(0);
-  const abortRef = useRef<AbortController | null>(null);
-
-  const revalidate = useCallback(async (): Promise<void> => {
-    const current = optionsRef.current;
-    if (current.enabled === false) {
-      setValidating(false);
-      return;
-    }
-
-    const runId = ++runRef.current;
-    abortRef.current?.abort();
-    const controller = new AbortController();
-    abortRef.current = controller;
-    setValidating(true);
-
-    let value: unknown;
-    try {
-      value = await current.fetcher(controller.signal);
-    } catch (caught) {
-      if (runRef.current !== runId || controller.signal.aborted) return;
-      if (isAuthFailure(caught)) {
-        // An unauthenticated viewer must not keep (or be served) the
-        // previous user's last-known data.
-        setSnapshot(null);
-        setUnverified(false);
-        if (current.cacheKey) clearSnapshotCache(current.cacheKey);
-      }
-      setFailure({ kind: 'fetch', message: fetchFailureMessage(caught) });
-      setValidating(false);
-      return;
-    }
-
-    if (runRef.current !== runId) return;
-
-    const result = acceptSnapshot({
-      value,
-      validate: current.validate,
-      previous: snapshotRef.current,
-      policy: policyRef.current,
-      source: current.source,
-      now: clockRef.current(),
-    });
-
-    if (result.outcome === 'accepted') {
-      setSnapshot(result.snapshot);
-      setUnverified(false);
-      setFailure(null);
-      if (current.cacheKey) writeSnapshotCache(current.cacheKey, result.snapshot);
-    } else {
-      if (result.reason === 'cross-workspace') {
-        // Data verified for a different workspace must not linger as
-        // last-known situational awareness either.
-        setSnapshot(null);
-        setUnverified(false);
-      }
-      if (current.cacheKey) clearSnapshotCache(current.cacheKey);
-      setFailure({ kind: 'invalidated', reason: result.reason });
-    }
-    setValidating(false);
-  }, []);
-
-  // Restore the last-known snapshot (unverified) and run the first fetch.
-  useEffect(() => {
-    if (optionsRef.current.enabled === false) {
-      setValidating(false);
-      return;
-    }
-
-    const cacheKey = optionsRef.current.cacheKey;
-    if (cacheKey) {
-      const restored = readSnapshotCache<T>({
-        key: cacheKey,
-        workspace: policyRef.current.workspace,
-        policy: policyRef.current,
-        validate: optionsRef.current.validate,
-      });
-      if (restored.outcome === 'hit') {
-        setSnapshot(restored.snapshot);
-        setUnverified(true);
-      } else if (restored.outcome === 'invalidated') {
-        // A corrupted/foreign/regressed entry is dropped immediately; it must
-        // never surface as data. The fetch decides the visible state.
-        clearSnapshotCache(cacheKey);
-      }
-    }
-
-    void revalidate();
-
-    return () => {
-      abortRef.current?.abort();
-    };
-    // Mount-once by design: `revalidate` is stable and reads live options
-    // through refs, so it never needs to re-run when options change.
-    // Route-param pages remount this hook via an identity `key` instead.
-  }, [revalidate]);
-
-  // Aging tick: recomputes freshness as the snapshot ages past the policy.
-  useEffect(() => {
-    const interval = setInterval(
-      () => {
-        setNow(clockRef.current());
-      },
-      resolveTickMs(policyRef.current, optionsRef.current.tickMs),
-    );
-    return () => clearInterval(interval);
-  }, []);
-
-  const freshness = useMemo<FreshnessState>(() => {
-    if (snapshot === null) return validating ? 'unknown' : 'unavailable';
-    return computeFreshness({
-      snapshot,
-      policy,
-      now,
-      degraded: failure !== null || unverified,
-    });
-    // `now` from state covers age; refs inside computeFreshness are pure.
-  }, [snapshot, validating, failure, unverified, now, policy]);
-
-  const canMutate = freshness === 'current';
-
-  const mutate = useCallback(async <R>(operation: (data: T) => Promise<R>): Promise<R> => {
-    const currentSnapshot = snapshotRef.current;
-    // No verified snapshot at all: with nothing verified there is nothing
-    // current to mutate, regardless of the recorded failure.
-    if (currentSnapshot === null) throw new StaleMutationError('unavailable');
-    const state = computeFreshness({
-      snapshot: currentSnapshot,
-      policy: policyRef.current,
-      now: clockRef.current(),
-      degraded: failureRef.current !== null || unverifiedRef.current,
-    });
-    assertMutable(state);
-    return operation(currentSnapshot.data);
-  }, []);
-
-  return {
-    snapshot,
-    data: snapshot === null ? null : snapshot.data,
-    freshness,
-    validating,
-    failure,
-    canMutate,
-    revalidate,
-    mutate,
-  };
-}

apps/web/src/lib/freshness/validators.spec.ts

@@ -1,103 +0,0 @@
-import { describe, expect, it } from 'vitest';
-import type { Mission, Project, Task } from '@/lib/types';
-import {
-  validateMissionCollection,
-  validateProjectCollection,
-  validateProjectEntity,
-  validateTaskCollection,
-} from './validators';
-import { missionFixtures, projectFixtures, taskFixtures } from '@/spa/pages/page-fixtures';
-
-describe('validateTaskCollection', () => {
-  it('accepts a well-formed task collection', () => {
-    expect(validateTaskCollection(taskFixtures)).toEqual({
-      data: taskFixtures,
-      workspace: null,
-    });
-  });
-
-  it('accepts an empty collection (a healthy empty state is a valid payload)', () => {
-    expect(validateTaskCollection([])).toEqual({ data: [], workspace: null });
-  });
-
-  it.each([
-    ['not an array', { items: [] }],
-    ['item is not an object', ['nope']],
-    ['missing id', [{ ...(taskFixtures[0] as Task), id: undefined }]],
-    ['missing title', [{ ...(taskFixtures[0] as Task), title: undefined }]],
-    ['unknown status enum', [{ ...(taskFixtures[0] as Task), status: 'finished' }]],
-    ['unknown priority enum', [{ ...(taskFixtures[0] as Task), priority: 'urgent' }]],
-    ['tags of the wrong type', [{ ...(taskFixtures[0] as Task), tags: 'spa' }]],
-    ['metadata of the wrong type', [{ ...(taskFixtures[0] as Task), metadata: 'notes' }]],
-    ['createdAt of the wrong type', [{ ...(taskFixtures[0] as Task), createdAt: 1234 }]],
-    ['null sneaks past a required string', [{ ...(taskFixtures[0] as Task), title: null }]],
-  ])('rejects a malformed payload: %s', (_label, value) => {
-    expect(validateTaskCollection(value)).toBeNull();
-  });
-});
-
-describe('validateMissionCollection', () => {
-  it('accepts a well-formed mission collection', () => {
-    expect(validateMissionCollection(missionFixtures)).toEqual({
-      data: missionFixtures,
-      workspace: null,
-    });
-  });
-
-  it.each([
-    ['not an array', null],
-    ['item missing name', [{ ...(missionFixtures[0] as Mission), name: 42 }]],
-    ['unknown status enum', [{ ...(missionFixtures[0] as Mission), status: 'canceled' }]],
-    ['projectId of the wrong type', [{ ...(missionFixtures[0] as Mission), projectId: 7 }]],
-  ])('rejects a malformed payload: %s', (_label, value) => {
-    expect(validateMissionCollection(value)).toBeNull();
-  });
-});
-
-describe('validateProjectCollection', () => {
-  it('accepts a uniform workspace-scoped collection and reports its workspace', () => {
-    expect(validateProjectCollection(projectFixtures)).toEqual({
-      data: projectFixtures,
-      workspace: 'user-1',
-    });
-  });
-
-  it('accepts an empty collection with no workspace identity', () => {
-    expect(validateProjectCollection([])).toEqual({ data: [], workspace: null });
-  });
-
-  it.each([
-    ['not an array', 42],
-    ['item missing userId', [{ ...(projectFixtures[0] as Project), userId: undefined }]],
-    ['unknown status enum', [{ ...(projectFixtures[0] as Project), status: 'live' }]],
-    ['description of the wrong type', [{ ...(projectFixtures[0] as Project), description: 1 }]],
-  ])('rejects a malformed payload: %s', (_label, value) => {
-    expect(validateProjectCollection(value)).toBeNull();
-  });
-
-  it('rejects a collection mixing workspace identities (cross-workspace leak)', () => {
-    const mixed = [
-      projectFixtures[0] as Project,
-      { ...(projectFixtures[1] as Project), userId: 'user-2' },
-    ];
-    expect(validateProjectCollection(mixed)).toBeNull();
-  });
-});
-
-describe('validateProjectEntity', () => {
-  it('accepts a well-formed project and reports its workspace', () => {
-    expect(validateProjectEntity(projectFixtures[0])).toEqual({
-      data: projectFixtures[0],
-      workspace: 'user-1',
-    });
-  });
-
-  it.each([
-    ['not an object', 'project-1'],
-    ['null', null],
-    ['array', [projectFixtures[0]]],
-    ['missing userId', [{ ...(projectFixtures[0] as Project), userId: null }]],
-  ])('rejects a malformed entity: %s', (_label, value) => {
-    expect(validateProjectEntity(value)).toBeNull();
-  });
-});

apps/web/src/lib/freshness/validators.ts

@@ -1,135 +0,0 @@
-import type { Mission, Project, Task, MissionStatus, TaskPriority, TaskStatus } from '@/lib/types';
-import type { FreshPayload } from './model';
-
-/**
- * Runtime schema validators for gateway collections (RI-5-001).
- *
- * `api<T>()` returns untrusted JSON cast to `T`; these validators are the
- * seam where a malformed response becomes an explicit schema mismatch
- * instead of flowing into the render path as if it were healthy data.
- */
-
-const taskStatuses: readonly TaskStatus[] = [
-  'not-started',
-  'in-progress',
-  'blocked',
-  'done',
-  'cancelled',
-];
-const taskPriorities: readonly TaskPriority[] = ['critical', 'high', 'medium', 'low'];
-const missionStatuses: readonly MissionStatus[] = [
-  'planning',
-  'active',
-  'paused',
-  'completed',
-  'failed',
-];
-const projectStatuses: readonly Project['status'][] = ['active', 'paused', 'completed', 'archived'];
-
-function isRecord(value: unknown): value is Record<string, unknown> {
-  return typeof value === 'object' && value !== null && !Array.isArray(value);
-}
-
-function isString(value: unknown): value is string {
-  return typeof value === 'string';
-}
-
-function isNullableString(value: unknown): value is string | null {
-  return value === null || typeof value === 'string';
-}
-
-function isOneOf<T extends string>(value: unknown, allowed: readonly T[]): value is T {
-  return typeof value === 'string' && (allowed as readonly string[]).includes(value);
-}
-
-function isNullableRecord(value: unknown): value is Record<string, unknown> | null {
-  return value === null || isRecord(value);
-}
-
-function isNullableStringArray(value: unknown): value is string[] | null {
-  if (value === null) return true;
-  if (!Array.isArray(value)) return false;
-  return value.every((item) => typeof item === 'string');
-}
-
-function isIsoLike(value: unknown): value is string {
-  return typeof value === 'string' && value.length > 0;
-}
-
-function isTask(value: unknown): value is Task {
-  if (!isRecord(value)) return false;
-  return (
-    isString(value['id']) &&
-    isString(value['title']) &&
-    isOneOf(value['status'], taskStatuses) &&
-    isOneOf(value['priority'], taskPriorities) &&
-    isNullableString(value['projectId']) &&
-    isNullableString(value['missionId']) &&
-    isNullableString(value['assignee']) &&
-    isNullableStringArray(value['tags']) &&
-    isNullableRecord(value['metadata']) &&
-    isNullableString(value['dueDate']) &&
-    isIsoLike(value['createdAt']) &&
-    isIsoLike(value['updatedAt'])
-  );
-}
-
-/** Tasks carry no workspace identity; scope falls back to the policy. */
-export function validateTaskCollection(value: unknown): FreshPayload<Task[]> | null {
-  if (!Array.isArray(value) || !value.every(isTask)) return null;
-  return { data: value as Task[], workspace: null };
-}
-
-function isMission(value: unknown): value is Mission {
-  if (!isRecord(value)) return false;
-  return (
-    isString(value['id']) &&
-    isString(value['name']) &&
-    isOneOf(value['status'], missionStatuses) &&
-    isNullableString(value['projectId']) &&
-    isNullableString(value['description']) &&
-    isNullableRecord(value['metadata']) &&
-    isIsoLike(value['createdAt']) &&
-    isIsoLike(value['updatedAt'])
-  );
-}
-
-/** Missions carry no workspace identity; scope falls back to the policy. */
-export function validateMissionCollection(value: unknown): FreshPayload<Mission[]> | null {
-  if (!Array.isArray(value) || !value.every(isMission)) return null;
-  return { data: value as Mission[], workspace: null };
-}
-
-function isProject(value: unknown): value is Project {
-  if (!isRecord(value)) return false;
-  return (
-    isString(value['id']) &&
-    isString(value['name']) &&
-    isOneOf(value['status'], projectStatuses) &&
-    isString(value['userId']) &&
-    isNullableString(value['description']) &&
-    isNullableRecord(value['metadata']) &&
-    isIsoLike(value['createdAt']) &&
-    isIsoLike(value['updatedAt'])
-  );
-}
-
-/**
- * Projects are workspace-scoped: every item must carry the same `userId`.
- * A collection mixing identities (cross-workspace leak) is a schema
- * mismatch; the uniform `userId` becomes the snapshot workspace.
- */
-export function validateProjectCollection(value: unknown): FreshPayload<Project[]> | null {
-  if (!Array.isArray(value) || !value.every(isProject)) return null;
-  const projects = value as Project[];
-  const workspaces = new Set(projects.map((project) => project.userId));
-  if (workspaces.size > 1) return null;
-  return { data: projects, workspace: projects.length > 0 ? projects[0]!.userId : null };
-}
-
-/** Single project entity (project detail primary collection). */
-export function validateProjectEntity(value: unknown): FreshPayload<Project> | null {
-  if (!isProject(value)) return null;
-  const project = value as Project;
-  return { data: project, workspace: project.userId };
-}

apps/web/src/spa/pages/project-detail.spec.tsx

@@ -35,7 +35,6 @@ afterEach(async () => {
   document.body.replaceChildren();
   root = null;
   apiMock.mockReset();
-  sessionStorage.clear();
 });
 
 async function renderProjectDetailPage(): Promise<ReturnType<typeof createMemoryRouter>> {
@@ -65,49 +64,21 @@ function clickButtonByText(text: string): void {
   button.dispatchEvent(new MouseEvent('click', { bubbles: true }));
 }
 
