docs(ri-050): RI-2-001 independent review recorded — APPROVED (#1275)

Review 172 on PR #1278 (head 99b8f6ea): forge suite 116/116 executed at
head, workspace typecheck 45/45, consumer sweep clean, digest gate
before==after. CI red on the PR is the lane-wide fleet-test failure only
and carries no information about the change (fred, log-content analysis).
Continuation by fargo (sb-it-1-dt) per Jason; identity incident and fred's
ruling recorded in the scratchpad. Wave 2 (RI-2-002 + RI-4-001) next.

docs/PRD.md

@@ -1368,3 +1368,38 @@ All work is **alpha** (< 0.1.0) until Jason approves 0.1.0 beta release.
 10. ASSUMPTION: **Conversations and messages get their own PG tables** (not stored in brain's entity model). They follow a chat-specific schema with proper foreign keys to users and projects. Rationale: Chat has different access patterns (streaming, pagination, search) than brain entities.
 
 11. RESOLVED: **Pi handles all target LLM providers natively.** Anthropic, OpenAI/Codex, Z.ai, Ollama, LM Studio, and llama.cpp are all supported via Pi's built-in providers or `models.json` configuration with `openai-completions` API type. No custom provider adapters needed in @mosaicstack/agent — only configuration management.
+
+---
+
+## Release Integrity Workstream (RI, #1275)
+
+### Problem and objective
+
+At `next` 476db12b (review of 2026-08-17), publication from `next` is not bound to the full verification pipeline for the same commit: the publish pipeline's publish steps depend on `build` only, while ordinary push CI excludes `next`. Public Forge/MACP paths contain false-success placeholders: a stub executor that reports `completed` with exit zero, planning/remediation gates that execute literal `true`, a review gate that echoes an approving verdict, and a gate runner that treats empty commands and unimplemented CI-provider gates as passing. Shipping UI surfaces can render a failed fetch as an empty, healthy collection.
+
+Objective: for alpha 0.0.50, the release cannot publish, report, or display work state that the repository has not actually verified. Decisions SDLC-D-033 through SDLC-D-038 (Jason, 2026-08-17) scope this floor; full decision text and required-behavior lists live in jarvis-brain `docs/plans/2026-08-16_mosaic-stack-sdlc-protocol.md` and `data/decisions/mosaic-stack-sdlc-protocol.json`. This section restates only the normative requirements.
+
+### Normative requirements
+
+1. **RI-N1 Exact-commit publication verification (SDLC-D-034).** One canonical terminal verification command performs self-contained re-verification in the publish pipeline against the job's checked-out commit before any external publication effect. The command contains or invokes the complete mandatory verification set (semantic parity with the PR merge gate, including sanitization, upgrade-guard, typecheck, lint, format check, tests, and build); CI and publication do not maintain separate semantic checklists. Every publish step depends on the verification step in the executable pipeline DAG. Provider commit identity and `git rev-parse HEAD` must identify the same commit. Missing, skipped, cancelled, stale, or inconclusive checks fail closed. Documentation-only runs may skip publication but cannot bypass verification when a publication effect will occur. A negative control must prove that a broken check blocks every publish step.
+
+2. **RI-N2 Fail-closed Forge/MACP with explicit simulation (SDLC-D-035).** Simulation requires explicit caller intent (e.g. `--simulate`) and produces a distinct typed `simulated` state that can never satisfy dependencies, acceptance criteria, gates, merge, or release. Normal execution exits nonzero with a typed capability failure when a required executor, reviewer, command, or CI provider is absent — no stub completion, no literal-`true` gates, no synthetic approvals, no empty-command passes. A manual gate with no automation enters a waiting state; it does not pass. Positive tests prove explicit simulation still works; negative controls prove simulation and every missing-provider case cannot advance lifecycle state.
+
+3. **RI-N3 One transitional PRD authority (SDLC-D-036).** `@mosaicstack/prdy` structured storage under `docs/prdy/`, driven by `mosaic mission --plan`, is the authoritative PRD representation for the alpha. `mosaic prdy` either routes through the same application service or operates only as an explicit, named Markdown import/export adapter; `docs/PRD.md` is not a peer authority. `mission --plan` must persist the mission↔PRD linkage (mission id/version, PRD id/version, selected requirements). Markdown output is a generated view carrying source identity; editing it cannot mutate authority silently. Import is explicit, validated, and conflict-aware (proposed successor, never overwrite). Structural validity is separate from approval.
+
+4. **RI-N4 One quality-rails evaluator (SDLC-D-037).** The TypeScript quality-rails package is the sole authoritative evaluator. A complete probe inventory maps every current TypeScript and shell check to one canonical check with disposition (preserve/strengthen/retire, each named). Effective shell enforcement probes are absorbed before their independent paths retire; expected-file presence alone is not parity. The evaluator returns typed results (`passed`/`failed`/`blocked`/`error`/`not-applicable`) with check version, subject, and reason; missing implementation, missing input, unknown check, process error, timeout, or malformed output can never become `passed` or an unqualified skip. Check definitions and policy are versioned and digested. Shell commands become thin adapters with no separate verdict logic. The canonical terminal verification command (RI-N1) invokes this evaluator rather than duplicating its logic. Contract, parity, and negative-control tests are required, plus independent review of probe equivalence.
+
+5. **RI-N5 Consequence-aware stale UI (SDLC-D-038).** Mission Control distinguishes typed freshness states (`current`, `stale`, `partial`, `unknown`, `unavailable`) rather than inferring from empty arrays or null. A failed fetch never renders as an empty healthy collection. Last-known data may display for situational awareness only with source identity, version, and age visibly labeled; any derived completion/assurance/release verdict whose inputs are stale becomes `unknown`; all state-changing actions are disabled until fresh state loads and is revalidated. With no verified snapshot, surfaces show an explicit unavailable state. Cache corruption, cross-workspace data, schema mismatch, and version regression invalidate the snapshot. Tests cover the failure matrix (network, auth, malformed, partial, corruption, stale age, schema mismatch, recovery, stale-action rejection) with negative controls proving no case yields a current green verdict or enabled mutation.
+
+### Acceptance criteria
+
+- AC-RI-1: A push to `next` that fails any mandatory verification step publishes nothing (no npm package, no image), demonstrated by a checked-in negative control and by pipeline evidence on a real `next` publish run where the verification step is green and every publish step depends on it.
+- AC-RI-2: With no executor/reviewer/CI provider wired, Forge and MACP normal runs exit nonzero with typed capability failures; with `--simulate`, runs complete but every result is typed `simulated` and cannot satisfy any gate, dependency, or completion state — proven by unit tests including negative controls.
+- AC-RI-3: A PRD created or revised through either `mosaic mission --plan` or `mosaic prdy` resolves to one authority under `docs/prdy/` with stable identities and versions; the mission↔PRD linkage survives restart; a Markdown export is labeled as generated and cannot silently become a second writer; divergent legacy content blocks baseline claims until explicitly resolved — proven by contract tests.
+- AC-RI-4: `quality-rails check` through any entry point (TS CLI, framework shell adapter) returns the same typed verdict for the same subject; the probe inventory names every legacy check's disposition; a deliberately broken probe fails closed — proven by contract/parity/negative-control tests and independent review of probe equivalence.
+- AC-RI-5: No shipping surface renders a failed fetch as an empty healthy state; stale/partial/unavailable states are typed, labeled, and mutation-disabled — proven by the failure-matrix tests.
+- AC-RI-6: All cards merged to `next` via squash PR with terminal-green CI; release evidence for 0.0.50 records commit, verification run, and published artifacts.
+
+### Out of scope
+
+The canonical dispatcher/control-plane vertical slice (work graph, execution attempts, fenced leases, typed check-in, independent verifier dispatch) is decided post-alpha (SDLC-D-033, option B). Multi-pipeline verification certificates (SDLC-D-034 option B) are post-alpha. Full AF-1..AF-4 objective matrices and Mission Control portfolio surfaces are post-alpha.

docs/release-integrity/TASKS.md

@@ -0,0 +1,42 @@
+# Tasks — Release Integrity Workstream (RI-050, #1275)
+
+> Single-writer: the RI-050 orchestrator (jarvis, dragon-lin) only. Workers read but never modify.
+>
+> **Mission:** alpha 0.0.50 release-integrity floor (decisions SDLC-D-033..038).
+> **PRD:** [docs/PRD.md § Release Integrity Workstream](../PRD.md#release-integrity-workstream-ri-1275)
+> **Issue:** #1275 (remains open until RI-V-001 closes)
+> **Base branch:** `next` (all cards branch from `origin/next`, squash-merge via PR)
+>
+> **Execution note:** the `agent` column uses `pi-glm-5.3` — outside the pipeline-cron model
+> table on purpose. This workstream is executed by jarvis on dragon-lin with local pi workers
+> (`pi --model zai/glm-5.3:high`); pipeline crons must not auto-claim these rows.
+>
+> **Status values:** `not-started` | `in-progress` | `done` | `blocked` | `failed` | `needs-qa`
+> `done` requires: repo quality gates green, independent review recorded, terminal-green CI on
+> the PR head, squash merge to `next`, and acceptance evidence in notes.
+
+| id       | status      | description                                                                                                                                                                                                                                                                      | issue | agent      | repo              | branch                            | depends_on                                                 | estimate | notes                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+| -------- | ----------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----- | ---------- | ----------------- | --------------------------------- | ---------------------------------------------------------- | -------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| RI-0-001 | in-progress | Bootstrap: issue #1275, PRD section, this DAG, scratchpad (docs only)                                                                                                                                                                                                            | #1275 | pi-glm-5.3 | mosaicstack/stack | docs/ri-050-mission-bootstrap     | —                                                          | 6K       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| RI-1-001 | in-progress | RI-N1: canonical terminal verification command + publish-pipeline exact-commit gate (every publish step depends on verify; commit identity check; fail closed)                                                                                                                   | #1275 | pi-glm-5.3 | mosaicstack/stack | feat/ri-050-publish-gate          | RI-0-001                                                   | 25K      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| RI-1-002 | not-started | RI-N1 negative control: checked-in tests proving a broken mandatory check blocks every publish step and that DAG edges cannot be bypassed                                                                                                                                        | #1275 | pi-glm-5.3 | mosaicstack/stack | test/ri-050-publish-gate-negative | RI-1-001                                                   | 12K      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| RI-2-001 | in-progress | RI-N2 (Forge): remove stub-executor false success; `--simulate` typed `simulated` results that satisfy nothing; literal-`true` gates and echo-review replaced with real gates or typed waiting-for-authority                                                                     | #1275 | pi-glm-5.3 | mosaicstack/stack | fix/ri-050-forge-fail-closed      | RI-0-001                                                   | 20K      | Independent review APPROVED 2026-08-17 (Gitea review 172 on PR #1278, head 99b8f6ea; reviewing seat fargo — recorded under shared host principal mos-dt-0, provenance correction posted by fred; wrapper gap filed by fred). Executed at head: forge tests 116/116, lint green, typecheck green after building macp dist (minimal-install artifact, not a defect), workspace typecheck 45/45, no external type consumers of the changed interfaces. CI red = known lane-wide fleet-test failure only, carries no information about this change (fred, log-content analysis, pipelines 2456-2458). Non-blocking finding: README L141-143 + skills/mosaic-forge/SKILL.md document bare forge run/resume, which now fails closed — fast-follow docs touch. Merge queued behind #1270. |
+| RI-2-002 | not-started | RI-N2 (MACP): gate runner fails closed on empty commands, stub executors, and unimplemented CI-provider gates unless explicit simulate; typed capability failures                                                                                                                | #1275 | pi-glm-5.3 | mosaicstack/stack | fix/ri-050-macp-fail-closed       | RI-0-001                                                   | 15K      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| RI-3-001 | not-started | RI-N4: complete probe inventory mapping every TS and shell quality-rail check to one canonical check with disposition (preserve/strengthen/retire, each named)                                                                                                                   | #1275 | pi-glm-5.3 | mosaicstack/stack | docs/ri-050-qr-probe-inventory    | RI-0-001                                                   | 12K      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| RI-3-002 | not-started | RI-N4: TS evaluator absorbs effective shell probes; typed results (passed/failed/blocked/error/not-applicable) with versioned digested check definitions; shell commands become thin adapters; contract/parity/negative-control tests                                            | #1275 | pi-glm-5.3 | mosaicstack/stack | feat/ri-050-qr-evaluator          | RI-3-001                                                   | 30K      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| RI-4-001 | not-started | RI-N3: one PRD application service — `mission --plan` persists mission↔PRD linkage (ids/versions/selected requirements); `mosaic prdy` routes through the service or becomes a named import/export adapter; Markdown is a labeled generated view; explicit conflict-aware import | #1275 | pi-glm-5.3 | mosaicstack/stack | feat/ri-050-prd-authority         | RI-0-001                                                   | 35K      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| RI-5-001 | not-started | RI-N5: typed freshness states (current/stale/partial/unknown/unavailable); no failed-fetch-renders-empty; stale derived verdicts → unknown; mutations disabled when stale; failure-matrix tests                                                                                  | #1275 | pi-glm-5.3 | mosaicstack/stack | feat/ri-050-web-stale-safety      | RI-0-001                                                   | 25K      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| RI-V-001 | not-started | Final verification + release evidence: all cards verified merged, negative controls demonstrated, real `next` publish run green on exact commit, evidence pack recorded                                                                                                          | #1275 | pi-glm-5.3 | mosaicstack/stack | docs/ri-050-release-evidence      | RI-1-002, RI-2-001, RI-2-002, RI-3-002, RI-4-001, RI-5-001 | 10K      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+
+## Dispatch waves (max 2 parallel workers)
+
+1. RI-1-001 + RI-2-001
+2. RI-2-002 + RI-4-001
+3. RI-3-001 + RI-5-001
+4. RI-1-002 + RI-3-002
+5. RI-V-001
+
+## Budget
+
+Derived soft cap: 250K tokens (no explicit cap given). Projected total: 190K.
+Conservative mode (1 worker) above 70% projected; freeze above 90%.

