feat(orchestration): retry <runId> — authored by headless pi worker (#26, #27)

Collaboration record (conductor loop, docs/plans/CONDUCTOR.md):
- round 1 (worker session worker-1, 2m28s): retry implemented per spec
- conductor live test exposed spec gap: direct invocation lacked
  launcher env exports
- round 2 (same worker session, 59s): spawnEnv made self-sufficient,
  but used PI_* where compose interpolates MOSAIC_*
- conductor hotfix: 3-line rename to MOSAIC_PROVIDER/MOSAIC_MODEL/
  MOSAIC_DATA_ROOT

Final: node scripts/mosaic-task.mjs retry <runId> re-executes a run's
task snapshot as a new run; live retry replied REMEMBERED; all suites
green (24/32/14 + verify).

Known limitation: retrying a run whose task used a RELATIVE mission path
resolves it against the temp dir; lineage tracking deferred.

Closes #25, closes #26, closes #27

tasks/worker-retry-refine.json

@@ -0,0 +1,9 @@
+{
+  "taskVersion": 1,
+  "id": "t-worker-retry-refine",
+  "prompt": "Follow-up on your last change to scripts/mosaic-task.mjs (the retry operation). Conductor review found one defect: runTask builds spawnEnv from process.env, so a direct 'node scripts/mosaic-task.mjs retry <runId>' invocation lacks the launcher-exported variables and compose fails with: required variable MOSAIC_IMAGE_TAG is missing.\n\nFIX (in runTask, not retryRun): make spawnEnv self-sufficient —\n1. spawnEnv.PI_PROVIDER = resolved.execution.provider; spawnEnv.PI_MODEL = resolved.execution.model (from the already-loaded resolved config).\n2. spawnEnv.MOSAIC_IMAGE_TAG = 'mosaic-poc-agent:' + <pinned pi version> + '-r' + <RELEASE file content trimmed>, reading RELEASE and package.json the same way scripts/common.sh load_release does.\nKeep the change minimal; do not touch other files; keep code style.\n\nSELF-CHECK: node --check scripts/mosaic-task.mjs must pass.\nWhen finished, reply with exactly: REFINE_DONE",
+  "workspace": "stack-repo",
+  "capabilities": { "tools": ["read", "write", "edit", "bash"] },
+  "session": "worker-1",
+  "timeoutSeconds": 600
+}

tasks/worker-retry.json

@@ -0,0 +1,9 @@
+{
+  "taskVersion": 1,
+  "id": "t-worker-retry",
+  "prompt": "You are working alone inside a git repository checkout (your current working directory). Implement a new feature in scripts/mosaic-task.mjs.\n\nFEATURE: add a 'retry <runId>' operation alongside the existing 'validate | run | show | list' operations.\n\nBEHAVIOR: 'retry <runId>' re-executes a previously recorded run. Steps: (1) validate the runId argument with the same pattern showRun uses; (2) load the config exactly like showRun does; (3) locate the run directory under the runs root; if it does not exist, fail with exit code 4 and the message 'run not found: <runId>'; (4) read that run directory's task.json snapshot; if unreadable, fail with exit code 4; (5) write the snapshot to a temp file and execute it through the EXISTING runTask(path) function so a brand-new run is created — do not duplicate any execution logic; (6) exit with whatever exit code the new run produced.\n\nCONSTRAINTS: reuse runTask; do not refactor unrelated code; do not touch any file other than scripts/mosaic-task.mjs; keep the existing code style; update the default usage error message to include retry.\n\nSELF-CHECK (run it yourself with the bash tool): node --check scripts/mosaic-task.mjs must pass.\n\nWhen finished, reply with exactly: RETRY_DONE",
+  "workspace": "stack-repo",
+  "capabilities": { "tools": ["read", "write", "edit", "bash"] },
+  "session": "worker-1",
+  "timeoutSeconds": 600
+}