-async function flushAct(): Promise<void> {
-  await act(async () => {
-    await Promise.resolve();
-  });
-}
-
-interface Deferred<T> {
-  promise: Promise<T>;
-  resolve: (value: T) => void;
-}
-
-function createDeferred<T>(): Deferred<T> {
-  let resolve!: (value: T) => void;
-  const promise = new Promise<T>((res) => {
-    resolve = res;
-  });
-  return { promise, resolve };
-}
-
-const projectOneTasks = taskFixtures.filter((task) => task.projectId === 'project-1');
-
-function mockHealthyLoad(): void {
-  apiMock
-    .mockResolvedValueOnce(projectFixtures[0])
-    .mockResolvedValueOnce(missionFixtures)
-    .mockResolvedValueOnce(projectOneTasks);
-}
-
 describe('ProjectDetailPage', () => {
   it('loads the project, tasks, missions, and optional PRD content for the active project', async () => {
-    mockHealthyLoad();
+    apiMock
+      .mockResolvedValueOnce(projectFixtures[0])
+      .mockResolvedValueOnce(missionFixtures)
+      .mockResolvedValueOnce(taskFixtures.filter((task) => task.projectId === 'project-1'));
 
     await renderProjectDetailPage();
 
-    expect(apiMock.mock.calls.map((call) => call[0])).toEqual([
-      '/api/projects/project-1',
-      '/api/missions',
-      '/api/tasks?projectId=project-1',
+    expect(apiMock.mock.calls).toEqual([
+      ['/api/projects/project-1'],
+      ['/api/missions'],
+      ['/api/tasks?projectId=project-1'],
     ]);
 
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'current',
-    );
     expect(container.textContent).toContain('Mosaic Stack');
     expect(container.textContent).toContain('Route /projects/:id');
     expect(container.textContent).toContain('Tasks');
@@ -130,7 +101,10 @@ describe('ProjectDetailPage', () => {
   });
 
   it('opens and closes the existing read-only task modal from the tasks tab', async () => {
-    mockHealthyLoad();
+    apiMock
+      .mockResolvedValueOnce(projectFixtures[0])
+      .mockResolvedValueOnce(missionFixtures)
+      .mockResolvedValueOnce(taskFixtures.filter((task) => task.projectId === 'project-1'));
 
     await renderProjectDetailPage();
 
@@ -160,153 +134,35 @@ describe('ProjectDetailPage', () => {
     expect(container.querySelector('[role="dialog"]')).toBeNull();
   });
 
-  it('shows verified completion verdicts when the task collection is current', async () => {
-    mockHealthyLoad();
-
-    await renderProjectDetailPage();
-
-    const doneCard = [...container.querySelectorAll('div')].find(
-      (candidate) => candidate.textContent === 'Done1',
-    );
-    expect(doneCard).toBeTruthy();
-    const inProgressCard = [...container.querySelectorAll('div')].find(
-      (candidate) => candidate.textContent === 'In Progress1',
-    );
-    expect(inProgressCard).toBeTruthy();
-  });
-
-  it('renders an explicit unavailable missions tab when the missions request fails (partial, not empty)', async () => {
+  it('renders the project with an empty missions tab when the missions request fails', async () => {
     apiMock
       .mockResolvedValueOnce(projectFixtures[0])
       .mockRejectedValueOnce(new Error('Missions request failed'))
-      .mockResolvedValueOnce(projectOneTasks);
+      .mockResolvedValueOnce(taskFixtures.filter((task) => task.projectId === 'project-1'));
 
     await renderProjectDetailPage();
 
-    // Secondary failure degrades the surface to partial; the project itself
-    // still renders.
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'partial',
-    );
     expect(container.textContent).toContain('Mosaic Stack');
-    const partial = container.querySelector('[role="status"]');
-    expect(partial?.textContent).toContain('Missions');
-    expect(partial?.textContent).toContain('unavailable');
+    expect(container.querySelector('[role="alert"]')).toBeNull();
 
     await act(async () => {
-      clickButtonByText('Missions (?)');
+      clickButtonByText('Missions (0)');
     });
 
-    const alert = container.querySelector('[role="alert"]');
-    expect(alert?.textContent).toContain('Missions request failed');
-    // Negative control: a failed fetch must not look like an empty list.
-    expect(container.textContent).not.toContain('No missions for this project');
+    expect(container.textContent).toContain('No missions for this project');
   });
 
-  it('marks derived verdicts unknown when the tasks collection is unavailable', async () => {
-    apiMock
-      .mockResolvedValueOnce(projectFixtures[0])
-      .mockResolvedValueOnce(missionFixtures)
-      .mockRejectedValueOnce(new Error('Tasks request failed'));
-
-    await renderProjectDetailPage();
-
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'partial',
-    );
-
-    // Completion verdicts become unknown ('?') — never green counts.
-    for (const label of ['Done', 'In Progress', 'Blocked', 'Tasks']) {
-      const unknownCard = [...container.querySelectorAll('div')].find(
-        (candidate) => candidate.textContent === `${label}?`,
-      );
-      expect(unknownCard, `expected ${label} card to render ?`).toBeTruthy();
-    }
-    // Negative control: no green "Done 1" verdict anywhere.
-    expect(
-      [...container.querySelectorAll('div')].some((candidate) => candidate.textContent === 'Done1'),
-    ).toBe(false);
-
-    await act(async () => {
-      clickButtonByText('Tasks (?)');
-    });
-
-    const alert = container.querySelector('[role="alert"]');
-    expect(alert?.textContent).toContain('Tasks request failed');
-    // Negative control: no healthy empty task list from a failed fetch.
-    expect(container.textContent).not.toContain('No tasks found');
-    expect(container.querySelector('table')).toBeNull();
-  });
-
-  it('recovers a partial surface to current after revalidation', async () => {
-    apiMock
-      .mockResolvedValueOnce(projectFixtures[0])
-      .mockResolvedValueOnce(missionFixtures)
-      .mockRejectedValueOnce(new Error('Tasks request failed'))
-      .mockResolvedValueOnce(projectFixtures[0])
-      .mockResolvedValueOnce(missionFixtures)
-      .mockResolvedValueOnce(projectOneTasks);
-
-    await renderProjectDetailPage();
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'partial',
-    );
-
-    await act(async () => {
-      clickButtonByText('Revalidate');
-    });
-    await flushAct();
-
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'current',
-    );
-    expect(
-      [...container.querySelectorAll('div')].some((candidate) => candidate.textContent === 'Done1'),
-    ).toBe(true);
-  });
-
-  it("never shows one project's data on another project's route after navigation", async () => {
-    mockHealthyLoad();
-
-    const router = await renderProjectDetailPage();
-    expect(container.textContent).toContain('Mosaic Stack');
-
-    const deferred = createDeferred<(typeof projectFixtures)[number]>();
-    apiMock
-      .mockResolvedValueOnce(deferred.promise)
-      .mockResolvedValueOnce([])
-      .mockResolvedValueOnce([]);
-
-    await act(async () => {
-      await router.navigate('/projects/project-2');
-    });
-
-    // While project-2 loads, nothing from project-1 may render on its route.
-    expect(container.textContent).toContain('Loading project...');
-    expect(container.textContent).not.toContain('Mosaic Stack');
-    expect(container.textContent).not.toContain('Route /projects/:id');
-
-    await act(async () => {
-      deferred.resolve(projectFixtures[1]!);
-      await deferred.promise;
-    });
-
-    expect(container.textContent).toContain('Agent Runtime');
-    expect(apiMock.mock.calls[3]?.[0]).toBe('/api/projects/project-2');
-  });
-
-  it('renders a visible unavailable state when the project request fails and lets the user navigate back', async () => {
+  it('renders a visible alert when the project request fails and lets the user navigate back', async () => {
     apiMock
       .mockRejectedValueOnce(new Error('Project request failed'))
       .mockResolvedValueOnce(missionFixtures)
-      .mockResolvedValueOnce(projectOneTasks);
+      .mockResolvedValueOnce(taskFixtures.filter((task) => task.projectId === 'project-1'));
 
     const router = await renderProjectDetailPage();
 
     const alert = container.querySelector('[role="alert"]');
     expect(alert).toBeTruthy();
     expect(alert?.textContent).toContain('Project request failed');
-    expect(alert?.textContent).toContain('not an empty result');
     expect(container.textContent).not.toContain('Mosaic Stack');
 
     await act(async () => {

apps/web/src/spa/pages/project-detail.tsx

@@ -1,30 +1,14 @@
-import { useState, type ReactElement } from 'react';
+import { useEffect, useState, type ReactElement } from 'react';
 import { useNavigate, useParams } from 'react-router-dom';
 import { MissionTimeline } from '@/components/projects/mission-timeline';
 import { PrdViewer } from '@/components/projects/prd-viewer';
 import { TaskDetailModal } from '@/components/tasks/task-detail-modal';
 import { TaskListView } from '@/components/tasks/task-list-view';
 import { TaskStatusSummary } from '@/components/tasks/task-status-summary';
-import {
-  PartialDataNotice,
-  StaleDataNotice,
-  UnavailableDataNotice,
-} from '@/components/freshness/freshness-notices';
 import { api } from '@/lib/api';
 import { cn } from '@/lib/cn';
 import type { Mission, Project, Task, TaskStatus } from '@/lib/types';
-import {
-  combineFreshness,
-  UNKNOWN_VERDICT,
-  verdictValue,
-  type FreshSnapshot,
-} from '@/lib/freshness/model';
-import { describeFailure, useFreshCollection } from '@/lib/freshness/use-fresh-collection';
-import {
-  validateMissionCollection,
-  validateProjectEntity,
-  validateTaskCollection,
-} from '@/lib/freshness/validators';
+import { getErrorMessage } from './page-errors';
 
 type Tab = 'overview' | 'tasks' | 'missions' | 'prd';
 
@@ -67,75 +51,55 @@ function TabButton({ id, label, activeTab, onClick }: TabButtonProps): ReactElem
   );
 }
 
-/** Remounts per project id so no state from one project renders for another. */
 export function ProjectDetailPage(): ReactElement {
   const { id = '' } = useParams();
-  return <ProjectDetail id={id} key={id} />;
-}
-
-function ProjectDetail({ id }: { id: string }): ReactElement {
   const navigate = useNavigate();
-  const enabled = id.length > 0;
-
-  // Primary collection gates the surface; missions and tasks are secondaries
-  // whose failures degrade the surface to `partial` instead of rendering
-  // empty healthy lists.
-  const project = useFreshCollection<Project>({
-    source: `gateway:/api/projects/${id}`,
-    fetcher: (signal) => api<unknown>(`/api/projects/${id}`, { signal }),
-    validate: validateProjectEntity,
-    // No last-known restore: the entity carries workspace identity that
-    // cannot be scope-checked before display (see ProjectsPage note).
-    enabled,
-  });
-  const missions = useFreshCollection<Mission[]>({
-    source: 'gateway:/api/missions',
-    fetcher: (signal) => api<unknown>('/api/missions', { signal }),
-    validate: validateMissionCollection,
-    cacheKey: enabled ? 'missions' : null,
-    enabled,
-  });
-  const tasks = useFreshCollection<Task[]>({
-    source: `gateway:/api/tasks?projectId=${id}`,
-    fetcher: (signal) => api<unknown>(`/api/tasks?projectId=${id}`, { signal }),
-    validate: validateTaskCollection,
-    cacheKey: enabled ? `project-tasks:${id}` : null,
-    enabled,
-  });
-
+  const [project, setProject] = useState<Project | null>(null);
+  const [missions, setMissions] = useState<Mission[]>([]);
+  const [tasks, setTasks] = useState<Task[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
   const [activeTab, setActiveTab] = useState<Tab>('overview');
   const [taskFilter, setTaskFilter] = useState<TaskStatus | 'all'>('all');
   const [selectedTask, setSelectedTask] = useState<Task | null>(null);
 
-  const surface = combineFreshness(project.freshness, [missions.freshness, tasks.freshness]);
-  const tasksVerified = tasks.freshness === 'current';
-  const projectMissions = missions.data?.filter((mission) => mission.projectId === id) ?? null;
+  useEffect(() => {
+    if (!id) {
+      setError('Project id is missing.');
+      setLoading(false);
+      return;
+    }
 
-  const retryAll = (): void => {
-    void Promise.all([project.revalidate(), missions.revalidate(), tasks.revalidate()]);
-  };
+    let cancelled = false;
+    setLoading(true);
+    setError(null);
 