docs/scratchpads/ri-050.md

@@ -0,0 +1,191 @@
+# Scratchpad — RI-050 orchestrator (jarvis, dragon-lin)
+
+Mission: alpha 0.0.50 release-integrity floor. Issue #1275. Base `next` @ 476db12b.
+Design SSOT: jarvis-brain `docs/plans/2026-08-16_mosaic-stack-sdlc-protocol.md` (SDLC-D-033..038).
+
+## Mode (Jason's directives)
+
+- Orchestrator: jarvis (this session, dragon-lin). NOT mos-claude; work stays on this host.
+- Workers: local pi headless — `pi --model zai/glm-5.3:high -p` in the card's worktree, tools read,bash,edit,write.
+- Delegation override of stack AGENTS.md `agent` column: rows carry `pi-glm-5.3` (outside cron table so no auto-claim).
+- Target branch: `next`. Cards branch from `origin/next`, squash-merge via PR.
+
+## Operational constraints (measured this session)
+
+- Main checkout at `/home/jwoltje/src/mosaic-stack` is a dirty diverged `main` (ahead 1139/behind 711) — NEVER touched. All work in `/home/jwoltje/src/mosaic-stack-worktrees/<branch>`.
+- Disk: /home 187G free. /tmp only 8.7G — keep pnpm stores/node_modules under /home.
+- `main` and `next` have DIVERGED; PRs target `next`.
+- Identity: pin `GITEA_LOGIN=mosaicstack-jarvis` for all wrapper ops. Issue #1275 verified authored by @jarvis.
+- `ci-queue-wait.sh` on this host is fail-open (board: fix #1032 not installed) — substitute SHA-status checks via `/commits/{sha}/status` and diff failing step names.
+- CI on PRs runs `pull_request` pipelines (any branch) incl. ci-postgres service. Push CI runs on main only; publish runs on push/tag to next + manual.
+- Wrapper gaps on this host per board (7 gaps; e.g. no pr-review-list, issue-assign broken, pr-merge makes no trailers): verify outcomes by reading back provider state, never trust rc alone.
+- Publish pipeline currently: install → build → publish-npm/publish-next-npm (+image). No verify. CI steps: install, sanitization, upgrade-guard, typecheck, lint, format, test, ci-postgres.
+
+## Budget
+
+Soft cap 250K. Projected 190K across 10 cards. Track per-card used vs estimate in TASKS.md notes.
+
+## Progress log
+
+- 2026-08-16 23:52 — Issue #1275 created (@jarvis verified).
+- 2026-08-16 23:5x — Bootstrap branch `docs/ri-050-mission-bootstrap` from origin/next@476db12b; PRD section + TASKS.md + this scratchpad written. RI-0-001 in-progress.
+
+## Wave 1 dispatched (2026-08-17 00:35)
+
+- RI-1-001 worker: pi glm-5.3:high, pid 2322125, worktree ri-1-001, log /var/tmp/ri-050/ri-1-001-run.log
+- RI-2-001 worker: pi glm-5.3:high, pid 2322126, worktree ri-2-001, log /var/tmp/ri-050/ri-2-001-run.log
+- Gotcha recorded: pi has no -f flag (that's pi-do.sh); pass brief as positional message. First launch died "Unknown option: -f" — relaunched.
+- CI lane: PR #1276 (bootstrap) fails `test` at base like every next PR — fred's green #1270 unblocks (comms sent 2026-08-17T05:21Z, `comms/20260817T052148Z__from-jarvis__650fe8.md`). Merge gate for all RI PRs queues behind #1270.
+- Live RI-N1 evidence posted to #1275 (comment 22915): pipeline 2439 publish-next-npm SUCCESS beside build-gateway FAILURE.
+
+---
+
+# HANDOFF — RI-050 continuation (written 2026-08-17 ~08:45 UTC, jarvis/dragon-lin)
+
+You are taking over the alpha 0.0.50 release-integrity workstream in place. Everything you
+need is on the remote. Read this whole file, then `docs/release-integrity/TASKS.md` (same
+branch), then the PRD section (`docs/PRD.md` § Release Integrity Workstream, same branch).
+
+## Identity / mode
+
+- Orchestrator identity: `jarvis` (dragon-lin). You continue as the RI-050 orchestrator under
+  whatever identity Jason gives you — if you are NOT jarvis, say so in comms and PR bodies.
+- Jason's standing directives for this mission: work happens on THIS repo (mosaicstack/stack),
+  PRs target `next` (NOT main), workers are local pi headless sessions on
+  `zai/glm-5.3:high`. Do not hand this to mos-claude. Do not borrow other seats' lanes.
+- All wrapper ops: pin `GITEA_LOGIN=mosaicstack-jarvis` (issue #1275 was verified authored by
+  @jarvis; keep identity consistent or verify yours with issue-view and READ BACK user.login).
+- CI substitution rule (this host's ci-queue-wait.sh is fail-open; fix #1032 not installed):
+  judge CI by SHA-status via `/api/v1/repos/mosaicstack/stack/commits/{sha}/status` or the
+  woodpecker API (`pipeline-status.sh -r mosaicstack/stack -n N -f json`), and DIFF THE
+  FAILING STEP NAMES rather than trusting rc.
+
+## Mission state at handoff
+
+Mission: alpha 0.0.50 release-integrity floor. Issue #1275 (open, has live-evidence comment).
+Decisions SDLC-D-033..038 live in jarvis-brain
+`docs/plans/2026-08-16_mosaic-stack-sdlc-protocol.md` (normative text also mirrored in the
+PRD section on this branch, so this repo is self-sufficient).
+
+Base: `origin/next` @ 476db12b. NOTE: `main` and `next` have DIVERGED — never base on main.
+
+Branches (all pushed, all clean trees):
+
+- `docs/ri-050-mission-bootstrap` @ 5114faa2 → PR #1276 (open, mergeable) — bootstrap docs +
+  this scratchpad + TASKS.md DAG. STATUS: CI red on `test` only, which is the known lane-wide
+  failure (see blocker below); own prettier issue already fixed.
+- `feat/ri-050-publish-gate` @ 0aa5ed35 → PR #1277 (open, mergeable) — RI-1-001 COMPLETE
+  (worker reported success, orchestrator review PASSED: verify step asserts CI_COMMIT_SHA ==
+  git rev-parse HEAD then runs canonical `pnpm verify:release`; every publish/image step
+  depends_on verify directly, confirmed by parsing the DAG: publish-npm, publish-next-npm,
+  build-gateway/appservice/web all -> [build, verify]; invariant test
+  scripts/verify-release.test.mjs passes 7/7 locally with negative fixtures). CI: same known
+  lane-red `test` step only.
+- `fix/ri-050-forge-fail-closed` @ 99b8f6ea → PR #1278 (open, mergeable) — RI-2-001 worker
+  reported success (typed `FORGE_*` capability errors, --simulate typed simulated everywhere,
+  vacuous true/echo gates replaced, closed ForgeOutcome set, 116 tests green incl. 16 new).
+  ORCHESTRATOR REVIEW NOT YET DONE — your first job. Review the diff
+  (1391 insertions across forge src), check the fail-closed paths and that simulated
+  results cannot satisfy any consumer, run `pnpm --filter @mosaicstack/forge test`.
+
+## The one blocker
+
+Every `next` PR pipeline is red on ONE assertion:
+`packages/mosaic/framework/tools/fleet/test-start-agent-session.sh:103` ("host provides 'pi'
+in the system path"). Pre-existing at base; affects PRs #1276/#1277/#1278 identically.
+fred's PR #1270 ("unblocks every PR on next") is green and open — it is HIS to merge; do not
+merge it yourself. jarvis sent comms (`comms/20260817T052148Z__from-jarvis__650fe8.md` in
+jarvis-brain) asking merge timing; no reply yet as of handoff. Merge gates for ALL RI PRs
+queue behind #1270 landing. Until then: review/develop freely, merge nothing that needs the
+green gate (docs-only #1276 arguably could merge red-lane with Jason's explicit call — ask,
+don't assume).
+
+## Remaining DAG (docs/release-integrity/TASKS.md is canonical)
+
+Wave 2 (next): RI-2-002 MACP fail-closed (brief pattern: mirror RI-2-001 for
+packages/macp/src/gate-runner.ts — empty commands, stub executors, unimplemented CI-provider
+gates fail closed; explicit simulate) and RI-4-001 PRD authority (one PRD service;
+@mosaicstack/prdy docs/prdy authoritative via `mosaic mission --plan`; `mosaic prdy` routes
+or becomes named Markdown adapter; mission<->PRD linkage persists — see PRD RI-N3).
+Wave 3: RI-3-001 probe inventory (docs), RI-5-001 web stale-safety.
+Wave 4: RI-1-002 negative-control tests, RI-3-002 TS evaluator absorbs shell probes.
+Final: RI-V-001 evidence pack (real green next publish run post-gate + all cards verified).
+
+## Worker mechanics (measured, reuse)
+
+- Dispatch: create worktree `git -C /home/jwoltje/src/mosaic-stack worktree add
+/home/jwoltje/src/mosaic-stack-worktrees/<id> -b <branch> origin/next`, write a brief to
+  /var/tmp/ri-050/, then run from INSIDE the worktree:
+  `pi -p --no-session --model zai/glm-5.3:high --tools read,bash,edit,write "$(cat brief.md)"`
+  (pi has NO -f flag — pass the brief as a positional message; first dispatch died on that).
+- Briefs for 1-001/2-001 are at /var/tmp/ri-050/ on dragon-lin (may not survive; the
+  pattern is fully described above and in TASKS.md).
+- Briefs must carry: worktree path, branch, base, requirements, known base-red list (so the
+  worker doesn't chase it), gates to run, PR creation command with GITEA_LOGIN pin, "do NOT
+  merge, do NOT touch docs/TASKS.md", and the JSON report format.
+- Verify worker claims: read the PR, run their tests yourself, parse pipeline step names.
+
+## Do-not-touch
+
+- Main checkout at /home/jwoltje/src/mosaic-stack (dirty diverged main) — never touch.
+- fred's open PRs (#1270 and others) — review evidence welcome, merging his is not yours.
+- Other RI PRs' authors' lanes: #1277/#1278 are yours to gate and merge ONCE lane is green
+  and review is recorded.
+- Never `--no-verify`; never bypass the wrapper-fails-closed rule (wrapper failure ⇒
+  `blocked + report exact command + stop`).
+
+## Session-restore command sequence
+
+1. `git -C /home/jwoltje/src/mosaic-stack-worktrees/ri-050 fetch origin --prune`
+2. Read this file + `docs/release-integrity/TASKS.md` + PRD section.
+3. Check PR states (#1270, #1276, #1277, #1278) and lane CI (SHA-status per above).
+4. Review RI-2-001 (PR #1278) if not yet done; then dispatch wave 2.
+
+— jarvis, 2026-08-17
+
+---
+
+# CONTINUATION — fargo (sb-it-1-dt)
+
+Orchestrator seat is now **fargo** on sb-it-1-dt (Jason, 2026-08-17): Claude seat, worktree discipline
+per fred's ruling (`~/agent-work/<slug>`, create → work → commit → push → remove as one act; the
+helper's `/src` refusal is a web1 convention, does not bind here). fred supports; lane rulings are
+his. Workers remain local pi `zai/glm-5.3:high` + limited Claude per Jason.
+
+## 2026-08-17 — RI-2-001 independent review DONE
+
+- **PR #1278 APPROVED** (Gitea review 172, pinned to head 99b8f6ea). Executed evidence, not read-only:
+  forge suite 116/116 at head (matches PR claim), forge lint green, forge typecheck green after
+  building `@mosaicstack/macp` dist (TS2307 on bare `pnpm install --frozen-lockfile` is a
+  minimal-install build-order artifact — the macp import is type-only, vitest passes unbuilt; CI
+  installs build workspace deps, hence green there), **workspace typecheck 45/45 at head**,
+  consumer sweep: no external type consumers of RunManifest/StageStatus/ForgeTaskResult/
+  TaskExecutor; only importer of the package is packages/mosaic via registerForgeCommand
+  (smoke test asserts registration/help only — cannot break). Digest gate (shaggy's) before==after
+  with both-arm reactivity controls.
+- CI red on #1276/#1277/#1278: lane-wide `test` failure only
+  (test-start-agent-session.sh:103, fred's guard mis-wired; #1270 unwires it). Fred measured log
+  content: one real byte-identical failure per pipeline (2456/2457/2458); 13 of ~14 `FAIL` grep
+  hits are passing fail-loud test NAMES. **The red carries no information about the RI changes.**
+- Non-blocking finding: README L141-143 + skills/mosaic-forge/SKILL.md document bare
+  `mosaic forge run`/`resume`, which now exits 1 FORGE_NO_EXECUTOR — fast-follow docs touch.
+- **Identity incident, ruled on by fred:** review 172 recorded under shared host principal
+  mos-dt-0, not fargo. Mechanism (measured, wrapper source): pr-review.sh resolves its acting login
+  from the tea login list only; no fargo tea login on this host → silent host-default fallback;
+  MOSAIC_GIT_IDENTITY is only read in detect-platform.sh get_gitea_token's fallback arm, never
+  reached. Exact-id read-back verifies against the writing token, so it passed while attribution
+  was wrong — durable-provenance machinery proves the write, not the seat. Fred's ruling: review
+  172 stands (substance/verdict/pin correct; label wrong); NO re-approval (one approval,
+  annotated, is the stronger record); fred posts the provenance correction under @fred with
+  --login fred-ms (hard-fail path); no fargo tea login ever (freeze + Jason's to authorize);
+  tooling gap filed by fred. Also explains (does not reopen) #1228's mos-dt-0 attribution.
+- Merge gate: all RI PRs queue behind fred's green #1270 (Jason's call).
+
+## Next
+
+1. Wave 2 dispatch: RI-2-002 (MACP fail-closed, mirror RI-2-001 pattern for
+   packages/macp/src/gate-runner.ts) + RI-4-001 (PRD authority). Two parallel workers max.
+2. Docs fast-follow (README + mosaic-forge skill) — fold into #1276 or a tiny docs card.
+3. RI-V-001 evidence at the end.
+
+— fargo, 2026-08-17

