feat(fleet): brain-home split — fleet state under ~/.mosaic, templates stay config-home (#1298)

Co-authored-by: Jason Woltje <[email protected]>
2026-08-18 03:23:15 +00:00
parent 8199261caa
commit a80bae950d
16 changed files with 498 additions and 21 deletions
@@ -0,0 +1,76 @@
+import { existsSync } from 'node:fs';
+import { homedir } from 'node:os';
+import { join, resolve } from 'node:path';
+
+/**
+ * Overridable resolution inputs (tests inject tmp homes; production reads
+ * the environment and the real home directory).
+ */
+export interface BrainHomeOptions {
+  /** Explicit brain home; defaults to `MOSAIC_BRAIN_HOME`. */
+  readonly envBrainHome?: string;
+  /**
+   * Canonical homes used for adoption. Defaults derive from the real
+   * `homedir()`: `{ brain: ~/.mosaic, configDefault: ~/.config/mosaic }`.
+   */
+  readonly homes?: { readonly brain: string; readonly configDefault: string };
+}
+
+/**
+ * Brain-home resolution — the three-tree fleet split (stack canon
+ * `docs/STRUCTURE-CANON.md` §2, first carried by the USC estate brain):
+ *
+ *   config home (~/.config/mosaic)  framework templates + dispatch state:
+ *                                   fleet/roles (baseline), fleet/roster.yaml,
+ *                                   fleet/run (heartbeats), fleet/services
+ *   brain home  (~/.mosaic)         user-owned fleet state, committed:
+ *                                   fleet/agents/<seat>.env.*, fleet/roles.local,
+ *                                   fleet/profiles working copies
+ *
+ * Resolution order:
+ *   1. `MOSAIC_BRAIN_HOME` env (explicit, always wins)
+ *   2. canonical `~/.mosaic` — adopted ONLY when mosaicHome is the real
+ *      default config home AND `~/.mosaic/fleet/agents` exists. Custom
+ *      `--mosaic-home` values (tests, sandboxes, canaries) never trigger
+ *      adoption, keeping them hermetic and deterministic.
+ *   3. mosaicHome itself (legacy single-tree behavior).
+ */
+export function resolveBrainHome(mosaicHome: string, options: BrainHomeOptions = {}): string {
+  const explicit = options.envBrainHome ?? process.env['MOSAIC_BRAIN_HOME'];
+  if (explicit !== undefined && explicit.trim() !== '') {
+    return explicit;
+  }
+  const homes = options.homes ?? {
+    brain: join(homedir(), '.mosaic'),
+    configDefault: join(homedir(), '.config', 'mosaic'),
+  };
+  if (resolve(mosaicHome) !== resolve(homes.configDefault)) {
+    return mosaicHome;
+  }
+  return existsSync(join(homes.brain, 'fleet', 'agents')) ? homes.brain : mosaicHome;
+}
+
+/** True when fleet state resolves somewhere other than the config home. */
+export function brainHomeIsActive(mosaicHome: string, options: BrainHomeOptions = {}): boolean {
+  return resolve(resolveBrainHome(mosaicHome, options)) !== resolve(mosaicHome);
+}
+
+/** Fleet state root (brain home when active, else the config home). */
+export function fleetStateDir(mosaicHome: string, options: BrainHomeOptions = {}): string {
+  return join(resolveBrainHome(mosaicHome, options), 'fleet');
+}
+
+/** Seat launch envs — `<brainHome>/fleet/agents` when a brain is active. */
+export function fleetAgentEnvDir(mosaicHome: string, options: BrainHomeOptions = {}): string {
+  return join(fleetStateDir(mosaicHome, options), 'agents');
+}
+
+/** PRESERVE-protected persona override layer — `<brainHome>/fleet/roles.local`. */
+export function fleetRolesLocalDir(mosaicHome: string, options: BrainHomeOptions = {}): string {
+  return join(fleetStateDir(mosaicHome, options), 'roles.local');
+}
+
+/** System-type profiles (user working copies) — `<brainHome>/fleet/profiles`. */
+export function fleetProfilesDir(mosaicHome: string, options: BrainHomeOptions = {}): string {
+  return join(fleetStateDir(mosaicHome, options), 'profiles');
+}