-  if (!enabled) {
-    return (
-      <div className="flex min-h-screen flex-col px-4 py-6 sm:px-6">
-        <header className="mb-6 border-b px-1 pb-3">
-          <h1 className="text-2xl font-semibold">Project</h1>
-        </header>
-        <div role="alert" className="rounded-lg border border-error/40 px-4 py-3 text-sm">
-          Project id is missing.
-        </div>
-        <button
-          type="button"
-          onClick={() => navigate('/projects')}
-          className="mt-4 w-fit text-sm underline"
-        >
-          Back to projects
-        </button>
-      </div>
-    );
-  }
+    void Promise.all([
+      api<Project>('/api/projects/' + id),
+      api<Mission[]>('/api/missions').catch(() => [] as Mission[]),
+      api<Task[]>('/api/tasks?projectId=' + id).catch(() => [] as Task[]),
+    ])
+      .then(([loadedProject, allMissions, loadedTasks]) => {
+        if (cancelled) return;
+        setProject(loadedProject);
+        setMissions(allMissions.filter((mission) => mission.projectId === id));
+        setTasks(loadedTasks);
+      })
+      .catch((caught: unknown) => {
+        if (cancelled) return;
+        setError(getErrorMessage(caught, 'Failed to load project.'));
+      })
+      .finally(() => {
+        if (cancelled) return;
+        setLoading(false);
+      });
 
-  if (project.freshness === 'unknown') {
+    return () => {
+      cancelled = true;
+    };
+  }, [id]);
+
+  if (loading) {
     return (
       <div className="flex min-h-screen flex-col px-4 py-6 sm:px-6">
         <header className="mb-6 border-b px-1 pb-3">
@@ -146,17 +110,15 @@ function ProjectDetail({ id }: { id: string }): ReactElement {
     );
   }
 
-  if (project.freshness === 'unavailable' || project.data === null) {
+  if (error || !project) {
     return (
       <div className="flex min-h-screen flex-col px-4 py-6 sm:px-6">
         <header className="mb-6 border-b px-1 pb-3">
           <h1 className="text-2xl font-semibold">Project</h1>
         </header>
-        <UnavailableDataNotice
-          title="This project"
-          detail={describeFailure(project.failure)}
-          onRetry={retryAll}
-        />
+        <div role="alert" className="rounded-lg border border-error/40 px-4 py-3 text-sm">
+          {error ?? 'Project not found.'}
+        </div>
         <button
           type="button"
           onClick={() => navigate('/projects')}
@@ -168,48 +130,18 @@ function ProjectDetail({ id }: { id: string }): ReactElement {
     );
   }
 
-  const projectTasks = tasks.data ?? null;
   const filteredTasks =
-    projectTasks === null
-      ? []
-      : taskFilter === 'all'
-        ? projectTasks
-        : projectTasks.filter((task) => task.status === taskFilter);
-
-  // Derived completion verdicts: unknown (never green) unless the task
-  // collection is verified current.
-  const doneCount = projectTasks?.filter((task) => task.status === 'done').length ?? 0;
-  const inProgressCount = projectTasks?.filter((task) => task.status === 'in-progress').length ?? 0;
-  const blockedCount = projectTasks?.filter((task) => task.status === 'blocked').length ?? 0;
-
-  const prdContent = getPrdContent(project.data);
+    taskFilter === 'all' ? tasks : tasks.filter((task) => task.status === taskFilter);
+  const prdContent = getPrdContent(project);
   const tabs: Array<{ id: Tab; label: string }> = [
     { id: 'overview', label: 'Overview' },
-    {
-      id: 'tasks',
-      label: `Tasks (${projectTasks === null ? UNKNOWN_VERDICT : projectTasks.length})`,
-    },
-    {
-      id: 'missions',
-      label: `Missions (${projectMissions === null ? UNKNOWN_VERDICT : projectMissions.length})`,
-    },
+    { id: 'tasks', label: `Tasks (${tasks.length})` },
+    { id: 'missions', label: `Missions (${missions.length})` },
     ...(prdContent ? [{ id: 'prd' as const, label: 'PRD' }] : []),
   ];
 
-  const staleSnapshot: FreshSnapshot<unknown> | null =
-    project.freshness === 'stale'
-      ? project.snapshot
-      : missions.freshness === 'stale'
-        ? missions.snapshot
-        : tasks.freshness === 'stale'
-          ? tasks.snapshot
-          : null;
-  const missingSections: string[] = [];
-  if (missions.freshness === 'unavailable') missingSections.push('Missions');
-  if (tasks.freshness === 'unavailable') missingSections.push('Tasks');
-
   return (
-    <div data-freshness={surface} className="flex min-h-screen flex-col px-4 py-6 sm:px-6">
+    <div className="flex min-h-screen flex-col px-4 py-6 sm:px-6">
       <header className="mb-6 border-b px-1 pb-3">
         <nav className="mb-4 flex items-center gap-2 text-sm text-text-muted">
           <button
@@ -220,64 +152,49 @@ function ProjectDetail({ id }: { id: string }): ReactElement {
             Projects
           </button>
           <span>/</span>
-          <span className="text-text-primary">{project.data.name}</span>
+          <span className="text-text-primary">{project.name}</span>
         </nav>
 
         <div className="flex items-start justify-between gap-4">
           <div>
             <div className="flex items-center gap-3">
-              <h1 className="text-2xl font-semibold text-text-primary">{project.data.name}</h1>
+              <h1 className="text-2xl font-semibold text-text-primary">{project.name}</h1>
               <span
                 className={cn(
                   'rounded-full px-2 py-0.5 text-xs',
-                  projectStatusColors[project.data.status] ?? 'bg-gray-600/20 text-gray-400',
+                  projectStatusColors[project.status] ?? 'bg-gray-600/20 text-gray-400',
                 )}
               >
-                {project.data.status}
+                {project.status}
               </span>
             </div>
-            {project.data.description ? (
-              <p className="mt-1 text-sm text-text-muted">{project.data.description}</p>
+            {project.description ? (
+              <p className="mt-1 text-sm text-text-muted">{project.description}</p>
             ) : null}
             <p className="mt-2 text-xs text-text-muted">
-              Created {new Date(project.data.createdAt).toLocaleDateString()} · Updated{' '}
-              {new Date(project.data.updatedAt).toLocaleDateString()}
+              Created {new Date(project.createdAt).toLocaleDateString()} · Updated{' '}
+              {new Date(project.updatedAt).toLocaleDateString()}
             </p>
           </div>
         </div>
       </header>
 
-      {staleSnapshot !== null ? (
-        <div className="mb-6">
-          <StaleDataNotice label={staleSnapshot} onRetry={retryAll} />
-        </div>
-      ) : null}
-
-      {missingSections.length > 0 ? (
-        <div className="mb-6">
-          <PartialDataNotice missing={missingSections} onRetry={retryAll} />
-        </div>
-      ) : null}
-
       <div className="mb-6 grid grid-cols-2 gap-3 sm:grid-cols-4">
-        <StatCard
-          label="Tasks"
-          value={projectTasks === null ? UNKNOWN_VERDICT : String(projectTasks.length)}
-        />
+        <StatCard label="Tasks" value={String(tasks.length)} />
         <StatCard
           label="Done"
-          value={verdictValue(tasksVerified, String(doneCount))}
-          valueClass={tasksVerified ? 'text-success' : undefined}
+          value={String(tasks.filter((task) => task.status === 'done').length)}
+          valueClass="text-success"
         />
         <StatCard
           label="In Progress"
-          value={verdictValue(tasksVerified, String(inProgressCount))}
-          valueClass={tasksVerified ? 'text-blue-400' : undefined}
+          value={String(tasks.filter((task) => task.status === 'in-progress').length)}
+          valueClass="text-blue-400"
         />
         <StatCard
           label="Blocked"
-          value={verdictValue(tasksVerified, String(blockedCount))}
-          valueClass={tasksVerified && blockedCount > 0 ? 'text-error' : undefined}
+          value={String(tasks.filter((task) => task.status === 'blocked').length)}
+          valueClass={tasks.some((task) => task.status === 'blocked') ? 'text-error' : undefined}
         />
       </div>
 
@@ -294,43 +211,23 @@ function ProjectDetail({ id }: { id: string }): ReactElement {
       </div>
 
       {activeTab === 'overview' ? (
-        <OverviewTab project={project.data} missions={projectMissions} tasks={projectTasks} />
+        <OverviewTab project={project} missions={missions} tasks={tasks} />
       ) : null}
 
       {activeTab === 'tasks' ? (
         <div>
-          {projectTasks === null ? (
-            <UnavailableDataNotice
-              title="Tasks"
-              detail={describeFailure(tasks.failure)}
-              onRetry={retryAll}
+          <div className="mb-4">
+            <TaskStatusSummary
+              tasks={tasks}
+              activeFilter={taskFilter}
+              onFilterChange={setTaskFilter}
             />
-          ) : (
-            <>
-              <div className="mb-4">
-                <TaskStatusSummary
-                  tasks={projectTasks}
-                  activeFilter={taskFilter}
-                  onFilterChange={setTaskFilter}
-                />
-              </div>
-              <TaskListView tasks={filteredTasks} onTaskClick={setSelectedTask} />
-            </>
-          )}
+          </div>
+          <TaskListView tasks={filteredTasks} onTaskClick={setSelectedTask} />
         </div>
       ) : null}
 
-      {activeTab === 'missions' ? (
-        projectMissions === null ? (
-          <UnavailableDataNotice
-            title="Missions"
-            detail={describeFailure(missions.failure)}
-            onRetry={retryAll}
-          />
-        ) : (
-          <MissionTimeline missions={projectMissions} />
-        )
-      ) : null}
+      {activeTab === 'missions' ? <MissionTimeline missions={missions} /> : null}
 
       {activeTab === 'prd' && prdContent ? (
         <div className="rounded-lg border border-surface-border bg-surface-card p-6">
@@ -351,26 +248,18 @@ function OverviewTab({
   tasks,
 }: {
   project: Project;
-  missions: Mission[] | null;
-  tasks: Task[] | null;
+  missions: Mission[];
+  tasks: Task[];
 }): ReactElement {
-  const recentTasks =
-    tasks === null
-      ? null
-      : [...tasks]
-          .sort(
-            (left, right) =>
-              new Date(right.updatedAt).getTime() - new Date(left.updatedAt).getTime(),
-          )
-          .slice(0, 5);
+  const recentTasks = [...tasks]
+    .sort((left, right) => new Date(right.updatedAt).getTime() - new Date(left.updatedAt).getTime())
+    .slice(0, 5);
 
   return (
     <div className="grid gap-6 lg:grid-cols-2">
       <section>
         <h2 className="mb-3 text-sm font-semibold text-text-secondary">Recent Tasks</h2>
-        {recentTasks === null ? (
-          <UnavailableDataNotice title="Tasks" />
-        ) : recentTasks.length === 0 ? (
+        {recentTasks.length === 0 ? (
           <div className="rounded-lg border border-surface-border bg-surface-card p-4 text-center">
             <p className="text-sm text-text-muted">No tasks yet</p>
           </div>
@@ -398,9 +287,7 @@ function OverviewTab({
 
       <section>
         <h2 className="mb-3 text-sm font-semibold text-text-secondary">Missions</h2>
-        {missions === null ? (
-          <UnavailableDataNotice title="Missions" />
-        ) : missions.length === 0 ? (
+        {missions.length === 0 ? (
           <div className="rounded-lg border border-surface-border bg-surface-card p-4 text-center">
             <p className="text-sm text-text-muted">No missions yet</p>
           </div>

apps/web/src/spa/pages/projects.spec.tsx

@@ -51,7 +51,6 @@ afterEach(async () => {
   document.body.replaceChildren();
   root = null;
   apiMock.mockReset();
-  sessionStorage.clear();
 });
 
 async function renderProjectsPage(): Promise<ReturnType<typeof createMemoryRouter>> {
@@ -72,22 +71,6 @@ async function renderProjectsPage(): Promise<ReturnType<typeof createMemoryRoute
   return router;
 }
 
-function clickButtonByText(text: string): void {
-  const button = [...container.querySelectorAll('button')].find((candidate) =>
-    candidate.textContent?.includes(text),
-  );
-  if (!button) {
-    throw new Error(`Button containing "${text}" not found`);
-  }
-  button.dispatchEvent(new MouseEvent('click', { bubbles: true }));
-}
-
-async function flushAct(): Promise<void> {
-  await act(async () => {
-    await Promise.resolve();
-  });
-}
-
 describe('ProjectsPage', () => {
   it('shows a visible loading state while the project request is in flight', async () => {
     const deferred = createDeferred<typeof projectFixtures>();
@@ -108,7 +91,7 @@ describe('ProjectsPage', () => {
 
     const router = await renderProjectsPage();
 
-    expect(apiMock.mock.calls[0]?.[0]).toBe('/api/projects');
+    expect(apiMock).toHaveBeenCalledWith('/api/projects');
     expect(container.textContent).toContain('Mosaic Stack');
     expect(container.textContent).toContain('Agent Runtime');
 
@@ -125,7 +108,7 @@ describe('ProjectsPage', () => {
     expect(container.textContent).toContain('Project detail target');
   });
 
-  it('renders the empty state only for a verified empty collection', async () => {
+  it('renders the empty state when the API returns no projects', async () => {
     apiMock.mockResolvedValueOnce([]);
 
     await renderProjectsPage();
@@ -134,12 +117,9 @@ describe('ProjectsPage', () => {
     expect(container.textContent).toContain(
       'Projects will appear here when created via the gateway API',
     );
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'current',
-    );
   });
 