packages/mosaic/__tests__/platform/detect.test.ts

@@ -0,0 +1,74 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+
+// homedir/platform are read at call time, so they can be stubbed per case.
+vi.mock('node:os', async (importOriginal) => {
+  const actual = await importOriginal<typeof import('node:os')>();
+  return {
+    ...actual,
+    homedir: () => '/home/tester',
+    platform: () => mockPlatform,
+  };
+});
+
+let mockPlatform: NodeJS.Platform = 'linux';
+
+const { getShellProfilePath, detectShell } = await import('../../src/platform/detect.js');
+
+describe('getShellProfilePath', () => {
+  const originalShell = process.env['SHELL'];
+  const originalZdotdir = process.env['ZDOTDIR'];
+
+  beforeEach(() => {
+    mockPlatform = 'linux';
+    delete process.env['ZDOTDIR'];
+  });
+
+  afterEach(() => {
+    if (originalShell === undefined) delete process.env['SHELL'];
+    else process.env['SHELL'] = originalShell;
+    if (originalZdotdir === undefined) delete process.env['ZDOTDIR'];
+    else process.env['ZDOTDIR'] = originalZdotdir;
+  });
+
+  // The regression this guards: setupPath() in stages/finalize.ts appends the
+  // PATH export to whatever this returns. A line written to ~/.bashrc is
+  // unreachable to `bash -lc`, systemd units and agent seats, because Debian's
+  // default .bashrc returns early for non-interactive shells — so an install
+  // reported success and left `mosaic: command not found`. Same for .zshrc,
+  // which zsh only reads for interactive shells.
+  it('never targets an interactive-only rc file', () => {
+    for (const shell of ['/bin/bash', '/usr/bin/zsh']) {
+      process.env['SHELL'] = shell;
+      const profile = getShellProfilePath();
+      expect(profile).not.toMatch(/\.bashrc$/);
+      expect(profile).not.toMatch(/\.zshrc$/);
+    }
+  });
+
+  it('uses ~/.profile for bash', () => {
+    process.env['SHELL'] = '/bin/bash';
+    expect(getShellProfilePath()).toBe('/home/tester/.profile');
+  });
+
+  it('uses ~/.zshenv for zsh', () => {
+    process.env['SHELL'] = '/usr/bin/zsh';
+    expect(getShellProfilePath()).toBe('/home/tester/.zshenv');
+  });
+
+  it('honours ZDOTDIR for zsh', () => {
+    process.env['SHELL'] = '/usr/bin/zsh';
+    process.env['ZDOTDIR'] = '/custom/zdot';
+    expect(getShellProfilePath()).toBe('/custom/zdot/.zshenv');
+  });
+
+  it('falls back to ~/.profile for an unknown shell', () => {
+    process.env['SHELL'] = '/bin/somethingelse';
+    expect(detectShell()).toBe('unknown');
+    expect(getShellProfilePath()).toBe('/home/tester/.profile');
+  });
+
+  it('still routes fish to its own config', () => {
+    process.env['SHELL'] = '/usr/bin/fish';
+    expect(getShellProfilePath()).toBe('/home/tester/.config/fish/config.fish');
+  });
+});

packages/mosaic/framework/install.sh

@@ -35,6 +35,18 @@ SOURCE_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 TARGET_DIR="${MOSAIC_HOME:-$HOME/.config/mosaic}"
 INSTALL_MODE="${MOSAIC_INSTALL_MODE:-prompt}"
 
+# Normalize the ambient umask so directory modes are a property of the installer
+# and not of whatever shell invoked it (#1236). Debian/Ubuntu ship umask 002, so
+# every `mkdir -p` below yielded 0775 — and the fleet env boundary rejects any
+# managed directory with `mode & 0o022`, which made `mosaic fleet init --write`
+# impossible on a stock install of those distros. Fedora/RHEL ship 022 and did
+# not trip it, so the product worked or did not depending on the operator's
+# login shell. 022 is what this script already assumes it produces: see the
+# umask note in make_durable_snapshot, which restores to the ambient value
+# precisely so "every later sync copy and new framework dir" gets 0644/0755.
+# Now that value is 022 rather than whatever was inherited.
+umask 022
+
 # Deliberately parsed from "$@" (a real, explicit, per-invocation argument) —
 # never an environment variable — so this opt-out can never sit silently
 # inherited in a shell profile. See #869 Point-1 C2.
@@ -696,6 +708,52 @@ sync_framework
 mkdir -p "$TARGET_DIR/memory"
 mkdir -p "$TARGET_DIR/credentials"
 