-  it('renders a failed fetch as an explicit unavailable state, never an empty collection', async () => {
+  it('renders a visible alert when the projects request fails', async () => {
     apiMock.mockRejectedValueOnce(new Error('Projects are unavailable'));
 
     await renderProjectsPage();
@@ -147,51 +127,5 @@ describe('ProjectsPage', () => {
     const alert = container.querySelector('[role="alert"]');
     expect(alert).toBeTruthy();
     expect(alert?.textContent).toContain('Projects are unavailable');
-    expect(alert?.textContent).toContain('not an empty result');
-
-    // Negative controls: no healthy empty state and no project cards render
-    // from a failed fetch.
-    expect(container.textContent).not.toContain('No projects yet');
-    expect(container.textContent).not.toContain('Mosaic Stack');
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'unavailable',
-    );
-  });
-
-  it('renders an auth failure as unavailable and recovers after retry', async () => {
-    apiMock
-      .mockRejectedValueOnce(Object.assign(new Error('Unauthorized'), { statusCode: 401 }))
-      .mockResolvedValueOnce(projectFixtures);
-
-    await renderProjectsPage();
-
-    const alert = container.querySelector('[role="alert"]');
-    expect(alert?.textContent).toContain('Unauthorized');
-    expect(container.textContent).not.toContain('No projects yet');
-
-    await act(async () => {
-      clickButtonByText('Retry');
-    });
-    await flushAct();
-
-    expect(container.querySelector('[role="alert"]')).toBeNull();
-    expect(container.textContent).toContain('Mosaic Stack');
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'current',
-    );
-  });
-
-  it('renders a schema-mismatched response as unavailable, never as data', async () => {
-    apiMock.mockResolvedValueOnce({ results: projectFixtures });
-
-    await renderProjectsPage();
-
-    const alert = container.querySelector('[role="alert"]');
-    expect(alert?.textContent).toContain('not an empty result');
-    expect(container.textContent).not.toContain('Mosaic Stack');
-    expect(container.textContent).not.toContain('No projects yet');
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'unavailable',
-    );
   });
 });

apps/web/src/spa/pages/projects.tsx

@@ -1,51 +1,53 @@
-import { type ReactElement } from 'react';
+import { useEffect, useState, type ReactElement } from 'react';
 import { useNavigate } from 'react-router-dom';
 import { ProjectCard } from '@/components/projects/project-card';
-import { StaleDataNotice, UnavailableDataNotice } from '@/components/freshness/freshness-notices';
 import { api } from '@/lib/api';
 import type { Project } from '@/lib/types';
-import { useFreshCollection, describeFailure } from '@/lib/freshness/use-fresh-collection';
-import { validateProjectCollection } from '@/lib/freshness/validators';
+import { getErrorMessage } from './page-errors';
 
 export function ProjectsPage(): ReactElement {
   const navigate = useNavigate();
-  const projects = useFreshCollection<Project[]>({
-    source: 'gateway:/api/projects',
-    fetcher: (signal) => api<unknown>('/api/projects', { signal }),
-    validate: validateProjectCollection,
-    // Projects carry workspace identity (userId) that is only knowable from
-    // the payload itself, so a restored entry cannot be scope-checked before
-    // display. Conservative choice: no last-known restore for this surface;
-    // cross-workspace switching is still invalidated at verification time.
-  });
-  const retry = (): void => {
-    void projects.revalidate();
-  };
+  const [projects, setProjects] = useState<Project[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+
+  useEffect(() => {
+    let cancelled = false;
+
+    void api<Project[]>('/api/projects')
+      .then((response) => {
+        if (cancelled) return;
+        setProjects(response);
+      })
+      .catch((caught: unknown) => {
+        if (cancelled) return;
+        setError(getErrorMessage(caught, 'Failed to load projects.'));
+      })
+      .finally(() => {
+        if (cancelled) return;
+        setLoading(false);
+      });
+
+    return () => {
+      cancelled = true;
+    };
+  }, []);
 
   return (
-    <div
-      data-freshness={projects.freshness}
-      className="flex min-h-screen flex-col px-4 py-6 sm:px-6"
-    >
+    <div className="flex min-h-screen flex-col px-4 py-6 sm:px-6">
       <header className="mb-6 border-b px-1 pb-3">
         <h1 className="text-2xl font-semibold">Projects</h1>
       </header>
 
-      {projects.freshness === 'stale' && projects.snapshot ? (
-        <div className="mb-6">
-          <StaleDataNotice label={projects.snapshot} onRetry={retry} />
+      {error ? (
+        <div role="alert" className="mb-6 rounded-lg border border-error/40 px-4 py-3 text-sm">
+          {error}
         </div>
       ) : null}
 
-      {projects.freshness === 'unknown' ? (
+      {loading ? (
         <p className="py-8 text-center text-sm text-text-muted">Loading projects...</p>
-      ) : projects.freshness === 'unavailable' ? (
-        <UnavailableDataNotice
-          title="Projects"
-          detail={describeFailure(projects.failure)}
-          onRetry={retry}
-        />
-      ) : projects.data !== null && projects.data.length === 0 ? (
+      ) : projects.length === 0 ? (
         <div className="py-12 text-center">
           <h2 className="text-lg font-medium text-text-secondary">No projects yet</h2>
           <p className="mt-1 text-sm text-text-muted">
@@ -54,7 +56,7 @@ export function ProjectsPage(): ReactElement {
         </div>
       ) : (
         <div className="grid gap-4 sm:grid-cols-2 lg:grid-cols-3">
-          {(projects.data ?? []).map((project) => (
+          {projects.map((project) => (
             <ProjectCard
               key={project.id}
               project={project}

apps/web/src/spa/pages/tasks.spec.tsx

@@ -3,9 +3,6 @@ import { createRoot, type Root } from 'react-dom/client';
 import { createMemoryRouter, RouterProvider, type RouteObject } from 'react-router-dom';
 import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from 'vitest';
 import { taskFixtures } from './page-fixtures';
-import { acceptSnapshot, DEFAULT_FRESHNESS_POLICY } from '@/lib/freshness/model';
-import { writeSnapshotCache } from '@/lib/freshness/snapshot-cache';
-import { validateTaskCollection } from '@/lib/freshness/validators';
 
 const { apiMock } = vi.hoisted(() => ({
   apiMock: vi.fn(),
@@ -51,7 +48,6 @@ afterEach(async () => {
   document.body.replaceChildren();
   root = null;
   apiMock.mockReset();
-  sessionStorage.clear();
 });
 
 async function renderTasksPage(): Promise<void> {
@@ -76,13 +72,6 @@ function clickButtonByText(text: string): void {
   button.dispatchEvent(new MouseEvent('click', { bubbles: true }));
 }
 
-/** Flush pending promise callbacks inside the act environment. */
-async function flushAct(): Promise<void> {
-  await act(async () => {
-    await Promise.resolve();
-  });
-}
-
 describe('TasksPage', () => {
   it('shows a visible loading state before the tasks request settles', async () => {
     const deferred = createDeferred<typeof taskFixtures>();
@@ -143,7 +132,7 @@ describe('TasksPage', () => {
     expect(container.textContent).toContain('Wire list and kanban modal interactions');
   });
 
-  it('renders a failed fetch as an explicit unavailable state, never an empty healthy board', async () => {
+  it('renders a visible alert when the tasks request fails', async () => {
     apiMock.mockRejectedValueOnce(new Error('Tasks request failed'));
 
     await renderTasksPage();
@@ -151,80 +140,5 @@ describe('TasksPage', () => {
     const alert = container.querySelector('[role="alert"]');
     expect(alert).toBeTruthy();
     expect(alert?.textContent).toContain('Tasks request failed');
-    expect(alert?.textContent).toContain('not an empty result');
-
-    // Negative controls: no board, no healthy empty-state markers, and the
-    // surface is marked unavailable rather than current.
-    expect(container.textContent).not.toContain('Not Started');
-    expect(container.textContent).not.toContain('No tasks');
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'unavailable',
-    );
-  });
-
-  it('recovers to a current board after retrying a failed fetch', async () => {
-    apiMock
-      .mockRejectedValueOnce(new Error('Tasks request failed'))
-      .mockResolvedValueOnce(taskFixtures);
-
-    await renderTasksPage();
-    expect(container.querySelector('[role="alert"]')).toBeTruthy();
-
-    await act(async () => {
-      clickButtonByText('Retry');
-    });
-    await flushAct();
-
-    expect(container.querySelector('[role="alert"]')).toBeNull();
-    expect(container.textContent).toContain('Not Started');
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'current',
-    );
-  });
-
-  it('labels restored last-known data as stale with source, version, and age until verified', async () => {
-    // Seed a last-known snapshot fetched five minutes ago; the page must
-    // render it only under an explicit staleness label while the fetch is
-    // still in flight.
-    const restored = acceptSnapshot({
-      value: taskFixtures,
-      validate: validateTaskCollection,
-      previous: null,
-      policy: DEFAULT_FRESHNESS_POLICY,
-      source: 'gateway:/api/tasks',
-      now: Date.now() - 5 * 60_000,
-    });
-    if (restored.outcome !== 'accepted') throw new Error('fixture setup failed');
-    writeSnapshotCache('tasks', restored.snapshot);
-
-    const deferred = createDeferred<typeof taskFixtures>();
-    apiMock.mockReturnValueOnce(deferred.promise);
-
-    await renderTasksPage();
-
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'stale',
-    );
-    const banner = container.querySelector('[role="status"]');
-    expect(banner?.textContent).toContain('last-known');
-    expect(banner?.textContent).toContain('may be out of date');
-    expect(banner?.textContent).toContain('gateway:/api/tasks');
-    expect(banner?.textContent).toContain('snapshot v1');
-    expect(banner?.textContent).toContain('5m ago');
-
-    // Last-known data still renders as situational awareness under the label.
-    expect(container.textContent).toContain('Route /tasks');
-    expect(container.textContent).not.toContain('Loading tasks...');
-
-    // Verification lands: the banner clears and the surface becomes current.
-    await act(async () => {
-      deferred.resolve(taskFixtures);
-      await deferred.promise;
-    });
-
-    expect(container.querySelector('[role="status"]')).toBeNull();
-    expect(container.querySelector('[data-freshness]')?.getAttribute('data-freshness')).toBe(
-      'current',
-    );
   });
 });

apps/web/src/spa/pages/tasks.tsx

@@ -1,32 +1,45 @@
-import { useState, type ReactElement } from 'react';
+import { useEffect, useState, type ReactElement } from 'react';
 import { KanbanBoard } from '@/components/tasks/kanban-board';
 import { TaskDetailModal } from '@/components/tasks/task-detail-modal';
 import { TaskListView } from '@/components/tasks/task-list-view';
-import { StaleDataNotice, UnavailableDataNotice } from '@/components/freshness/freshness-notices';
 import { api } from '@/lib/api';
 import { cn } from '@/lib/cn';
 import type { Task } from '@/lib/types';
-import { useFreshCollection, describeFailure } from '@/lib/freshness/use-fresh-collection';
-import { validateTaskCollection } from '@/lib/freshness/validators';
+import { getErrorMessage } from './page-errors';
 
 type ViewMode = 'list' | 'kanban';
 
 export function TasksPage(): ReactElement {
-  const tasks = useFreshCollection<Task[]>({
-    source: 'gateway:/api/tasks',
-    fetcher: (signal) => api<unknown>('/api/tasks', { signal }),
-    validate: validateTaskCollection,
-    cacheKey: 'tasks',
-  });
+  const [tasks, setTasks] = useState<Task[]>([]);
   const [view, setView] = useState<ViewMode>('kanban');
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
   const [selectedTask, setSelectedTask] = useState<Task | null>(null);
 
-  const retry = (): void => {
-    void tasks.revalidate();
-  };
+  useEffect(() => {
+    let cancelled = false;
+
+    void api<Task[]>('/api/tasks')
+      .then((response) => {
+        if (cancelled) return;
+        setTasks(response);
+      })
+      .catch((caught: unknown) => {
+        if (cancelled) return;
+        setError(getErrorMessage(caught, 'Failed to load tasks.'));
+      })
+      .finally(() => {
+        if (cancelled) return;
+        setLoading(false);
+      });
+
+    return () => {
+      cancelled = true;
+    };
+  }, []);
 
   return (
-    <div data-freshness={tasks.freshness} className="flex min-h-screen flex-col px-4 py-6 sm:px-6">
+    <div className="flex min-h-screen flex-col px-4 py-6 sm:px-6">
       <header className="mb-6 flex items-center justify-between gap-4 border-b px-1 pb-3">
         <h1 className="text-2xl font-semibold">Tasks</h1>
         <div className="flex rounded-lg border border-surface-border">
@@ -57,24 +70,18 @@ export function TasksPage(): ReactElement {
         </div>
       </header>
 
-      {tasks.freshness === 'stale' && tasks.snapshot ? (
-        <div className="mb-6">
-          <StaleDataNotice label={tasks.snapshot} onRetry={retry} />
+      {error ? (
+        <div role="alert" className="mb-6 rounded-lg border border-error/40 px-4 py-3 text-sm">
+          {error}
         </div>
       ) : null}
 
-      {tasks.freshness === 'unknown' ? (
+      {loading ? (
         <p className="py-8 text-center text-sm text-text-muted">Loading tasks...</p>
-      ) : tasks.freshness === 'unavailable' ? (
-        <UnavailableDataNotice
-          title="Tasks"
-          detail={describeFailure(tasks.failure)}
-          onRetry={retry}
-        />
       ) : view === 'kanban' ? (
-        <KanbanBoard tasks={tasks.data ?? []} onTaskClick={setSelectedTask} />
+        <KanbanBoard tasks={tasks} onTaskClick={setSelectedTask} />
       ) : (
-        <TaskListView tasks={tasks.data ?? []} onTaskClick={setSelectedTask} />
+        <TaskListView tasks={tasks} onTaskClick={setSelectedTask} />
       )}
 
       {selectedTask ? (

packages/mosaic/framework/tools/fleet/start-agent-session.sh

@@ -233,8 +233,36 @@ assert_owned_tmux_server() {
     fail "tmux server ownership or environment validation failed"
 }
 
-# Validate exact server ownership before querying, cleaning, or creating any
-# managed session. An unmanaged or contaminated named socket is never repaired.
+# Lease-broker socket preflight (#1292). The gated runtime (`mosaic yolo …` →
+# launch-runtime.py) registers with the broker or dies ~4 seconds in, with the
+# diagnostic invisible because tmux destroys the dead pane. This check runs
+# BEFORE any tmux effect — including the ownership probe below — so a host
+# without a broker produces a named, surviving refusal instead of a doomed
+# pane. Exit 75 (EX_TEMPFAIL), distinct from 64 (bad projection) and 69 (host
+# not ready for other reasons); the agent@ unit is Type=oneshot with no
+# Restart=, so the failed unit keeps its message instead of looping. Socket
+# resolution matches launch.ts's defaultLeaseBrokerSocket precedence exactly.
+# This preflight DETECTS and REFUSES — it never starts the broker (activation
+# belongs to the fleet control plane; a component that both detects and fixes
+# cannot be used to measure whether the fix worked).
+broker_socket_path() {
+  if [ -n "${MOSAIC_LEASE_BROKER_SOCKET:-}" ]; then
+    printf '%s\n' "$MOSAIC_LEASE_BROKER_SOCKET"
+    return 0
+  fi
+  local runtime_dir="${XDG_RUNTIME_DIR:-/run/user/$(id -u)}"
+  printf '%s\n' "${runtime_dir}/mosaic-lease/broker.sock"
+}
+
+if [ "$MODE" = "launch" ]; then
+  _broker_socket=$(broker_socket_path)
+  if [ ! -S "$_broker_socket" ]; then
+    echo "[fleet] FAIL_LAUNCH broker-absent: lease broker socket ${_broker_socket} missing; runtime launch denied (#1292)." >&2
+    echo "[fleet] remedy: systemctl --user enable --now mosaic-lease-broker.service  (or reinstall via: mosaic fleet install)" >&2
+    exit 75
+  fi
+fi
+
 assert_owned_tmux_server
 
 if [ "$MODE" = interaction ]; then

packages/mosaic/framework/tools/fleet/test-agent-session-broker-preflight.sh

@@ -0,0 +1,216 @@
+#!/usr/bin/env bash
+# CI-fit regression suite for the #1292 lease-broker socket preflight in
+# start-agent-session.sh.
+#
+# WHY THIS SUITE IS CI-FIT WHERE test-start-agent-session.sh IS NOT (#1017/#1270
+# context): that older suite's precondition is "the host does not have the pi
+# binary", which a CI image that ships pi violates — its guard correctly
+# refuses to report a pass there, so it is excluded from the chain. THIS suite
+# controls its own preconditions instead of inheriting them from the host: a
+# fake tmux on PATH, a fake mosaic on PATH, a real unix socket created in a
+# tmpdir, a hermetic env (env -i, fake HOME, GIT_CONFIG_GLOBAL severed). It
+# never depends on what the host has installed, so a green here means the same
+# thing on every host. Anyone adding cases: keep that property — no case may
+# depend on host state.
+#
+# The failure this suite is written down to catch (#1292): a seat launched on a
+# host with no lease broker dies ~4 seconds in at registration, with the
+# diagnostic invisible because tmux destroys the dead pane. The preflight runs
+# BEFORE any tmux effect and refuses with a NAMED code (exit 75, EX_TEMPFAIL)
+# so the message survives. The agent@ unit is Type=oneshot with no Restart=,
+# so a failed unit keeps its output instead of looping.
+#
+# Cases:
+#   1. absent socket -> exit 75, message names broker-absent + socket path +
+#      remedy, and NO tmux session was ever created (the doomed-pane half).
+#   2. present socket (real unix socket in tmpdir) -> proceeds PAST the
+#      preflight (the suite then stops at the next precondition, proving the
+#      preflight was not the refusal).
+#   3. explicit MOSAIC_LEASE_BROKER_SOCKET wins over XDG_RUNTIME_DIR default.
+#   4. --stop mode does NOT require the broker (teardown must not be fenced on
+#      a component whose absence is exactly what teardown may follow).
+#
+# Sabotage control, run by the developer (not in-suite): remove the preflight
+# block from start-agent-session.sh, re-run — case 1 fails (a tmux session is
+# created / exit is not 75), cases 2-4 still pass; restore byte-identically.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+WORK_DIR="${MOSAIC_TEST_WORK_DIR:-$PWD/.mosaic-test-work/agent-session-broker-preflight}"
+FAKE_HOME="$WORK_DIR/home"
+BIN_DIR="$WORK_DIR/bin"
+ENV_DIR="$WORK_DIR/env"
+SOCK_DIR="$WORK_DIR/sockets"
+LOG_FILE="$WORK_DIR/tmux-calls.log"
+
+rm -rf "$WORK_DIR"
+# The script asserts a managed directory tree under MOSAIC_HOME: mosaic/,
+# mosaic/fleet/, mosaic/fleet/agents/ — private (0700/0750-style) modes, no
+# symlinks — plus a per-agent env projection. Build the full tree the launcher
+# expects so the suite reaches the BROKER preflight rather than dying at
+# environment validation.
+mkdir -p "$FAKE_HOME/.config/mosaic/fleet/agents" "$BIN_DIR" "$SOCK_DIR"
+chmod 700 "$FAKE_HOME/.config/mosaic" "$FAKE_HOME/.config/mosaic/fleet/agents"
+chmod 750 "$FAKE_HOME/.config/mosaic/fleet"
+cat > "$FAKE_HOME/.config/mosaic/fleet/agents/preflight-test.env.generated" <<'ENVEOF'
+MOSAIC_AGENT_NAME=preflight-test
+MOSAIC_AGENT_CLASS=worker
+MOSAIC_AGENT_RUNTIME=pi
+MOSAIC_AGENT_MODEL=
+MOSAIC_AGENT_REASONING=
+MOSAIC_AGENT_TOOL_POLICY=code
+MOSAIC_AGENT_WORKDIR=/tmp
+MOSAIC_TMUX_SOCKET=mosaic-fleet
+ENVEOF
+chmod 600 "$FAKE_HOME/.config/mosaic/fleet/agents/preflight-test.env.generated"
+
+# ─── Fake tmux: records every invocation; new-session marks the marker. ────
+: > "$LOG_FILE"
+cat > "$BIN_DIR/tmux" <<SH
+#!/usr/bin/env bash
+printf 'tmux %s\n' "\$*" >> "$LOG_FILE"
+if [[ "\$*" == *new-session* ]]; then
+  echo "TMUX-NEW-SESSION-INVOKED" >> "$LOG_FILE"
+fi
+exit 0
+SH
+chmod +x "$BIN_DIR/tmux"
+
+# ─── Fake mosaic/pi binaries so the script proceeds past its own lookups. ───
+for bin in mosaic pi claude; do
+  printf '#!/usr/bin/env bash\nexit 0\n' > "$BIN_DIR/$bin"
+  chmod +x "$BIN_DIR/$bin"
+done
+
+# ─── Minimal launch environment the script expects. ────────────────────────
+# (Enough for the preflight to be reached; later stages will still fail in
+# case 2 — that is expected and asserted.)
+run_session_script() {
+  local mode="$1"; shift
+  (
+    cd "$WORK_DIR"
+    env -i HOME="$FAKE_HOME" PATH="$BIN_DIR:/usr/bin:/bin" \
+      GIT_CONFIG_GLOBAL=/dev/null GIT_CONFIG_SYSTEM=/dev/null \
+      MOSAIC_HOME="$FAKE_HOME/.config/mosaic" \
+      AGENT_NAME=preflight-test \
+      "$@" \
+      bash "$SCRIPT_DIR/start-agent-session.sh" $mode preflight-test
+  )
+}
+
+fail=0
+assert() {
+  local desc="$1" expected="$2" actual="$3"
+  if [[ "$expected" != "$actual" ]]; then
+    echo "FAIL: $desc — expected '$expected', got '$actual'" >&2
+    fail=1
+  fi
+}
+assert_contains() {
+  local desc="$1" haystack="$2" needle="$3"
+  [[ "$haystack" == *"$needle"* ]] || { echo "FAIL: $desc — missing '$needle' in: $haystack" >&2; fail=1; }
+}
+assert_not_contains() {
+  local desc="$1" haystack="$2" needle="$3"
+  if [[ "$haystack" == *"$needle"* ]]; then
+    echo "FAIL: $desc — must not contain '$needle'" >&2
+    fail=1
+  fi
+  return 0
+}
+
+# ─── 1. Absent socket → named refusal, NO tmux session. ────────────────────
+: > "$LOG_FILE"
+stderr_file="$WORK_DIR/stderr-1.tmp"
+set +e
+out=$(run_session_script "" MOSAIC_LEASE_BROKER_SOCKET="$SOCK_DIR/absent.sock" 2>"$stderr_file")
+rc=$?
+set -e
+assert "absent socket exit code" "75" "$rc"
+err=$(cat "$stderr_file")
+assert_contains "absent socket names the failure" "$err" "FAIL_LAUNCH broker-absent"
+assert_contains "absent socket names the socket path" "$err" "$SOCK_DIR/absent.sock"
+assert_contains "absent socket names a remedy" "$err" "mosaic fleet install"
+log1=$(cat "$LOG_FILE")
+assert_not_contains "absent socket must not create a tmux session" "$log1" "TMUX-NEW-SESSION-INVOKED"
+
+# ─── 2. Present socket → passes the preflight. ─────────────────────────────
+# Expected: ownership/env checks AFTER the preflight may refuse (fixture is
+# minimal by design); the assertion is only that the refusal is NOT
+# broker-absent and the exit is NOT 75.
+# Create a REAL unix socket: a detached python holder binds it and stays alive
+# for the duration (bash cannot create sockets; a foreground python would
+# close the socket on exit and -S on a closed-but-unlinked path fails). Written
+# as a script file + setsid nohup so no job-control/heredoc interaction with
+# set -e can silently kill the suite.
+# AF_UNIX binds cap at 108 path bytes; the suite's workdir exceeds that, so
+# the live socket lives at a SHORT path under /tmp (unique per run, cleaned
+# with the suite). The preflight takes its socket path explicitly, so this
+# stays fully controlled.
+LIVE_SOCK=$(mktemp -u /tmp/mosaic-preflight-XXXXXX.sock)
+trap 'rm -f "$LIVE_SOCK"' EXIT
+rm -f "$SOCK_DIR/live.sock" "$LIVE_SOCK"
+cat > "$SOCK_DIR/holder.py" <<'PY'
+import socket, sys, time
+path = sys.argv[1]
+s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+s.bind(path)
+s.listen(1)
+time.sleep(120)
+PY
+python3 "$SOCK_DIR/holder.py" "$LIVE_SOCK" >/dev/null 2>"$SOCK_DIR/holder.err" &
+HOLDER_PID=$!
+# Wait for the socket object to exist (bind is near-instant, but do not race it).
+for _ in $(seq 1 50); do
+  [ -S "$LIVE_SOCK" ] && break
+  sleep 0.1
+done
+if [ ! -S "$LIVE_SOCK" ]; then
+  echo "FAIL: could not create live socket fixture (holder pid $HOLDER_PID)" >&2
+  ps -p "$HOLDER_PID" -o pid,stat,cmd --no-headers >&2 || echo "(holder exited)" >&2
+  cat "$SOCK_DIR/holder.err" >&2 || true
+  exit 1
+fi
+: > "$LOG_FILE"
+set +e
+out=$(run_session_script "" MOSAIC_LEASE_BROKER_SOCKET="$LIVE_SOCK" 2>"$WORK_DIR/stderr-2.tmp")
+rc=$?
+set -e
+# The preflight PASSED if the failure (whatever later stage refused) is NOT
+# the broker refusal, and tmux was reached or a later precondition named
+# something else.
+err2=$(cat "$WORK_DIR/stderr-2.tmp")
+assert_not_contains "live socket must not refuse broker-absent" "$err2" "broker-absent"
+if [[ "$rc" == "75" ]]; then
+  echo "FAIL: live socket — preflight still refused (exit 75) with a live socket" >&2
+  fail=1
+fi
+
+# ─── 3. Explicit socket env wins over XDG default. ─────────────────────────
+set +e
+out=$(run_session_script "" XDG_RUNTIME_DIR="$SOCK_DIR/no-runtime-here" MOSAIC_LEASE_BROKER_SOCKET="$SOCK_DIR/absent2.sock" 2>"$WORK_DIR/stderr-3.tmp")
+rc=$?
+set -e
+assert "explicit env wins (exit 75)" "75" "$rc"
+assert_contains "explicit env path named" "$(cat "$WORK_DIR/stderr-3.tmp")" "$SOCK_DIR/absent2.sock"
+
+# ─── 4. --stop is not fenced on the broker. ────────────────────────────────
+: > "$LOG_FILE"
+set +e
+out=$(run_session_script "--stop" MOSAIC_LEASE_BROKER_SOCKET="$SOCK_DIR/absent3.sock" 2>"$WORK_DIR/stderr-4.tmp")
+rc=$?
+set -e
+err4=$(cat "$WORK_DIR/stderr-4.tmp")
+assert_not_contains "--stop must not refuse broker-absent" "$err4" "broker-absent"
+if [[ "$rc" == "75" ]]; then
+  echo "FAIL: --stop — exit 75 means teardown was fenced on the broker" >&2
+  fail=1
+fi
+
+kill "$HOLDER_PID" 2>/dev/null || true
+
+if [[ "$fail" -eq 0 ]]; then
+  echo "start-agent-session lease-broker preflight regression passed"
+fi
+exit "$fail"