+# Three directories must be 0700, not merely not-group-writable (#1236).
+# The fleet code guards them with two different masks in two different
+# languages, and the strict one wins:
+#
+#   assertPrivateManagedDirectory (fleet-reconciler.js, `mode & 0o077`)
+#       -> MOSAIC_HOME and MOSAIC_HOME/fleet, checked before the roster lock is
+#          taken, so every mutating `mosaic fleet` command dies at 0755.
+#   assert_private_directory (tools/fleet/start-agent-session.sh, `mode & 077`)
+#       -> MOSAIC_HOME/fleet/agents, checked before a pane is ever spawned.
+#
+# Their laxer siblings (`mode & 0o022`) accept 0755, which is why normalizing
+# the umask above is necessary and not sufficient — a correct umask-022 install
+# still produces 0755 and still cannot run `mosaic fleet init --write`. Say the
+# strict modes outright rather than inferring them from a umask.
+#
+# Only these. The rest of the tree is content, stays 0755, and is only ever
+# reached by the 0o022 checks, which 0755 satisfies.
+chmod 700 "$TARGET_DIR" 2>/dev/null || \
+  warn "Could not set 0700 on $TARGET_DIR — 'mosaic fleet' mutations will fail as unsafe-permissions."
+if [[ -d "$TARGET_DIR/fleet" ]]; then
+  chmod 700 "$TARGET_DIR/fleet" 2>/dev/null || \
+    warn "Could not set 0700 on $TARGET_DIR/fleet — 'mosaic fleet' mutations will fail as unsafe-permissions."
+fi
+# fleet/agents does not exist on a first install — the CLI creates it 0700 on
+# demand. It is chmod'd here for the UPGRADE case: a tree built under umask 002
+# has it at 0775, and the repair sweep below cannot rescue it, because stripping
+# group/other write from 0755 leaves 0750 and `mode & 077` is still non-zero.
+if [[ -d "$TARGET_DIR/fleet/agents" ]]; then
+  chmod 700 "$TARGET_DIR/fleet/agents" 2>/dev/null || \
+    warn "Could not set 0700 on $TARGET_DIR/fleet/agents — agent sessions will fail to start as unsafe-permissions."
+fi
+# credentials/ holds secrets and was never meant to be group-readable either.
+# It is not on the fleet boundary, so a failure here breaks nothing — but it is
+# the one directory where a silently-failed chmod leaves secrets group-readable,
+# which is precisely the failure worth a line in the output.
+chmod 700 "$TARGET_DIR/credentials" 2>/dev/null || \
+  warn "Could not set 0700 on $TARGET_DIR/credentials — stored secrets may be readable by other users on this host."
+
+# Repair an existing tree. The umask above only governs directories this run
+# creates, so a host installed under umask 002 before this fix keeps its 0775
+# dirs through every upgrade and stays broken. Strips group/other WRITE only —
+# never read or execute — so it can repair the boundary violation without
+# changing who can traverse or read anything. Scoped to directories: file modes
+# are the manifest's business, not this fix's.
+find "$TARGET_DIR" -type d -perm /022 -exec chmod go-w {} + 2>/dev/null || true
+
 # Reconcile contract files from defaults/ into the framework root: framework-owned
 # files (CONSTITUTION/AGENTS/STANDARDS) are overwritten every upgrade (a divergent
 # copy is backed up once); user-seeded files (TOOLS) are written on first install only.

packages/mosaic/framework/systemd/user/test-fleet-units.sh

@@ -128,6 +128,14 @@ EOF
 sleep 30
 EOF
   chmod 700 "$AGENT_BIN/mosaic"
+  # The launcher resolves the roster's runtime against PANE_PATH before it
+  # spawns anything (#1241), so the runtime this projection names has to be
+  # present here even though the fake `mosaic` above never execs it.
+  cat > "$AGENT_BIN/pi" <<'EOF'
+#!/bin/sh
+sleep 30
+EOF
+  chmod 700 "$AGENT_BIN/pi"
   server_environment_before=$(tmux -L "$TEST_SOCKET" show-environment -g | sort)
   server_sessions_before=$(tmux -L "$TEST_SOCKET" list-sessions | sort)
   if /usr/bin/env -i HOME="$HOLDER_HOME" PATH=/usr/bin:/bin MOSAIC_HOME="$AGENT_HOME" \

packages/mosaic/framework/tools/_scripts/mosaic-doctor

@@ -225,6 +225,54 @@ else
   warn "mosaic-ensure-sequential-thinking helper missing"
 fi
 
+# Fleet transport binary (#1240).
+#
+# `mosaic fleet --help` reads "Manage the local Mosaic tmux fleet" and every
+# roster the CLI scaffolds sets `transport: tmux`, but nothing in the install
+# path provides tmux and, until now, nothing here noticed it was absent. On a
+# greenfield host that produced a fleet which installed clean, started clean,
+# and had no live seat; `mosaic fleet ps` was the operator's first and only
+# signal that anything was wrong.
+#
+# The roster's own `transport:` is read rather than assumed, so a host that
+# declares something other than tmux is told about the binary it actually
+# needs. Absent a roster the check still runs — `mosaic fleet init` will
+# scaffold a tmux fleet on this host, and finding out beforehand is the point.
+#
+# `tools/install.sh` carries a deliberately parallel check at the end of its
+# summary. The two are separate because the installer must be able to say this
+# before the framework's own scripts are guaranteed to be on disk; keep their
+# wording in step.
+fleet_declared_transport() {
+  local roster="$MOSAIC_HOME/fleet/roster.yaml"
+  local declared=""
+
+  if [[ -f "$roster" ]]; then
+    declared="$(sed -n 's/^[[:space:]]*transport:[[:space:]]*//p' "$roster" | head -1 |
+      tr -d '"'\''' | tr -d '\r' | awk '{print $1}')"
+  fi
+
+  printf '%s\n' "${declared:-tmux}"
+}
+
+check_fleet_transport() {
+  local transport
+  transport="$(fleet_declared_transport)"
+
+  if command -v "$transport" >/dev/null 2>&1; then
+    pass "Fleet transport available: $transport"
+    return
+  fi
+
+  if [[ -f "$MOSAIC_HOME/fleet/roster.yaml" ]]; then
+    warn "Fleet transport '$transport' is not installed — this host has a roster and no seat can launch. Install it (e.g. sudo apt-get install -y $transport), then 'mosaic fleet start'."
+  else
+    warn "Fleet transport '$transport' is not installed — 'mosaic fleet' cannot run seats here. Install it (e.g. sudo apt-get install -y $transport) before 'mosaic fleet init'."
+  fi
+}
+
+check_fleet_transport
+
 # Legacy migration surfaces should no longer contain symlink trees.
 legacy_paths=(
   "$HOME/.claude/agent-guides"