packages/mosaic/src/commands/fleet-place-unit.spec.ts

@@ -0,0 +1,177 @@
+import { lstat, mkdir, mkdtemp, readFile, rm, symlink, writeFile } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { afterEach, describe, expect, it } from 'vitest';
+
+import { placeUnitFile, resolveLeaseBrokerSocketForPreflight } from './fleet.js';
+
+/**
+ * Unit-placement regression harness for #1292.
+ *
+ * The two measured defects this suite pins:
+ *  1. `systemctl enable <name>` does NOT rewrite an existing by-path
+ *     wants-symlink — so placement must remove stale residue explicitly, and
+ *     acceptance asserts on the RESULTING SYMLINK TARGET, never on the enable
+ *     call's argument (asserting the call cannot see where the link ended up).
+ *  2. Node's copyFile FOLLOWS a by-path symlink at the destination and
+ *     overwrites the SEED template. Acceptance asserts on the SEED's bytes
+ *     AND mtime — unchanged — which is the only check that can redden for
+ *     finding 2. The symlink-target assertion catches finding 1; these are
+ *     different defects with different failure modes.
+ *
+ * Fixtures are entirely inside tmpdirs (source template, active systemd dir,
+ * wants dir) — no real host paths are touched by this suite.
+ */
+
+describe('placeUnitFile (#1292 unit placement)', () => {
+  const cleanup: string[] = [];
+  afterEach(async () => {
+    while (cleanup.length > 0) {
+      await rm(cleanup.pop()!, { recursive: true, force: true });
+    }
+  });
+
+  async function fixture() {
+    const root = await mkdtemp(join(tmpdir(), 'place-unit-'));
+    cleanup.push(root);
+    const seedDir = join(root, 'seed');
+    const activeDir = join(root, 'active');
+    await mkdir(seedDir, { recursive: true });
+    await mkdir(activeDir, { recursive: true });
+    const seedTemplate = join(seedDir, 'unit-under-test.service');
+    await writeFile(
+      seedTemplate,
+      '[Unit]\nDescription=seed template\n[Service]\nType=oneshot\nExecStart=/bin/true\n[Install]\nWantedBy=default.target\n',
+    );
+    const activeSource = join(root, 'active-source.service');
+    await writeFile(
+      activeSource,
+      '[Unit]\nDescription=active copy v2\n[Service]\nType=oneshot\nExecStart=/bin/true\n[Install]\nWantedBy=default.target\n',
+    );
+    return { root, seedDir, activeDir, seedTemplate, activeSource };
+  }
+
+  it('places a regular file on a clean host (negative control: no residue anywhere)', async () => {
+    const f = await fixture();
+    const result = await placeUnitFile(f.activeSource, f.activeDir, 'unit-under-test.service');
+    expect(result.unlinkedDestinationSymlink).toBe(false);
+    expect(result.removedStaleWantsSymlink).toBe(false);
+    const info = await lstat(join(f.activeDir, 'unit-under-test.service'));
+    expect(info.isSymbolicLink()).toBe(false);
+    expect(await readFile(join(f.activeDir, 'unit-under-test.service'), 'utf8')).toContain(
+      'active copy v2',
+    );
+    // Seed untouched by construction — but assert it, so the clean-host case
+    // cannot silently regress into seed-mutation.
+    expect(await readFile(f.seedTemplate, 'utf8')).toContain('seed template');
+  });
+
+  it('by-path residue: unlinks destination symlink, places the file, seed bytes AND mtime unchanged (finding 2)', async () => {
+    const f = await fixture();
+    const seedBefore = await readFile(f.seedTemplate, 'utf8');
+    const mtimeBefore = (await lstat(f.seedTemplate)).mtimeMs;
+    // The fomo-lin convention: by-path enable left a symlink AT the unit name
+    // pointing at the seed template, plus a wants-symlink doing the same.
+    await symlink(f.seedTemplate, join(f.activeDir, 'unit-under-test.service'));
+    const wantsDir = join(f.activeDir, 'default.target.wants');
+    await mkdir(wantsDir, { recursive: true });
+    await symlink(f.seedTemplate, join(wantsDir, 'unit-under-test.service'));
+
+    const result = await placeUnitFile(f.activeSource, f.activeDir, 'unit-under-test.service');
+    expect(result.unlinkedDestinationSymlink).toBe(true);
+    expect(result.removedStaleWantsSymlink).toBe(true);
+
+    // FINDING 2's check: the seed is byte-identical and its mtime did not move.
+    expect(await readFile(f.seedTemplate, 'utf8')).toBe(seedBefore);
+    expect((await lstat(f.seedTemplate)).mtimeMs).toBe(mtimeBefore);
+
+    // The destination is now a regular file carrying the ACTIVE content.
+    const destInfo = await lstat(join(f.activeDir, 'unit-under-test.service'));
+    expect(destInfo.isSymbolicLink()).toBe(false);
+    expect(await readFile(join(f.activeDir, 'unit-under-test.service'), 'utf8')).toContain(
+      'active copy v2',
+    );
+  });
+
+  it('by-path residue: no wants-symlink remains pointing at the seed (finding 1 residue cleared)', async () => {
+    const f = await fixture();
+    await symlink(f.seedTemplate, join(f.activeDir, 'unit-under-test.service'));
+    const wantsDir = join(f.activeDir, 'default.target.wants');
+    await mkdir(wantsDir, { recursive: true });
+    await symlink(f.seedTemplate, join(wantsDir, 'unit-under-test.service'));
+
+    await placeUnitFile(f.activeSource, f.activeDir, 'unit-under-test.service');
+
+    // After placement the stale wants link is GONE (enable-by-name recreates
+    // it correctly). A link still present must not point at the seed.
+    try {
+      const link = await lstat(join(wantsDir, 'unit-under-test.service'));
+      if (link.isSymbolicLink()) {
+        const target = await readFile(join(wantsDir, 'unit-under-test.service'), 'utf8').catch(
+          async () => '',
+        );
+        expect(target).not.toContain('seed template');
+      }
+    } catch {
+      // absent wants link — the expected post-placement state
+    }
+  });
+
+  it('idempotence: second placement on a reconciled host is a no-op producing the identical final state', async () => {
+    const f = await fixture();
+    // Reconciled starting state: regular file at the name, wants link to the active copy.
+    await writeFile(
+      join(f.activeDir, 'unit-under-test.service'),
+      await readFile(f.activeSource, 'utf8'),
+    );
+    const wantsDir = join(f.activeDir, 'default.target.wants');
+    await mkdir(wantsDir, { recursive: true });
+    await symlink(
+      join(f.activeDir, 'unit-under-test.service'),
+      join(wantsDir, 'unit-under-test.service'),
+    );
+    const before = await readFile(join(f.activeDir, 'unit-under-test.service'), 'utf8');
+
+    const result = await placeUnitFile(f.activeSource, f.activeDir, 'unit-under-test.service');
+    // No destructive step fired: no unlink, no wants removal.
+    expect(result.unlinkedDestinationSymlink).toBe(false);
+    expect(result.removedStaleWantsSymlink).toBe(false);
+    // Identical final state.
+    expect(await readFile(join(f.activeDir, 'unit-under-test.service'), 'utf8')).toBe(before);
+    const link = await lstat(join(wantsDir, 'unit-under-test.service'));
+    expect(link.isSymbolicLink()).toBe(true);
+  });
+
+  it('double install on by-path residue converges to the identical reconciled state', async () => {
+    const f = await fixture();
+    await symlink(f.seedTemplate, join(f.activeDir, 'unit-under-test.service'));
+    const wantsDir = join(f.activeDir, 'default.target.wants');
+    await mkdir(wantsDir, { recursive: true });
+    await symlink(f.seedTemplate, join(wantsDir, 'unit-under-test.service'));
+
+    await placeUnitFile(f.activeSource, f.activeDir, 'unit-under-test.service');
+    const first = await readFile(join(f.activeDir, 'unit-under-test.service'), 'utf8');
+    const secondRun = await placeUnitFile(f.activeSource, f.activeDir, 'unit-under-test.service');
+    const second = await readFile(join(f.activeDir, 'unit-under-test.service'), 'utf8');
+    expect(secondRun.unlinkedDestinationSymlink).toBe(false);
+    expect(second).toBe(first);
+  });
+});
+
+describe('resolveLeaseBrokerSocketForPreflight (#1292 preflight resolution)', () => {
+  it('explicit MOSAIC_LEASE_BROKER_SOCKET wins', () => {
+    expect(
+      resolveLeaseBrokerSocketForPreflight({ MOSAIC_LEASE_BROKER_SOCKET: '/custom/sock' }, 1000),
+    ).toBe('/custom/sock');
+  });
+  it('XDG_RUNTIME_DIR next', () => {
+    expect(resolveLeaseBrokerSocketForPreflight({ XDG_RUNTIME_DIR: '/run/user/1001' }, 1000)).toBe(
+      '/run/user/1001/mosaic-lease/broker.sock',
+    );
+  });
+  it('falls back to /run/user/<uid>', () => {
+    expect(resolveLeaseBrokerSocketForPreflight({}, 1002)).toBe(
+      '/run/user/1002/mosaic-lease/broker.sock',
+    );
+  });
+});

packages/mosaic/src/commands/fleet.spec.ts

@@ -835,13 +835,25 @@ describe('fleet command construction', () => {
     };
     const program = new Command();
     program.exitOverride();
-    registerFleetCommand(program, { runner, mosaicHome: home });
+    // #1292: inject a present broker socket so the preflight passes and this
+    // spec keeps testing its ORIGINAL property (holder-before-agent ordering).
+    // The preflight's own refusal behavior has dedicated specs below.
+    registerFleetCommand(program, {
+      runner,
+      mosaicHome: home,
+      checkBrokerSocket: async () => true,
+    });
 
     try {
       await program.parseAsync(['node', 'mosaic', 'fleet', 'start']);
       await program.parseAsync(['node', 'mosaic', 'fleet', 'stop']);
 
       expect(calls).toEqual([
+        // #1292: fleet start enables + starts the broker FIRST (enable is
+        // idempotent; the unit exists after install), re-checking the socket
+        // before any holder/agent lifecycle effect.
+        ['systemctl', '--user', 'enable', 'mosaic-lease-broker.service'],
+        ['systemctl', '--user', 'start', 'mosaic-lease-broker.service'],
         ['systemctl', '--user', 'start', 'mosaic-tmux-holder.service'],
         ['systemctl', '--user', 'start', '[email protected]'],
         ['systemctl', '--user', 'stop', '[email protected]'],
@@ -852,6 +864,92 @@ describe('fleet command construction', () => {
     }
   });
 
+  it('fleet start refuses with a named error when the broker socket does not appear (#1292)', async () => {
+    const home = await tempDir();
+    const rosterPath = join(home, 'fleet', 'roster.yaml');
+    await mkdir(join(home, 'fleet'), { recursive: true });
+    await writeFile(
+      rosterPath,
+      ['version: 1', 'transport: tmux', 'agents:', '  - name: coder0', '    runtime: codex'].join(
+        '\n',
+      ),
+    );
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+    const program = new Command();
+    program.exitOverride();
+    const errors: string[] = [];
+    const origError = console.error;
+    console.error = (...args: unknown[]) => {
+      errors.push(args.join(' '));
+    };
+    registerFleetCommand(program, {
+      runner,
+      mosaicHome: home,
+      checkBrokerSocket: async () => false,
+    });
+    try {
+      await program.parseAsync(['node', 'mosaic', 'fleet', 'start']);
+      // Refused: no holder/agent starts were issued after the broker attempt.
+      expect(calls).toEqual([
+        ['systemctl', '--user', 'enable', 'mosaic-lease-broker.service'],
+        ['systemctl', '--user', 'start', 'mosaic-lease-broker.service'],
+      ]);
+      expect(errors.join('\n')).toContain('broker-absent');
+      expect(errors.join('\n')).toContain('mosaic fleet install');
+    } finally {
+      console.error = origError;
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
+  it('fleet start re-probes the broker on the SECOND invocation — no ActiveState trust (#1292 sticky half)', async () => {
+    const home = await tempDir();
+    const rosterPath = join(home, 'fleet', 'roster.yaml');
+    await mkdir(join(home, 'fleet'), { recursive: true });
+    await writeFile(
+      rosterPath,
+      ['version: 1', 'transport: tmux', 'agents:', '  - name: coder0', '    runtime: codex'].join(
+        '\n',
+      ),
+    );
+    const calls: string[][] = [];
+    const runner: CommandRunner = async (command, args) => {
+      calls.push([command, ...args]);
+      return { stdout: '', stderr: '', exitCode: 0 };
+    };
+    const program = new Command();
+    program.exitOverride();
+    // Broker socket NEVER appears — the second start must refuse exactly like
+    // the first; RemainAfterExit-style stale unit state changes nothing
+    // because the check is the socket, not systemctl.
+    registerFleetCommand(program, {
+      runner,
+      mosaicHome: home,
+      checkBrokerSocket: async () => false,
+    });
+    const errors: string[] = [];
+    const origError = console.error;
+    console.error = (...args: unknown[]) => {
+      errors.push(args.join(' '));
+    };
+    try {
+      await program.parseAsync(['node', 'mosaic', 'fleet', 'start']);
+      await program.parseAsync(['node', 'mosaic', 'fleet', 'start']);
+      // Two invocations, each refusing after its own broker attempt:
+      expect(
+        calls.filter((c) => c.join(' ') === 'systemctl --user start [email protected]'),
+      ).toHaveLength(0);
+      expect(errors.filter((e) => e.includes('broker-absent')).length).toBeGreaterThanOrEqual(2);
+    } finally {
+      console.error = origError;
+      await rm(home, { recursive: true, force: true });
+    }
+  });
+
   it('waits for an in-flight restart to clear before relaunching (re-entry guard)', async () => {
     const home = await tempDir();
     const rosterPath = join(home, 'fleet', 'roster.yaml');
@@ -2065,8 +2163,19 @@ describe('fleet install — auto-enable units for boot-survival', () => {
 
     await enableFleetUnits(runner, minimalRoster, {});
 