packages/mosaic/framework/tools/_scripts/test-fleet-transport-check.sh

@@ -0,0 +1,215 @@
+#!/usr/bin/env bash
+# Covers the #1240 fleet-transport checks in `mosaic-doctor` and in
+# `tools/install.sh`.
+#
+# Both checks answer the same question — "can a seat actually launch on this
+# host?" — from two different places, because the installer has to be able to
+# answer it before the framework's own scripts are guaranteed to be on disk.
+# Two implementations of one rule is exactly the shape that drifts, so this
+# harness drives BOTH, in one file, from the same table of cases.
+#
+# The functions are extracted from the shipped scripts rather than copied here.
+# A test that carries its own copy of the logic is a test that keeps passing
+# after the shipped copy changes — the failure mode this whole change is about.
+# Extraction is by exact function header and a closing brace in column one; if
+# either script is reshaped so that stops matching, the extraction yields
+# nothing and this fails loudly instead of silently measuring an empty string.
+set -euo pipefail
+
+SCRIPT_DIR=$(cd -- "$(dirname -- "$0")" && pwd)
+DOCTOR="$SCRIPT_DIR/mosaic-doctor"
+# framework/tools/_scripts -> framework/tools -> framework -> mosaic -> packages -> repo
+INSTALLER=$(cd -- "$SCRIPT_DIR/../../../../.." && pwd)/tools/install.sh
+
+fail() {
+  echo "FAIL: $*" >&2
+  exit 1
+}
+
+[ -f "$DOCTOR" ] || fail "missing mosaic-doctor at $DOCTOR"
+[ -f "$INSTALLER" ] || fail "missing install.sh at $INSTALLER"
+
+ROOT=$(mktemp -d)
+trap 'rm -rf "$ROOT"' EXIT
+
+# The cases below run with PATH set to a directory that deliberately does not
+# contain a shell, and a PATH assignment on a command also governs how that
+# command is looked up — so bash has to be named absolutely or it becomes the
+# thing that is missing.
+BASH_BIN=$(command -v bash) || fail "host is missing 'bash'"
+
+# A PATH containing exactly the utilities these functions use and nothing else.
+# The absent-transport cases are only meaningful on a PATH where the transport
+# is genuinely unresolvable, and this host (like most) has tmux in /usr/bin —
+# so the system path cannot be part of the path under test.
+FAKE_BIN="$ROOT/bin"
+mkdir -p "$FAKE_BIN"
+for utility in sed head tr awk; do
+  utility_path=$(command -v "$utility") || fail "host is missing '$utility'"
+  ln -s "$utility_path" "$FAKE_BIN/$utility"
+done
+
+if PATH="$FAKE_BIN" command -v tmux >/dev/null 2>&1; then
+  fail "'tmux' is resolvable on the minimal test path; absent-transport cases are not measurable"
+fi
+
+# Extract a function by its exact header, up to a closing brace in column one.
+extract_function() {
+  local source_file="$1"
+  local function_name="$2"
+  local destination="$3"
+
+  awk -v name="$function_name" '
+    $0 == name "() {" { collecting = 1 }
+    collecting { print }
+    collecting && $0 == "}" { exit }
+  ' "$source_file" > "$destination"
+
+  grep -qF "$function_name() {" "$destination" ||
+    fail "could not extract '$function_name' from $source_file — has it been renamed or reshaped?"
+  # An unterminated extraction would be a syntax error the moment it is sourced,
+  # but saying so here names the cause instead of leaving a bash parse error.
+  bash -n "$destination" ||
+    fail "extracted '$function_name' does not parse; the closing brace was probably not found"
+}
+
+extract_function "$DOCTOR" fleet_declared_transport "$ROOT/doctor-declared.sh"
+extract_function "$DOCTOR" check_fleet_transport "$ROOT/doctor-check.sh"
+extract_function "$INSTALLER" check_fleet_transport "$ROOT/installer-check.sh"
+
+# Build a MOSAIC_HOME, optionally with a roster declaring a transport.
+make_home() {
+  local home="$ROOT/$1"
+  local declared="${2-}"
+
+  rm -rf "$home"
+  mkdir -p "$home"
+  if [ -n "$declared" ]; then
+    mkdir -p "$home/fleet"
+    cat > "$home/fleet/roster.yaml" <<EOF
+version: 2
+generation: 1
+transport: $declared
+agents: []
+EOF
+  fi
+  printf '%s\n' "$home"
+}
+
+# Run the doctor's check against a given home and path, capturing which
+# reporter the check chose. The real `pass` prints only under `--verbose` and
+# the real `warn` always prints; these stubs make both unconditional on
+# purpose, because what is under test is the severity the check selects, not
+# whether the default verbosity happens to show it. A check that warned where
+# it should pass would otherwise be invisible here.
+run_doctor_check() {
+  local home="$1"
+  local path="$2"
+
+  MOSAIC_HOME="$home" PATH="$path" "$BASH_BIN" --noprofile --norc -c '
+    set -euo pipefail
+    warn() { echo "[WARN] $*"; }
+    pass() { echo "[OK] $*"; }
+    MOSAIC_HOME="$1"
+    source "$2"
+    source "$3"
+    check_fleet_transport
+  ' _ "$home" "$ROOT/doctor-declared.sh" "$ROOT/doctor-check.sh" 2>&1
+}
+
+run_installer_check() {
+  local home="$1"
+  local path="$2"
+
+  MOSAIC_HOME="$home" PATH="$path" "$BASH_BIN" --noprofile --norc -c '
+    set -euo pipefail
+    warn() { echo "[WARN] $*"; }
+    C="" RESET=""
+    MOSAIC_HOME="$1"
+    source "$2"
+    check_fleet_transport
+  ' _ "$home" "$ROOT/installer-check.sh" 2>&1
+}
+
+# A transport that exists. Named tmux because that is what the default roster
+# declares; the binary never runs, it only has to resolve.
+PRESENT_BIN="$ROOT/present-bin"
+mkdir -p "$PRESENT_BIN"
+printf '#!/usr/bin/env bash\nexit 0\n' > "$PRESENT_BIN/tmux"
+chmod +x "$PRESENT_BIN/tmux"
+PATH_WITH_TMUX="$PRESENT_BIN:$FAKE_BIN"
+
+# ── absent, no roster ────────────────────────────────────────────────────────
+# Nothing has been configured yet, so the honest thing to point at is `init`.
+home=$(make_home no-roster)
+
+output=$(run_doctor_check "$home" "$FAKE_BIN")
+echo "$output" | grep -qF '[WARN]' || fail "doctor did not warn when tmux was absent"
+echo "$output" | grep -qF 'tmux' || fail "doctor warning did not name the transport"
+echo "$output" | grep -qF 'mosaic fleet init' || fail "doctor did not point a rosterless host at init"
+
+output=$(run_installer_check "$home" "$FAKE_BIN")
+echo "$output" | grep -qF '[WARN]' || fail "installer did not warn when tmux was absent"
+echo "$output" | grep -qF 'reports success and no seat comes up' ||
+  fail "installer warning did not say what the missing transport actually breaks"
+
+# ── absent, roster present ───────────────────────────────────────────────────
+# A configured fleet that cannot launch is a stronger statement than a
+# hypothetical one, and the message says so.
+home=$(make_home with-roster tmux)
+
+output=$(run_doctor_check "$home" "$FAKE_BIN")
+echo "$output" | grep -qF '[WARN]' || fail "doctor did not warn with a roster present and tmux absent"
+echo "$output" | grep -qF 'roster' || fail "doctor did not mention the roster it found"
+echo "$output" | grep -qF 'mosaic fleet start' || fail "doctor did not point a configured host at start"
+
+# ── present ──────────────────────────────────────────────────────────────────
+# Silence from the installer, and a pass (not a warning) from the audit.
+for home_name in no-roster with-roster; do
+  home="$ROOT/$home_name"
+
+  output=$(run_doctor_check "$home" "$PATH_WITH_TMUX")
+  if echo "$output" | grep -qF '[WARN]'; then
+    fail "doctor warned about the transport while tmux was present ($home_name)"
+  fi
+  echo "$output" | grep -qF '[OK]' || fail "doctor did not record a pass with tmux present ($home_name)"
+
+  output=$(run_installer_check "$home" "$PATH_WITH_TMUX")
+  if [ -n "$output" ]; then
+    fail "installer was not silent with tmux present ($home_name): $output"
+  fi
+done
+
+# ── the roster declares something other than tmux ────────────────────────────
+# The roster is read, not assumed. A host that declares a different transport
+# is told about the binary it actually needs, and never about tmux — being sent
+# to install the wrong package is worse than no advice at all.
+home=$(make_home other-transport zellij)
+
+output=$(run_doctor_check "$home" "$PATH_WITH_TMUX")
+echo "$output" | grep -qF 'zellij' || fail "doctor ignored the roster's declared transport"
+if echo "$output" | grep -qF 'tmux'; then
+  fail "doctor named tmux for a host whose roster declares zellij"
+fi
+
+output=$(run_installer_check "$home" "$PATH_WITH_TMUX")
+echo "$output" | grep -qF 'zellij' || fail "installer ignored the roster's declared transport"
+if echo "$output" | grep -qF 'tmux'; then
+  fail "installer named tmux for a host whose roster declares zellij"
+fi
+
+# ── a quoted or trailing-comment transport value ─────────────────────────────
+# YAML permits both and neither is exotic; a check that installs `tmux"` or
+# reads `tmux # default` as a binary name would send the operator nowhere.
+home=$(make_home quoted-transport '"tmux"   # the only transport today')
+
+output=$(run_doctor_check "$home" "$PATH_WITH_TMUX")
+echo "$output" | grep -qF '[OK] Fleet transport available: tmux' ||
+  fail "doctor did not parse a quoted/commented transport value: $output"
+
+output=$(run_installer_check "$home" "$PATH_WITH_TMUX")
+if [ -n "$output" ]; then
+  fail "installer did not parse a quoted/commented transport value: $output"
+fi
+
+echo "ok - fleet transport checks (mosaic-doctor + install.sh)"

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

@@ -286,6 +286,36 @@ _build_runtime_bin_prefix() {
 MOSAIC_RUNTIME_BIN_PREFIX=$(_build_runtime_bin_prefix)
 PANE_PATH=${MOSAIC_RUNTIME_BIN_PREFIX:+${MOSAIC_RUNTIME_BIN_PREFIX}:}/usr/local/bin:/usr/bin:/bin
 
+# #1241. The pane runs `mosaic yolo <runtime>` under PANE_PATH with a cleared
+# environment. A binary missing from *that* path is a pane that dies in under a
+# second, inside a session nobody is attached to, with its diagnostic scrolled
+# into a pane tmux then destroys. Resolve both here, before any effect, where
+# the failure is still attributable to the thing that caused it.
+#
+# `mosaic yolo <runtime>` runs checkRuntime(runtime) and the binary it looks for
+# is named exactly like the runtime, so resolving the runtime name is the same
+# question the pane will ask a moment later — asked while an operator can still
+# see the answer.
+_resolve_in_pane_path() {
+  PATH="$PANE_PATH" command -v -- "$1" 2>/dev/null
+}
+
+# Exit 69 (EX_UNAVAILABLE): the seat cannot be provided. Distinguished from the
+# 64 (EX_USAGE) rejections above, which mean the projection itself was bad —
+# here the data is fine and the host is not ready. Callers tell the individual
+# cases apart by `code=`, the same way fail_env's many codes share exit 64.
+fail_launch() {
+  local code="$1"
+  shift
+  echo "ERROR: agent launch aborted: code=${code} agent=${AGENT_NAME} $*" >&2
+  exit 69
+}
+
+for required_binary in mosaic "$MOSAIC_AGENT_RUNTIME"; do
+  _resolve_in_pane_path "$required_binary" >/dev/null ||
+    fail_launch missing-binary "'${required_binary}' is not on the pane PATH (${PANE_PATH})"
+done
+
 _ensure_claude_workdir_trusted() {
   local workdir="$1"
   local resolved
@@ -384,6 +414,19 @@ if [ -n "$PANE_PID" ]; then
   _start_heartbeat_sidecar "$AGENT_NAME" "$PANE_PID" \
     "$MOSAIC_HEARTBEAT_RUN_DIR" "$MOSAIC_HEARTBEAT_INTERVAL" || \
     echo "WARNING: heartbeat sidecar could not be started for $AGENT_NAME" >&2
+elif _tmux has-session -t "=${AGENT_NAME}:0.0" 2>/dev/null; then
+  # #1241. Session present, no pane PID after a second of retries. Whatever this
+  # is, it is not a seat an operator can use, so it is not a success either.
+  fail_launch pane-pid-unresolved \
+    "tmux reports the session but no pane PID after 5 attempts"
 else
-  echo "WARNING: could not resolve pane PID for $AGENT_NAME — heartbeat sidecar not started" >&2
+  # #1241. This branch used to print a WARNING about the heartbeat sidecar and
+  # exit 0. It is not a heartbeat problem: tmux destroys a session when its pane
+  # command exits, so an absent session one second after new-session means the
+  # runtime died on startup. Reporting it as success is what let `fleet start`
+  # return 0 over three dead panes — the launcher knew, and said the wrong thing
+  # at the wrong severity to the wrong layer.
+  fail_launch pane-did-not-survive \
+    "the pane exited immediately and tmux destroyed the session;" \
+    "run 'mosaic yolo ${MOSAIC_AGENT_RUNTIME}' in ${MOSAIC_AGENT_WORKDIR} to see why"
 fi

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

@@ -23,8 +23,26 @@ index=0
 if [ "${args[0]:-}" = -L ]; then index=2; fi
 case "${args[$index]:-}" in
   has-session)
+    # The holder always answers. MOSAIC_TEST_HELD_SESSIONS lets a case add
+    # other targets that should answer too — without it there is no way to
+    # model "tmux still reports the session" for a non-holder agent, and the
+    # launcher's pane-pid-unresolved branch is unreachable from this harness.
+    #
+    # A listed target answers only AFTER new-session, because the launcher asks
+    # this question twice about the same name: once before launching, where a
+    # yes means "already running, nothing to do, exit 0", and once after, where
+    # a yes means "the session survived". A shim that answered yes to both
+    # would short-circuit at the first and never reach the branch under test —
+    # it would look like coverage and measure the idempotency path instead.
     for argument in "${args[@]}"; do
       [ "$argument" = '=_holder:0.0' ] && exit 0
+      case " ${MOSAIC_TEST_HELD_SESSIONS:-} " in
+        *" $argument "*)
+          if tr '\0' '\n' < "${MOSAIC_TEST_TMUX_CALLS:?}" | grep -qxF new-session; then
+            exit 0
+          fi
+          ;;
+      esac
     done
     exit 1
     ;;
@@ -62,6 +80,30 @@ env -0 > "${MOSAIC_HOME:?}/fleet/pane-environment"
 SHIM
 chmod +x "$FAKE_BIN/mosaic"
 