+    expect(calls).toContainEqual(['systemctl', '--user', 'enable', 'mosaic-lease-broker.service']);
     expect(calls).toContainEqual(['systemctl', '--user', 'enable', 'mosaic-tmux-holder.service']);
     expect(calls).toContainEqual(['systemctl', '--user', 'enable', '[email protected]']);
+    // The broker must be enabled BEFORE the holder and agents: a start of any
+    // gated runtime without the broker is exactly the #1292 4-second death.
+    const brokerIndex = calls.findIndex(
+      (c) => c.join(' ') === 'systemctl --user enable mosaic-lease-broker.service',
+    );
+    const holderIndex = calls.findIndex(
+      (c) => c.join(' ') === 'systemctl --user enable mosaic-tmux-holder.service',
+    );
+    expect(brokerIndex).toBeGreaterThanOrEqual(0);
+    expect(brokerIndex).toBeLessThan(holderIndex);
   });
 
   it('install still succeeds when systemctl enable returns non-zero (non-fatal)', async () => {

packages/mosaic/src/commands/fleet.ts

@@ -3,9 +3,11 @@ import {
   access,
   chmod,
   copyFile,
+  lstat,
   mkdir,
   open,
   readFile,
+  readlink,
   stat,
   unlink,
   writeFile,
@@ -89,6 +91,8 @@ export type SleepFn = (ms: number) => Promise<void>;
 
 export interface FleetCommandDeps {
   runner?: CommandRunner;
+  /** Test seam for the #1292 fleet-start broker preflight (socket presence). */
+  checkBrokerSocket?: (path: string) => Promise<boolean> | boolean;
   /** Injectable interactive runner for commands needing inherited TTY (e.g., `tmux attach`). */
   interactiveRunner?: InteractiveRunner;
   /**
@@ -797,6 +801,96 @@ export function buildSystemdEnableCommand(unit: string): string[] {
   return ['systemctl', '--user', 'enable', unit];
 }
 
+/**
+ * Place a unit file into the ACTIVE systemd user directory, never through a
+ * symlink (#1292, measured 2026-08-17).
+ *
+ * ⚠ SET-INDEPENDENCE (fomo-lin, 2026-08-17): the set of unit names carrying
+ * by-path residue and the set of unit names this install copies are
+ * INDEPENDENT. Until 0.0.50 they were disjoint only by accident of which
+ * units the install happened to name — fomo-lin survived copy-through solely
+ * because its one by-path symlink (the broker) was the one unit the install
+ * did NOT copy. Adding the broker to the copy set made the intersection
+ * non-empty on the first run. Whoever adds a fifth unit to the placement
+ * list inherits this helper and its unlink step; do not place units with a
+ * bare copyFile.
+ *
+ * A host provisioned by the enable-by-path convention carries a symlink AT
+ * the unit-name path in ~/.config/systemd/user/ pointing at the shipped
+ * template under ~/.config/mosaic/systemd/user/. Node's copyFile FOLLOWS
+ * that link and overwrites the SEED template instead of placing the active
+ * unit (verified with fs.copyFile on a throwaway systemd user instance) —
+ * silent, rc=0, and it mutates the directory every later reseed reads from.
+ * The same measurement showed `systemctl enable <name>` does NOT rewrite an
+ * existing by-path wants-symlink, so reconciliation must be explicit.
+ *
+ * Placement therefore: if the destination is a symlink, unlink it first
+ * (unlink → copy — copy-then-unlink would mutate the seed and then destroy
+ * the evidence that it did); then copy. Also removes a stale
+ * `default.target.wants/<name>` symlink that points outside the active
+ * directory (readlink — NOT readFile, which follows the link and returns the
+ * target's CONTENT), so the subsequent enable-by-name recreates it against
+ * the active copy. Idempotent: on a clean or already-reconciled destination
+ * every step is a no-op (the copy rewrites identical bytes).
+ *
+ * Returns what was done, for assertions and install reporting.
+ */
+export interface PlaceUnitResult {
+  readonly unit: string;
+  readonly destination: string;
+  /** A symlink at the unit-name path was unlinked (by-path residue). */
+  readonly unlinkedDestinationSymlink: boolean;
+  /** A stale wants-symlink pointing outside the active dir was removed. */
+  readonly removedStaleWantsSymlink: boolean;
+}
+
+export async function placeUnitFile(
+  source: string,
+  systemdUserDir: string,
+  unit: string,
+): Promise<PlaceUnitResult> {
+  const destination = join(systemdUserDir, unit);
+  let unlinkedDestinationSymlink = false;
+  try {
+    const destInfo = await lstat(destination);
+    if (destInfo.isSymbolicLink()) {
+      await unlink(destination);
+      unlinkedDestinationSymlink = true;
+    }
+  } catch {
+    // absent destination — nothing to unlink
+  }
+  await copyFile(source, destination);
+
+  let removedStaleWantsSymlink = false;
+  const wantsLink = join(systemdUserDir, 'default.target.wants', unit);
+  try {
+    const wantsInfo = await lstat(wantsLink);
+    if (wantsInfo.isSymbolicLink()) {
+      // readlink — NOT readFile: readFile FOLLOWS the link and returns the
+      // target file's CONTENT, which is not the question being asked.
+      let target: string | undefined;
+      try {
+        target = await readlink(wantsLink);
+      } catch {
+        target = undefined;
+      }
+      // Normalize (systemctl writes absolute targets; a relative one resolves
+      // against the wants dir). A wants-symlink pointing anywhere other than
+      // the active copy (the by-path convention points at the seed template)
+      // survives enable-by-name unchanged — remove it so enable recreates it.
+      if (target !== undefined && resolve(dirname(wantsLink), target) !== destination) {
+        await unlink(wantsLink);
+        removedStaleWantsSymlink = true;
+      }
+    }
+  } catch {
+    // absent wants link — nothing to reconcile
+  }
+
+  return { unit, destination, unlinkedDestinationSymlink, removedStaleWantsSymlink };
+}
+
 /**
  * Returns the systemctl --user disable command for a given unit.
  * Used by `fleet remove` so a removed agent's enabled unit cannot resurrect on
@@ -831,6 +925,22 @@ export async function enableFleetUnits(
     let succeeded = 0;
     let failed = 0;
 
+    // The lease broker ships with the fleet and every gated runtime needs it
+    // (#1292): seats die at lease registration without it, and no documented
+    // path ever enabled it. Enabled first — alongside the holder — and the
+    // unit must have been placed by installFleet's placeUnitFile step.
+    const brokerResult = await runner(
+      ...splitCommand(buildSystemdEnableCommand('mosaic-lease-broker.service')),
+    );
+    if (brokerResult.exitCode === 0) {
+      succeeded++;
+    } else {
+      failed++;
+      process.stderr.write(
+        `Warning: could not enable mosaic-lease-broker.service: ${brokerResult.stderr || brokerResult.stdout || 'non-zero exit'}\n`,
+      );
+    }
+
     const holderResult = await runner(
       ...splitCommand(buildSystemdEnableCommand('mosaic-tmux-holder.service')),
     );
@@ -1527,7 +1637,7 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
     .description('Install local fleet tools and user systemd units')
     .option('--no-enable', 'Skip enabling units for boot-survival')
     .action(async (opts: { enable?: boolean }) => {
-      await installFleet(cmd, frameworkRoot);
+      await installFleet(cmd, frameworkRoot, runner);
       // Unit enablement needs agent names only, so it reads either version.
       const roster = await loadRosterReadModel(cmd);
       await enableFleetUnits(runner, roster, opts);
@@ -1538,7 +1648,7 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
     .description('Install local fleet tools and user systemd units')
     .option('--no-enable', 'Skip enabling units for boot-survival')
     .action(async (opts: { enable?: boolean }) => {
-      await installFleet(cmd, frameworkRoot);
+      await installFleet(cmd, frameworkRoot, runner);
       // Unit enablement needs agent names only, so it reads either version.
       const roster = await loadRosterReadModel(cmd);
       await enableFleetUnits(runner, roster, opts);
@@ -1591,6 +1701,37 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
             );
             return;
           }
+          if (action === 'start') {
+            // Broker preflight (#1292), re-probed on EVERY invocation: a
+            // gated runtime started without a live lease broker dies ~4s in
+            // while the unit reports active (RemainAfterExit) — enabling +
+            // starting here and then RE-CHECKING the socket refuses loudly
+            // instead of reporting rc0 over a doomed start. This is the
+            // second-start check as much as the first: it never trusts unit
+            // ActiveState.
+            await runChecked(runner, [
+              'systemctl',
+              '--user',
+              'enable',
+              'mosaic-lease-broker.service',
+            ]);
+            await runChecked(runner, [
+              'systemctl',
+              '--user',
+              'start',
+              'mosaic-lease-broker.service',
+            ]);
+            if (!(await brokerSocketPresent(deps))) {
+              console.error(
+                '[fleet] broker-absent: lease broker socket did not appear after enable+start (#1292).',
+              );
+              console.error(
+                '[fleet] remedy: mosaic fleet install (it reconciles either enable convention)',
+              );
+              process.exitCode = 1;
+              return;
+            }
+          }
           if (action === 'restart') {
             // Serialize the holder+agents teardown/relaunch behind the restart lock
             // so a re-entrant restart waits for clean shutdown before relaunching,
@@ -2349,7 +2490,11 @@ export function registerFleetAgentCommands(
     });
 }
 
-async function installFleet(cmd: Command, frameworkRoot: string): Promise<void> {
+async function installFleet(
+  cmd: Command,
+  frameworkRoot: string,
+  runner: CommandRunner,
+): Promise<void> {
   const activePaths = resolveFleetPaths(cmd.opts<{ mosaicHome: string }>().mosaicHome);
   assertDefaultMosaicHomeForSystemd(activePaths.mosaicHome);
   // Read model first: every file this function places is roster-independent, and
@@ -2401,18 +2546,40 @@ async function installFleet(cmd: Command, frameworkRoot: string): Promise<void>
   for (const toolPath of executableToolPaths) {
     await chmod(toolPath, 0o755);
   }
-  await copyFile(
-    join(frameworkRoot, 'systemd', 'user', 'mosaic-tmux-holder.service'),
-    join(activePaths.systemdUserDir, 'mosaic-tmux-holder.service'),
+  // Unit placement (#1292): every unit goes through placeUnitFile — never a
+  // bare copyFile — so a by-path-enable symlink at the destination is
+  // unlinked rather than written through (copy-through would silently
+  // overwrite the SEED template, measured 2026-08-17). The lease broker unit
+  // is placed here too: previously the install named three units and omitted
+  // the broker entirely, which is why no documented path ever enabled it.
+  const placedUnits = await Promise.all(
+    [
+      'mosaic-tmux-holder.service',
+      '[email protected]',
+      '[email protected]',
+      'mosaic-lease-broker.service',
+    ].map((unit) =>
+      placeUnitFile(join(frameworkRoot, 'systemd', 'user', unit), activePaths.systemdUserDir, unit),
+    ),
   );
-  await copyFile(
-    join(frameworkRoot, 'systemd', 'user', '[email protected]'),
-    join(activePaths.systemdUserDir, '[email protected]'),
-  );
-  await copyFile(
-    join(frameworkRoot, 'systemd', 'user', '[email protected]'),
-    join(activePaths.systemdUserDir, '[email protected]'),
+  const reconciled = placedUnits.filter(
+    (result) => result.unlinkedDestinationSymlink || result.removedStaleWantsSymlink,
   );
+  if (reconciled.length > 0) {
+    console.log(
+      `Reconciled ${reconciled.length} unit placement(s) from by-path enable residue: ${reconciled.map((r) => r.unit).join(', ')}`,
+    );
+  }
+  // systemd will not see a replaced unit file without a reload; do it once
+  // after all placements, before any enable call below. runCommand never
+  // rejects (it resolves exitCode 127 on spawn error), so a plain await with
+  // an exitCode check matches the rest of this file's systemctl handling.
+  const reloadResult = await runner(...splitCommand(['systemctl', '--user', 'daemon-reload']));
+  if (reloadResult.exitCode !== 0) {
+    process.stderr.write(
+      `Warning: systemctl --user daemon-reload after unit placement failed (non-systemd host?): ${reloadResult.stderr || reloadResult.stdout || 'non-zero exit'}\n`,
+    );
+  }
 
   // On roster v2 the reconciler owns the generated env: `apply` writes it and
   // `regen` rebuilds it, both from projectRosterV2AgentGeneratedEnv. Writing it
@@ -2609,6 +2776,40 @@ function splitCommand(command: string[]): [string, string[]] {
   return [bin, args];
 }
 
+/**
+ * Lease-broker socket presence for the fleet-start preflight (#1292).
+ * Resolution precedence matches launch.ts's defaultLeaseBrokerSocket and
+ * start-agent-session.sh's broker_socket_path: explicit
+ * MOSAIC_LEASE_BROKER_SOCKET, else $XDG_RUNTIME_DIR/mosaic-lease/broker.sock,
+ * else /run/user/<uid>/mosaic-lease/broker.sock. Pure filesystem check — this
+ * deliberately does NOT consult systemd state: a unit can be active
+ * (RemainAfterExit) with no live socket, and the socket is the thing the
+ * gated runtime connects to. Injectable via deps for tests.
+ */
+export function resolveLeaseBrokerSocketForPreflight(
+  env: NodeJS.ProcessEnv = process.env,
+  uid: number = typeof process.getuid === 'function' ? process.getuid() : 0,
+): string {
+  if (env['MOSAIC_LEASE_BROKER_SOCKET']) return env['MOSAIC_LEASE_BROKER_SOCKET'];
+  const runtimeDir = env['XDG_RUNTIME_DIR'] ?? `/run/user/${uid}`;
+  return join(runtimeDir, 'mosaic-lease', 'broker.sock');
+}
+
+async function brokerSocketPresent(
+  deps: FleetCommandDeps,
+  env: NodeJS.ProcessEnv = process.env,
+): Promise<boolean> {
+  const check = deps.checkBrokerSocket;
+  if (check) return check(resolveLeaseBrokerSocketForPreflight(env));
+  try {
+    const socketPath = resolveLeaseBrokerSocketForPreflight(env);
+    await access(socketPath, constants.S_IFSOCK);
+    return true;
+  } catch {
+    return false;
+  }
+}
+
 /** All supported fleet profile names. */
 export type FleetProfile =
   | 'general'

packages/mosaic/src/commands/lease-doctor-check.ts

@@ -205,6 +205,12 @@ export async function runLeaseEnforcementDoctorCheck(
     message:
       `Lease-enforcement hooks (${matchedMarkers.join(', ')}) are wired in ~/.claude/settings.json, but ${reasons.join(' and ')}. ` +
       'Every gated tool call will fail closed and BRICK this agent (see #869). ' +
-      'Remediate by activating the lease-broker supervisor (systemd unit + socket) or by removing the enforcement hooks from ~/.claude/settings.json.',
+      // #1292: one remedy, correct under BOTH enable conventions (by-path on
+      // the seed template, and copy-then-enable in the active dir). Written
+      // from the 2026-08-17 symlink measurement: `systemctl enable` by name
+      // does NOT rewrite an existing by-path wants-symlink, so teaching a
+      // manual systemctl line here could leave a host with two competing
+      // wants links. fleet install reconciles either shape.
+      'Remedy: run `mosaic fleet install` (it reconciles either enable convention), or remove the enforcement hooks from ~/.claude/settings.json.',
   };
 }

packages/mosaic/src/fleet/fleet-reconciler.acceptance.spec.ts

@@ -459,6 +459,7 @@ describe('FCM-M3-002 reconciler lifecycle acceptance', (): void => {
       plan: {
         generation: 7,
         holder: 'owned',
+        broker: { unitInstalled: false, socketPresent: false },
         agents: [
           {
             name: 'coder0',

packages/mosaic/src/fleet/fleet-reconciler.spec.ts

@@ -92,6 +92,112 @@ async function run(command: FleetReconcileCommand, overrides: Partial<FleetRecon
 }
 
 describe('fleet roster-owned reconciler', (): void => {
+  // ── #1292: broker as first-class plan member + broker-first start ordering ──
+
+  it('reports broker unit and socket state in the plan (socket is the signal, not unit state)', async (): Promise<void> => {
+    const result = await run('status', {
+      statPath: async () => true,
+      checkBrokerSocket: async () => true,
+    });
+    expect(result.plan.broker).toEqual({ unitInstalled: true, socketPresent: true });
+  });
+
+  it('reports a dead broker as socketPresent=false even when the unit is installed (enabled-but-dead is the #1292 shape)', async (): Promise<void> => {
+    const result = await run('status', {
+      statPath: async () => true,
+      checkBrokerSocket: async () => false,
+    });
+    expect(result.plan.broker).toEqual({ unitInstalled: true, socketPresent: false });
+  });
+
+  it('reports broker-absent when neither seam is present (defaults false, never guesses healthy)', async (): Promise<void> => {
+    const result = await run('status');
+    expect(result.plan.broker).toEqual({ unitInstalled: false, socketPresent: false });
+  });
+
+  it('command start enables and starts the broker BEFORE the holder and any agent unit', async (): Promise<void> => {
+    const calls: string[][] = [];
+    const result = await run('start', {
+      runner: async (command, args) => {
+        calls.push([command, ...args]);
+        if (command === 'tmux' && args.includes('list-sessions')) {
+          return { stdout: '_holder\ncoder0\n', stderr: '', exitCode: 0 };
+        }
+        if (command === 'tmux' && args.includes('show-environment')) {
+          return {
+            stdout:
+              'HOME=/home/mosaic\nMOSAIC_FLEET_OWNER=11111111-1111-4111-8111-111111111111\nMOSAIC_TMUX_HOLDER=_holder\nMOSAIC_TMUX_SOCKET=mosaic-fleet\nPATH=/usr/bin:/bin\nPWD=/home/mosaic\n',
+            stderr: '',
+            exitCode: 0,
+          };
+        }
+        return { stdout: '', stderr: '', exitCode: 0 };
+      },
+    });
+    expect(result.lifecycle).toBe('complete');
+    const brokerEnable = calls.findIndex(
+      (c) => c.join(' ') === 'systemctl --user enable mosaic-lease-broker.service',
+    );
+    const brokerStart = calls.findIndex(
+      (c) => c.join(' ') === 'systemctl --user start mosaic-lease-broker.service',
+    );
+    const holderStart = calls.findIndex(
+      (c) => c.join(' ') === 'systemctl --user start mosaic-tmux-holder.service',
+    );
+    const agentStart = calls.findIndex(
+      (c) => c.join(' ') === 'systemctl --user start [email protected]',
+    );
+    expect(brokerEnable).toBeGreaterThanOrEqual(0);
+    expect(brokerStart).toBeGreaterThan(brokerEnable);
+    // Holder start may be absent (holder 'owned' in this fixture); if present it must follow the broker.
+    if (holderStart >= 0) expect(holderStart).toBeGreaterThan(brokerStart);
+    expect(agentStart).toBeGreaterThan(brokerStart);
+  });
+
+  it('apply with a running desired agent also enables and starts the broker first', async (): Promise<void> => {
+    const calls: string[][] = [];
+    const runningRoster: FleetRosterV2 = {
+      ...roster,
+      agents: roster.agents.map((agent) =>
+        agent.name === 'coder0'
+          ? { ...agent, lifecycle: { enabled: true, desiredState: 'running' as const } }
+          : agent,
+      ),
+    };
+    const result = await executeFleetReconcile({
+      roster: runningRoster,
+      command: 'apply',
+      expectedGeneration: 7,
+      deps: deps({
+        readRoster: async () => runningRoster,
+        runner: async (command, args) => {
+          calls.push([command, ...args]);
+          if (command === 'tmux' && args.includes('list-sessions')) {
+            return { stdout: '_holder\n', stderr: '', exitCode: 0 };
+          }
+          if (command === 'tmux' && args.includes('show-environment')) {
+            return {
+              stdout:
+                'HOME=/home/mosaic\nMOSAIC_FLEET_OWNER=11111111-1111-4111-8111-111111111111\nMOSAIC_TMUX_HOLDER=_holder\nMOSAIC_TMUX_SOCKET=mosaic-fleet\nPATH=/usr/bin:/bin\nPWD=/home/mosaic\n',
+              stderr: '',
+              exitCode: 0,
+            };
+          }
+          return { stdout: '', stderr: '', exitCode: 0 };
+        },
+      }),
+    });
+    expect(result.applied).toBe(true);
+    const brokerStart = calls.findIndex(
+      (c) => c.join(' ') === 'systemctl --user start mosaic-lease-broker.service',
+    );
+    const agentStart = calls.findIndex(
+      (c) => c.join(' ') === 'systemctl --user start [email protected]',
+    );
+    expect(brokerStart).toBeGreaterThanOrEqual(0);
+    expect(agentStart).toBeGreaterThan(brokerStart);
+  });
+
   it('fails closed on a symlinked fleet ancestor without touching its target', async (): Promise<void> => {
     const home = await lockHome();
     const fleet = join(home, 'fleet');

packages/mosaic/src/fleet/fleet-reconciler.ts

@@ -43,6 +43,10 @@ export interface FleetReconcileDeps {
   readonly overrideDir?: string;
   readonly homeDirectory?: string;
   readonly readHolderIdentity?: () => Promise<string>;
+  /** Test/observation seams for the lease-broker plan member (#1292). */
+  readonly statPath?: (path: string) => Promise<boolean> | boolean;
+  readonly checkBrokerSocket?: (path: string) => Promise<boolean> | boolean;
+  readonly brokerSocketEnv?: NodeJS.ProcessEnv;
   readonly validateRoster?: (roster: FleetRosterV2) => Promise<void>;
   readonly prepareProjections?: (roster: FleetRosterV2) => Promise<readonly unknown[]>;
   readonly applyProjection?: (prepared: unknown) => Promise<unknown>;
@@ -74,6 +78,17 @@ export interface FleetReconcileObservedAgent {
 export interface FleetReconcilePlan {
   readonly generation: number;
   readonly holder: 'owned' | 'missing' | 'ownership-mismatch';
+  /**
+   * Lease broker observation (#1292): every gated runtime registers with the
+   * broker or dies ~4s in — a broker not in the plan cannot be reported as
+   * drifted, which made "broker died an hour ago" and "broker fine"
+   * produce identical output. `unitInstalled` = unit file present in the
+   * active dir; `socketPresent` = live broker at the resolved socket path.
+   */
+  readonly broker: {
+    readonly unitInstalled: boolean;
+    readonly socketPresent: boolean;
+  };
   readonly agents: readonly FleetReconcileObservedAgent[];
   readonly unmanagedSessions: readonly string[];
 }
@@ -314,6 +329,39 @@ function isObservational(command: FleetReconcileCommand): boolean {
   return command === 'plan' || command === 'status' || command === 'verify' || command === 'doctor';
 }
 
+/**
+ * Observe the lease broker for the plan (#1292). Unit presence via systemctl
+ * is-system-running is NOT the signal — a unit can be enabled-but-dead. The
+ * authoritative signal is the socket the gated runtimes connect to, matching
+ * broker-supervisor.ts's `checkBrokerSupervisorHealth` (healthy ===
+ * socketPresent). Injectable so tests drive every branch without a broker.
+ */
+async function observeBroker(deps: FleetReconcileDeps): Promise<FleetReconcilePlan['broker']> {
+  const homeDirectory = deps.homeDirectory ?? homedir();
+  const env = (deps.brokerSocketEnv ?? process.env) as NodeJS.ProcessEnv;
+  const uid = typeof process.getuid === 'function' ? process.getuid() : 0;
+  const runtimeDir = env['XDG_RUNTIME_DIR'] ?? `/run/user/${uid}`;
+  const socketPath =
+    env['MOSAIC_LEASE_BROKER_SOCKET'] ?? join(runtimeDir, 'mosaic-lease', 'broker.sock');
+  const configHome = env['XDG_CONFIG_HOME'] ?? join(homeDirectory, '.config');
+  const unitPath = join(configHome, 'systemd', 'user', 'mosaic-lease-broker.service');
+  const statPath = deps.statPath;
+  const checkBrokerSocket = deps.checkBrokerSocket;
+  let unitInstalled = false;
+  let socketPresent = false;
+  try {
+    unitInstalled = statPath ? await statPath(unitPath) : false;
+  } catch {
+    unitInstalled = false;
+  }
+  try {
+    socketPresent = checkBrokerSocket ? await checkBrokerSocket(socketPath) : false;
+  } catch {
+    socketPresent = false;
+  }
+  return { unitInstalled, socketPresent };
+}
+
 async function observeFleet(
   roster: FleetRosterV2,
   deps: FleetReconcileDeps,
@@ -324,10 +372,12 @@ async function observeFleet(
     '-F',
     '#{session_name}',
   ]);
+  const broker = await observeBroker(deps);
   if (sessionsResult.exitCode !== 0) {
     return {
       generation: roster.generation,
       holder: 'missing',
+      broker,
       agents: await observeAgents(roster, deps, new Set<string>()),
       unmanagedSessions: [],
     };
@@ -350,6 +400,7 @@ async function observeFleet(
   return {
     generation: roster.generation,
     holder,
+    broker,
     agents: await observeAgents(roster, deps, sessions),
     unmanagedSessions: Object.freeze(unmanagedSessions.sort()),
   };
@@ -517,6 +568,24 @@ async function executeExplicitLifecycle(
     }
   }
   try {
+    // Broker FIRST (#1292): a gated runtime started without a running lease
+    // broker dies ~4 seconds in at registration — enable the unit (install
+    // places it) and start it before any holder/agent lifecycle effect. The
+    // socket re-check after start is the same probe observeBroker uses, so a
+    // unit that starts but never produces a socket is caught here, not four
+    // seconds later inside a doomed seat.
+    if (request.command === 'start') {
+      await runChecked(request.deps, 'systemctl', [
+        '--user',
+        'enable',
+        'mosaic-lease-broker.service',
+      ]);
+      await runChecked(request.deps, 'systemctl', [
+        '--user',
+        'start',
+        'mosaic-lease-broker.service',
+      ]);
+    }
     if (request.command === 'start' && plan.holder === 'missing') {
       await runChecked(request.deps, 'systemctl', [
         '--user',
@@ -562,6 +631,12 @@ async function applyDesiredLifecycle(
     (agent: FleetRosterV2Agent): boolean =>
       agent.lifecycle.enabled && agent.lifecycle.desiredState === 'running',
   );
+  // Broker before any running agent, same ordering and reason as the
+  // command-driven path above (#1292).
+  if (needsRunningAgent) {
+    await runChecked(deps, 'systemctl', ['--user', 'enable', 'mosaic-lease-broker.service']);
+    await runChecked(deps, 'systemctl', ['--user', 'start', 'mosaic-lease-broker.service']);
+  }
   if (needsRunningAgent && plan.holder === 'missing') {
     await runChecked(deps, 'systemctl', ['--user', 'start', 'mosaic-tmux-holder.service']);
   }