+# The runtime the rosters below name. The launcher resolves it against PANE_PATH
+# before spawning (#1241), so it has to exist somewhere the pane would find it —
+# not merely on the launcher's own PATH.
+printf '#!/usr/bin/env bash\nexit 0\n' > "$FAKE_BIN/pi"
+chmod +x "$FAKE_BIN/pi"
+
+# PANE_PATH is derived partly from `npm config get prefix`. Left to the real npm
+# it would splice whatever the host has installed into the path under test, and
+# the missing-binary cases below would pass or fail by accident of the machine.
+cat > "$FAKE_BIN/npm" <<'SHIM'
+#!/usr/bin/env bash
+printf '%s\n' "${MOSAIC_TEST_NPM_PREFIX:-/nonexistent}"
+SHIM
+chmod +x "$FAKE_BIN/npm"
+
+# PANE_PATH always ends in the system path. A host that installs these there can
+# not measure the missing-binary cases at all, and a green run would mean
+# nothing — so say so instead of passing.
+for host_binary in mosaic pi; do
+  if PATH=/usr/local/bin:/usr/bin:/bin command -v "$host_binary" >/dev/null 2>&1; then
+    fail "host provides '$host_binary' in the system path; missing-binary cases are not measurable here"
+  fi
+done
+
 write_generated() {
   local home="$1"
   local agent="$2"
@@ -81,6 +123,19 @@ MOSAIC_TMUX_SOCKET=mosaic-test
 EOF
   chmod 600 "$home/fleet/agents/$agent.env.generated"
   mkdir -p "$home/work"
+  install_pane_binaries "$home"
+}
+
+# `$PANE_HOME/.npm-global/bin` is one of the prefixes the launcher folds into
+# PANE_PATH, so this is the pane's own view of "installed", distinct from the
+# launcher's PATH. Tests that need a binary *absent* remove it from here.
+install_pane_binaries() {
+  local pane_home="$1"
+  mkdir -p "$pane_home/.npm-global/bin"
+  local binary
+  for binary in mosaic pi; do
+    ln -sf "$FAKE_BIN/$binary" "$pane_home/.npm-global/bin/$binary"
+  done
 }
 
 run_start() {
@@ -88,6 +143,7 @@ run_start() {
   local agent="$2"
   HOME="$home" PATH="$FAKE_BIN:$PATH" MOSAIC_TEST_TMUX_CALLS="$TMUX_CALLS" \
     MOSAIC_TEST_PANE_PID="${MOSAIC_TEST_PANE_PID:-}" \
+    MOSAIC_TEST_HELD_SESSIONS="${MOSAIC_TEST_HELD_SESSIONS:-}" \
     MOSAIC_TEST_HOME="$home" \
     MOSAIC_TEST_FLEET_OWNER=123e4567-e89b-12d3-a456-426614174000 \
     MOSAIC_HOME="$home" "$START" "$agent"
@@ -98,7 +154,10 @@ run_start() {
 HOME_VALID="$ROOT/valid"
 AGENT_VALID="coder0"
 write_generated "$HOME_VALID" "$AGENT_VALID"
-run_start "$HOME_VALID" "$AGENT_VALID"
+# A live pane PID is part of what "valid launch" means. Until #1241 this case
+# ran with none, so the suite's one success path was itself a dead pane the
+# launcher reported as fine.
+MOSAIC_TEST_PANE_PID=$$ run_start "$HOME_VALID" "$AGENT_VALID"
 valid_args=$(tr '\0' '\n' < "$TMUX_CALLS")
 echo "$valid_args" | grep -qF new-session || fail "valid generated projection did not reach tmux"
 echo "$valid_args" | grep -qF 'mosaic' || fail "fixed mosaic launcher command missing"
@@ -245,6 +304,13 @@ PANE_BASH_ENV="$ROOT/pane-boundary.bash-env"
 printf 'MOSAIC_RUNTIME_BIN=%s\n' "$FAKE_BIN" > \
   "$HOME_PANE_BOUNDARY/fleet/agents/coder-pane-boundary.env.local"
 chmod 600 "$HOME_PANE_BOUNDARY/fleet/agents/coder-pane-boundary.env.local"
+# This case does not go through run_start, so its pane binaries come from
+# MOSAIC_RUNTIME_BIN=$FAKE_BIN in the env.local written above — not from the
+# symlinks install_pane_binaries planted under the generated home, which this
+# launcher never consults because HOME here is the trusted parent. That is a
+# legitimate resolution path, but it means dropping MOSAIC_RUNTIME_BIN from
+# this case on the belief that the symlinks cover it would break the #1241
+# binary check rather than exercise it.
 LD_PRELOAD='/not/loaded/by-clean-bootstrap.so' \
 BASH_ENV="$PANE_BASH_ENV" \
 MOSAIC_UNTRUSTED_SENTINEL='must-not-reach-pane' \
@@ -258,6 +324,7 @@ PATH="$PANE_STALE_PATH" \
     "MOSAIC_TEST_HOME=$PANE_TRUSTED_HOME" \
     MOSAIC_TEST_FLEET_OWNER=123e4567-e89b-12d3-a456-426614174000 \
     MOSAIC_TEST_EXECUTE_PANE=1 \
+    "MOSAIC_TEST_PANE_PID=$$" \
     "$START" coder-pane-boundary
 pane_args=$(tr '\0' '\n' < "$TMUX_CALLS")
 echo "$pane_args" | grep -qxF "HOME=$PANE_TRUSTED_HOME" || \
@@ -392,6 +459,75 @@ echo "$interaction_policy_args" | grep -qF 'new-session' && \
 echo "$output" | grep -qF 'operator interaction service requires runtime pi' || \
   fail "interaction pinned-policy check did not follow strict parsing"
 
+# #1241. The pane runs `mosaic yolo <runtime>` against PANE_PATH. A binary
+# missing from that path is a launch failure, and it has to be named before the
+# session is created — after it, the diagnostic dies with the pane.
+assert_missing_pane_binary_rejected() {
+  local binary="$1"
+  local home="$ROOT/missing-$binary"
+  local agent="coder-missing-$binary"
+  write_generated "$home" "$agent"
+  rm -f "$home/.npm-global/bin/$binary"
+
+  : > "$TMUX_CALLS"
+  local output
+  if output=$(MOSAIC_TEST_PANE_PID=$$ run_start "$home" "$agent" 2>&1); then
+    fail "launch succeeded with '$binary' absent from the pane PATH"
+  fi
+  echo "$output" | grep -qF 'code=missing-binary' || fail "missing '$binary' diagnostic missing"
+  echo "$output" | grep -qF "'$binary'" || fail "missing-binary diagnostic did not name $binary"
+  if tr '\0' '\n' < "$TMUX_CALLS" | grep -qF new-session; then
+    fail "launcher created a session it knew would die ($binary absent)"
+  fi
+}
+
+assert_missing_pane_binary_rejected mosaic
+assert_missing_pane_binary_rejected pi
+
+# #1241. tmux destroys a session when its pane command exits, so no pane PID a
+# second after new-session means the runtime died on startup. This used to be a
+# WARNING about the heartbeat sidecar followed by exit 0 — three layers above it
+# then reported a fleet that was not running.
+: > "$TMUX_CALLS"
+HOME_DEAD_PANE="$ROOT/dead-pane"
+write_generated "$HOME_DEAD_PANE" "coder-dead-pane"
+if output=$(MOSAIC_TEST_PANE_PID='' run_start "$HOME_DEAD_PANE" coder-dead-pane 2>&1); then
+  fail "launcher reported success over a pane that did not survive"
+fi
+echo "$output" | grep -qF 'code=pane-did-not-survive' || fail "dead-pane diagnostic missing"
+if echo "$output" | grep -qiF 'heartbeat'; then
+  fail "dead pane is still being reported as a heartbeat-sidecar problem"
+fi
+tr '\0' '\n' < "$TMUX_CALLS" | grep -qF new-session || \
+  fail "dead-pane case did not reach the launch it is measuring"
+
+# #1241, the other way a pane fails. Above, tmux destroyed the session and
+# has-session said so. Here the session is still there and no PID comes back
+# after the retries — a different fault (the pane is alive but unusable, or
+# tmux is answering inconsistently) that an operator has to be told apart from
+# a runtime that died on startup.
+#
+# This case exists because the branch that handles it shipped with nothing able
+# to reach it: the shim answered has-session only for the holder, so every
+# non-holder agent landed in the session-is-gone branch no matter what. A
+# defensive branch nothing exercises is the same shape as the bug this whole
+# change is about, one layer down.
+: > "$TMUX_CALLS"
+HOME_NO_PID="$ROOT/pane-no-pid"
+write_generated "$HOME_NO_PID" "coder-no-pid"
+if output=$(MOSAIC_TEST_PANE_PID='' MOSAIC_TEST_HELD_SESSIONS='=coder-no-pid:0.0' \
+  run_start "$HOME_NO_PID" coder-no-pid 2>&1); then
+  fail "launcher reported success over a session with no resolvable pane PID"
+fi
+echo "$output" | grep -qF 'code=pane-pid-unresolved' || \
+  fail "session-present/no-PID was not reported as pane-pid-unresolved: $output"
+if echo "$output" | grep -qF 'code=pane-did-not-survive'; then
+  fail "a session tmux still reports was diagnosed as a destroyed session"
+fi
+if echo "$output" | grep -qiF 'heartbeat'; then
+  fail "an unresolvable pane PID is still being reported as a heartbeat-sidecar problem"
+fi
+
 # Exact stop derives the socket exclusively from the validated generated
 # projection and ignores an ambient socket supplied by the caller.
 : > "$TMUX_CALLS"

packages/mosaic/framework/tools/quality/test-enumeration-exclusions.txt

@@ -32,10 +32,6 @@ packages/mosaic/framework/tools/tmux/test-send-message-socket.sh | requires a re
 packages/mosaic/framework/tools/tmux/test-send-message-verdict.sh | requires real tmux-pane fixtures on a throwaway socket; CI image ships no tmux; #1017 burndown (same condition as its sibling)
 
 # --- single-suite directories: unmeasured in CI ---
-packages/mosaic/framework/tools/fleet/test-start-agent-session.sh | unmeasured in CI image; stubs tmux via a fake bin dir, likely CI-fit; #1017 burndown
-packages/mosaic/framework/tools/glpi/test-list-http-status.sh | unmeasured in CI image; stub-based (#807 regression harness), likely CI-fit; #1017 burndown
-packages/mosaic/framework/tools/orchestrator/test-board-roll.sh | unmeasured in CI image; file-fixture based, likely CI-fit; #1017 burndown
-packages/mosaic/framework/tools/woodpecker/test-ci-wait-exit-matrix.sh | unmeasured in CI image; drives ci-wait.sh against a stub pipeline-status.sh, likely CI-fit; #1017 burndown
 
 # --- naming-boundary files the strict test-*.sh prefix cannot even name ---
 # (#1017: three independent censuses handled the microtest file three different

packages/mosaic/package.json

@@ -25,7 +25,7 @@
     "lint": "eslint src",
     "typecheck": "tsc --noEmit",
     "test": "vitest run --passWithNoTests && pnpm run test:framework-shell",
-    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.sh && python3 src/lease-broker/daemon_deadline_unittest.py && python3 src/lease-broker/normative_fragments_unittest.py && python3 src/lease-broker/promotion_binding_unittest.py && python3 src/lease-broker/promotion_trigger_unittest.py && python3 src/lease-broker/receipt_challenge_unittest.py && python3 src/lease-broker/context_recovery_unittest.py && python3 src/lease-broker/recovery_runtime_unittest.py && python3 src/lease-broker/recovery_b1_adversarial_unittest.py && python3 src/lease-broker/receipt_observer_client_unittest.py && python3 src/lease-broker/invariant_r_unittest.py && python3 src/lease-broker/framework_skill_portability_unittest.py && python3 src/mutator-gate/runtime_tools_unittest.py && python3 src/mutator-gate/runtime_launch_guard_unittest.py && python3 src/mutator-gate/version_coupling_unittest.py && python3 framework/tools/lease-broker/check-runtime-launches.py --root ../.. && bash framework/tools/codex/test-pr-diff-context.sh && bash framework/tools/qa/test-deps-preflight.sh && bash framework/tools/git/test-pr-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.sh && bash framework/tools/git/test-ci-queue-wait-branch-absent.sh && bash framework/tools/git/test-ci-queue-wait-tristate.sh && bash framework/tools/git/test-ci-queue-wait-github-checks.sh && bash framework/tools/git/test-pr-merge-queue-branch.sh && bash framework/tools/git/test-pr-merge-head-pin.sh && bash framework/tools/git/test-pr-merge-message-field.sh && bash framework/tools/git/test-git-credential-mosaic.sh && bash framework/tools/git/test-gitea-token-identity.sh && bash framework/tools/woodpecker/test-terminal-green-contract.sh && bash framework/tools/_scripts/test-install-ordering-guard.sh && bash framework/tools/_scripts/test-mosaic-init-rce.sh && bash framework/tools/tmux/agent-send.test.sh && bash framework/tools/wake/test-wake-store-ack.sh && bash framework/tools/wake/test-wake-store-enqueue-race.sh && bash framework/tools/wake/test-wake-digest-hmac.sh && bash framework/tools/wake/test-wake-digest-quarantine.sh && bash framework/tools/wake/test-wake-detector.sh && bash framework/tools/wake/test-wake-fn-oracle.sh && bash framework/tools/wake/test-wake-reconcile.sh && bash framework/tools/wake/test-wake-beacon.sh && bash framework/tools/wake/test-wake-preimage.sh && bash framework/tools/wake/test-wake-install.sh"
+    "test:framework-shell": "bash framework/tools/quality/scripts/check-test-enumeration.sh && bash framework/tools/quality/scripts/test-check-test-enumeration.sh && python3 src/lease-broker/daemon_deadline_unittest.py && python3 src/lease-broker/normative_fragments_unittest.py && python3 src/lease-broker/promotion_binding_unittest.py && python3 src/lease-broker/promotion_trigger_unittest.py && python3 src/lease-broker/receipt_challenge_unittest.py && python3 src/lease-broker/context_recovery_unittest.py && python3 src/lease-broker/recovery_runtime_unittest.py && python3 src/lease-broker/recovery_b1_adversarial_unittest.py && python3 src/lease-broker/receipt_observer_client_unittest.py && python3 src/lease-broker/invariant_r_unittest.py && python3 src/lease-broker/framework_skill_portability_unittest.py && python3 src/mutator-gate/runtime_tools_unittest.py && python3 src/mutator-gate/runtime_launch_guard_unittest.py && python3 src/mutator-gate/version_coupling_unittest.py && python3 framework/tools/lease-broker/check-runtime-launches.py --root ../.. && bash framework/tools/codex/test-pr-diff-context.sh && bash framework/tools/qa/test-deps-preflight.sh && bash framework/tools/git/test-pr-review-gitea-comment.sh && bash framework/tools/git/test-pr-review-repo-host-override.sh && bash framework/tools/git/test-ci-queue-wait-branch-absent.sh && bash framework/tools/git/test-ci-queue-wait-tristate.sh && bash framework/tools/git/test-ci-queue-wait-github-checks.sh && bash framework/tools/git/test-pr-merge-queue-branch.sh && bash framework/tools/git/test-pr-merge-head-pin.sh && bash framework/tools/git/test-pr-merge-message-field.sh && bash framework/tools/git/test-git-credential-mosaic.sh && bash framework/tools/git/test-gitea-token-identity.sh && bash framework/tools/woodpecker/test-terminal-green-contract.sh && bash framework/tools/_scripts/test-install-ordering-guard.sh && bash framework/tools/_scripts/test-mosaic-init-rce.sh && bash framework/tools/tmux/agent-send.test.sh && bash framework/tools/wake/test-wake-store-ack.sh && bash framework/tools/wake/test-wake-store-enqueue-race.sh && bash framework/tools/wake/test-wake-digest-hmac.sh && bash framework/tools/wake/test-wake-digest-quarantine.sh && bash framework/tools/wake/test-wake-detector.sh && bash framework/tools/wake/test-wake-fn-oracle.sh && bash framework/tools/wake/test-wake-reconcile.sh && bash framework/tools/wake/test-wake-beacon.sh && bash framework/tools/wake/test-wake-preimage.sh && bash framework/tools/wake/test-wake-install.sh && bash framework/tools/fleet/test-start-agent-session.sh && bash framework/tools/glpi/test-list-http-status.sh && bash framework/tools/orchestrator/test-board-roll.sh && bash framework/tools/woodpecker/test-ci-wait-exit-matrix.sh && bash framework/tools/_scripts/test-fleet-transport-check.sh"
   },
   "dependencies": {
     "@mosaicstack/brain": "workspace:*",

packages/mosaic/src/platform/detect.ts

@@ -1,4 +1,3 @@
-import { existsSync } from 'node:fs';
 import { join } from 'node:path';
 import { homedir, platform } from 'node:os';
 
@@ -22,15 +21,18 @@ export function getShellProfilePath(): string | null {
 
   const shell = detectShell();
   switch (shell) {
+    // Both of these deliberately avoid the interactive-only rc files.
+    // Debian's default .bashrc returns early for non-interactive shells, so a
+    // PATH line appended to it never runs for `bash -lc`, systemd units, or
+    // agent seats — an install could report success and still leave `mosaic`
+    // unreachable. .profile is read by login shells and sources .bashrc for
+    // interactive ones, so one line covers both; .zshenv is zsh's equivalent.
     case 'zsh': {
       const zdotdir = process.env['ZDOTDIR'] ?? home;
-      return join(zdotdir, '.zshrc');
+      return join(zdotdir, '.zshenv');
     }
-    case 'bash': {
-      const bashrc = join(home, '.bashrc');
-      if (existsSync(bashrc)) return bashrc;
+    case 'bash':
       return join(home, '.profile');
-    }
     case 'fish':
       return join(home, '.config', 'fish', 'config.fish');
     default:

tools/install.sh

@@ -309,6 +309,124 @@ require_cmd() {
   fi
 }
 
+# True if any shell rc file already puts $1 on PATH.
+#
+# Each file is tested for existence first and grepped one at a time, rather than
+# handed to a single `grep -qs ... "${rc_files[@]}"`. Handing grep a missing file
+# makes the exit status implementation-defined: GNU grep 3.11 returns 0 when -q
+# matched an earlier file, ugrep 7.5 returns 2 for the missing one regardless.
+# On the 2 path the caller reads "not present yet" and appends a duplicate PATH
+# line on every single install.
+path_entry_exists() {
+  local dir="$1" rc_file
+  for rc_file in "$HOME/.profile" "$HOME/.zshenv" "$HOME/.zshrc" "$HOME/.bashrc"; do
+    if [[ -f "$rc_file" ]] && grep -qF "$dir" "$rc_file"; then
+      return 0
+    fi
+  done
+  return 1
+}
+
+# Append `export PATH="$1:$PATH"` to the shell profile so $1 survives this
+# process. An `export` here reaches only the installer; every directory the
+# install leaves behind has to be written down somewhere a later shell reads.
+#
+# Deliberately NOT ~/.bashrc: Debian's default .bashrc returns early for
+# non-interactive shells, so a PATH line appended to the bottom of it is
+# unreachable to `bash -lc`, to systemd units, and to every agent seat — the
+# exact consumers that need these binaries. ~/.profile is read by login shells
+# and Debian's .profile sources .bashrc for interactive ones, so a single line
+# there reaches both. For zsh the always-sourced file is .zshenv, not .zshrc.
+#
+# $1 = directory to add, $2 = label for the comment line.
+# Returns 1 (having warned) if the profile could not be written.
+persist_on_path() {
+  local dir="$1" label="$2" profile
+
+  if path_entry_exists "$dir"; then
+    return 0
+  fi
+
+  if [[ -n "${ZSH_VERSION:-}" ]] || [[ "$(basename "${SHELL:-}")" == "zsh" ]]; then
+    profile="$HOME/.zshenv"
+  else
+    profile="$HOME/.profile"
+  fi
+
+  # Probe writability in a subshell. A redirection failure on a special built-in
+  # aborts the shell it runs in, so it has to be a child; and the redirection on
+  # the subshell is what silences the "Permission denied" the shell would
+  # otherwise print ahead of our own message.
+  if ! ( : >>"$profile" ) 2>/dev/null; then
+    warn "$dir is not on your PATH and $profile could not be written"
+    dim "  Add to your shell rc:  export PATH=\"$dir:\$PATH\""
+    return 1
+  fi
+
+  {
+    echo ""
+    echo "# $label"
+    echo "export PATH=\"$dir:\$PATH\""
+  } >>"$profile"
+  ok "Added $dir to PATH in $profile"
+  return 0
+}
+
+# Persist $PREFIX/bin on PATH instead of only warning about it.
+#
+# The warning it replaces was the last step of an otherwise successful install,
+# so the installer reported success and left `mosaic: command not found` — an
+# unattended install had no operator to read the advice and act on it.
+ensure_prefix_on_path() {
+  if [[ ":$PATH:" == *":$PREFIX/bin:"* ]]; then
+    return
+  fi
+
+  if path_entry_exists "$PREFIX/bin"; then
+    warn "$PREFIX/bin is in your shell profile but not in this shell"
+  elif ! persist_on_path "$PREFIX/bin" "Mosaic CLI"; then
+    return
+  fi
+  dim "  Run:  export PATH=\"$PREFIX/bin:\$PATH\"   (or start a new login shell)"
+}
+
+# Fleet transport binary (#1240).
+#
+# `mosaic fleet --help` reads "Manage the local Mosaic tmux fleet" and every
+# roster the CLI scaffolds sets `transport: tmux`, but nothing in this script
+# provides tmux and, until now, nothing in it mentioned tmux at all. A
+# greenfield host came out of this installer able to install a fleet, start a
+# fleet, and run no seat — the operator's first signal was `mosaic fleet ps`.
+#
+# Not a `require_cmd`: tmux is required by the fleet, not by mosaic. Plenty of
+# hosts install this to run `mosaic claude` and will never scaffold a roster,
+# and failing their install over a binary they do not need would be wrong. It
+# is a warning that names precisely what it blocks.
+#
+# `tools/_scripts/mosaic-doctor` carries a deliberately parallel check, so the
+# same host state gets the same answer from an audit as from an install. They
+# are separate implementations because this one has to work before the
+# framework's scripts are guaranteed to be on disk; keep their wording in step.
+check_fleet_transport() {
+  local transport=tmux
+  local roster="$MOSAIC_HOME/fleet/roster.yaml"
+  local declared=""
+
+  if [[ -f "$roster" ]]; then
+    declared="$(sed -n 's/^[[:space:]]*transport:[[:space:]]*//p' "$roster" | head -1 |
+      tr -d '"'\''' | tr -d '\r' | awk '{print $1}')"
+    [[ -n "$declared" ]] && transport="$declared"
+  fi
+
+  command -v "$transport" &>/dev/null && return 0
+
+  warn "Fleet transport '$transport' is not installed."
+  echo "  The Mosaic fleet runs its agent seats inside $transport. Without it,"
+  echo "  ${C}mosaic fleet start${RESET} reports success and no seat comes up."
+  echo "  Install it before using the fleet, e.g. ${C}sudo apt-get install -y $transport${RESET}"
+  echo "  (this does not affect ${C}mosaic claude${RESET} or the other single-runtime commands)."
+}
+
 installed_cli_version() {
   local json
   json="$(npm ls -g --depth=0 --json --prefix="$PREFIX" 2>/dev/null)" || true
@@ -516,8 +634,175 @@ install_next_cli_from_registry() {
   ok "Installed @next packages: CLI ${installed_cli}, gateway ${installed_gateway}"
 }
 
+# ─── node bootstrap ───────────────────────────────────────────────────────────
+#
+# Nothing on a greenfield host installs Node.js, yet this installer and the CLI
+# it installs both hard-require it. Measured on a clean Debian 13 image: the
+# installer stopped at `require_cmd node` with "Required command not found" and
+# nothing was installed, with no hint of how to proceed.
+#
+# Inlined rather than factored into a sibling file on purpose: this script is
+# fetched standalone by curl and has nothing to source.
+#
+# No-op when a suitable node is already on PATH, so it never fights an
+# operator's nvm/fnm/distro node.
+
+NODE_ROOT="${MOSAIC_NODE_ROOT:-$HOME/.mosaic/node}"
+NODE_BOOTSTRAP_VERSION="${MOSAIC_NODE_VERSION:-v22.23.2}"
+NODE_MIN_MAJOR="${MOSAIC_NODE_MIN_MAJOR:-20}"
+NODE_DIST_BASE="${MOSAIC_NODE_DIST_BASE:-https://nodejs.org/dist}"
+
+# Major version of the node at $1, or empty if it will not run.
+node_major_of() {
+  local candidate="$1" version
+  version="$("$candidate" -e 'process.stdout.write(process.versions.node)' 2>/dev/null)" || return 0
+  printf '%s' "${version%%.*}"
+}
+
+node_is_suitable() {
+  local major
+  major="$(node_major_of "$1")"
+  [[ -n "$major" ]] && [[ "$major" -ge "$NODE_MIN_MAJOR" ]]
+}
+
+install_node() {
+  local node_os node_arch tarball release_url work_dir extracted target node_bin
+
+  case "$(uname -s)" in
+    Linux)  node_os="linux" ;;
+    Darwin) node_os="darwin" ;;
+    *) fail "Unsupported OS '$(uname -s)'. Install Node.js >= $NODE_MIN_MAJOR manually."; return 1 ;;
+  esac
+
+  # Linux here means glibc. Node's official linux-x64 build is dynamically
+  # linked against glibc, so on musl (Alpine) the binary will not exec — but it
+  # fails visibly: node_is_suitable rejects it and ensure_node exits with
+  # "install Node.js manually". No silent breakage, just a wasted download.
+  # A musl host needs the unofficial build, which is out of scope here.
+  case "$(uname -m)" in
+    x86_64|amd64)  node_arch="x64" ;;
+    aarch64|arm64) node_arch="arm64" ;;
+    armv7l)        node_arch="armv7l" ;;
+    *) fail "Unsupported architecture '$(uname -m)'. Install Node.js >= $NODE_MIN_MAJOR manually."; return 1 ;;
+  esac
+
+  # .tar.gz rather than the smaller .tar.xz: gzip is universally present, xz is
+  # not, and a minimal image is exactly the case this exists to handle.
+  tarball="node-${NODE_BOOTSTRAP_VERSION}-${node_os}-${node_arch}.tar.gz"
+  release_url="${NODE_DIST_BASE}/${NODE_BOOTSTRAP_VERSION}"
+
+  work_dir="$(mktemp -d "${TMPDIR:-/tmp}/mosaic-node-XXXXXX")"
+
+  info "Installing Node.js $NODE_BOOTSTRAP_VERSION ($node_os-$node_arch) to $NODE_ROOT…"
+
+  if ! curl -fsSL "${release_url}/${tarball}" -o "$work_dir/$tarball"; then
+    fail "Download failed: ${release_url}/${tarball}"
+    rm -rf "$work_dir"; return 1
+  fi
+
+  # Trust assumption, stated so nobody has to infer it: this verifies INTEGRITY
+  # (the tarball matches the manifest), not AUTHENTICITY (the manifest is
+  # genuinely Node's). The only thing establishing that is TLS to
+  # $NODE_DIST_BASE. Node publishes SHASUMS256.txt.sig signed by its release
+  # keys and we do not check it, which is on par with nvm but means pointing
+  # MOSAIC_NODE_DIST_BASE at an untrusted mirror has no signature backstop.
+  # Tracked as a hardening follow-up (raised by scooby in the #1229 review).
+  if ! curl -fsSL "${release_url}/SHASUMS256.txt" -o "$work_dir/SHASUMS256.txt"; then
+    fail "Could not fetch SHASUMS256.txt; refusing to install an unverified runtime."
+    rm -rf "$work_dir"; return 1
+  fi
+
+  # Keep only our artifact's line, so a missing entry is an error not a pass.
+  if ! grep " ${tarball}\$" "$work_dir/SHASUMS256.txt" >"$work_dir/expected.sha256"; then
+    fail "$tarball has no entry in SHASUMS256.txt; refusing to install."
+    rm -rf "$work_dir"; return 1
+  fi
+
+  if ! (cd "$work_dir" && verify_sha256 expected.sha256); then
+    fail "Checksum mismatch for $tarball; refusing to install."
+    rm -rf "$work_dir"; return 1
+  fi
+  ok "Checksum verified"
+
+  tar xzf "$work_dir/$tarball" -C "$work_dir"
+  extracted="$work_dir/node-${NODE_BOOTSTRAP_VERSION}-${node_os}-${node_arch}"
+  if [[ ! -x "$extracted/bin/node" ]]; then
+    fail "Extracted archive has no bin/node"
+    rm -rf "$work_dir"; return 1
+  fi
+
+  mkdir -p "$NODE_ROOT"
+  target="$NODE_ROOT/$NODE_BOOTSTRAP_VERSION"
+  rm -rf "$target.incoming"
+  mv "$extracted" "$target.incoming"
+  rm -rf "$target"
+  mv "$target.incoming" "$target"
+  ln -sfn "$NODE_BOOTSTRAP_VERSION" "$NODE_ROOT/current"
+  rm -rf "$work_dir"
+
+  node_bin="$NODE_ROOT/current/bin"
+  if ! node_is_suitable "$node_bin/node"; then
+    fail "Installed node at $node_bin/node did not run"
+    return 1
+  fi
+
+  export PATH="$node_bin:$PATH"
+  ok "Node.js $(node -v) installed with npm $(npm -v 2>/dev/null || echo '?')"
+  return 0
+}
+
+# Make the Mosaic-managed Node reachable from the next shell as well as this
+# one. Measured on a greenfield canary run: without this the install finished
+# rc=0, wrote $PREFIX/bin to ~/.profile, and the next login shell found `mosaic`
+# and then died on `env: 'node': No such file or directory` — the CLI is a Node
+# script, so a CLI on PATH without its runtime is a successful install that
+# produces a broken command.
+persist_node_on_path() {
+  persist_on_path "$NODE_ROOT/current/bin" "Mosaic-managed Node.js" || true
+}
+
+ensure_node() {
+  if command -v node &>/dev/null && node_is_suitable node; then
+    return 0
+  fi
+
+  # A previous run may have installed one that is not on this shell's PATH.
+  if node_is_suitable "$NODE_ROOT/current/bin/node"; then
+    export PATH="$NODE_ROOT/current/bin:$PATH"
+    persist_node_on_path
+    return 0
+  fi
+
+  if [[ "${MOSAIC_SKIP_NODE_BOOTSTRAP:-0}" == "1" ]]; then
+    fail "No suitable Node.js and MOSAIC_SKIP_NODE_BOOTSTRAP=1; refusing to download."
+    echo "  Install Node.js >= $NODE_MIN_MAJOR yourself, then re-run this script."
+    exit 1
+  fi
+
+  require_cmd curl
+  require_cmd tar
+
+  # sha256sum on Linux, shasum on macOS. Verification is not optional: without a
+  # checksum this would install an unauthenticated runtime.
+  if command -v sha256sum &>/dev/null; then
+    verify_sha256() { sha256sum -c --status "$1"; }
+  elif command -v shasum &>/dev/null; then
+    verify_sha256() { shasum -a 256 -c --status "$1"; }
+  else
+    fail "sha256sum or shasum required to verify the Node.js download"
+    exit 1
+  fi
+
+  if ! install_node; then
+    fail "Could not bootstrap Node.js. Install Node.js >= $NODE_MIN_MAJOR and re-run."
+    exit 1
+  fi
+  persist_node_on_path
+}
+
 # ─── preflight ────────────────────────────────────────────────────────────────
 
+ensure_node
 require_cmd node
 require_cmd npm
 
@@ -682,11 +967,7 @@ if [[ "$FLAG_CLI" == "true" ]]; then
     ensure_monorepo
     install_cli_from_source
 
-    # PATH check for npm prefix
-    if [[ ":$PATH:" != *":$PREFIX/bin:"* ]]; then
-      warn "$PREFIX/bin is not on your PATH"
-      dim "  Add to your shell rc:  export PATH=\"$PREFIX/bin:\$PATH\""
-    fi
+    ensure_prefix_on_path
   elif is_next_registry_lane; then
     info "Next mode — trying fast npm @next install from ${REGISTRY}…"
     if install_next_cli_from_registry; then
@@ -699,11 +980,7 @@ if [[ "$FLAG_CLI" == "true" ]]; then
       export MOSAIC_GATEWAY_SKIP_NPM_INSTALL=1
     fi
 
-    # PATH check for npm prefix
-    if [[ ":$PATH:" != *":$PREFIX/bin:"* ]]; then
-      warn "$PREFIX/bin is not on your PATH"
-      dim "  Add to your shell rc:  export PATH=\"$PREFIX/bin:\$PATH\""
-    fi
+    ensure_prefix_on_path
   else
     if [[ -z "$LATEST" ]]; then
       warn "Could not reach registry at $REGISTRY — skipping npm CLI."
@@ -721,11 +998,7 @@ if [[ "$FLAG_CLI" == "true" ]]; then
       ok "CLI is at or ahead of registry ($CURRENT ≥ $LATEST)."
     fi
 
-    # PATH check for npm prefix
-    if [[ ":$PATH:" != *":$PREFIX/bin:"* ]]; then
-      warn "$PREFIX/bin is not on your PATH"
-      dim "  Add to your shell rc:  export PATH=\"$PREFIX/bin:\$PATH\""
-    fi
+    ensure_prefix_on_path
   fi
 fi
 
@@ -870,6 +1143,11 @@ if [[ "$FLAG_CHECK" == "false" ]]; then
   ok "Done."
 fi
 
+# Fleet readiness (#1240). Runs in both normal and --check mode: "what is the
+# state of this host" is exactly the question --check is asked, and a host that
+# cannot run a seat should not have to discover it from `fleet ps`.
+check_fleet_transport
+
 } # end main
 
 main "$@"