emrg: global cross-project session index (rant 2026-08-13T16:42:22)

[argszero]

Summary

Implements the host's cross-project session global index design: a single ~/.emrg/sessions_index.json mapping session_id → absolute session directory, so any session can locate and read another project's conversation records.

Design (host-finalized, minimal index)

The index stores only the id→path map; everything else (title, message_count, updated_at, history, memory) is read on demand from the target session's meta.json / history.jsonl / memory/MEMORY.md.

Changes

• emrg/sessions_index.py (new): upsert_session_index / remove_session_index / rebuild_sessions_index with atomic write (tmp + os.replace), corrupt-file tolerance (never raises), idempotent upsert (skips rewrite when the path is unchanged). The startup scan walks ~/.emrg recursively (pruning install/.git/node_modules/.venv/etc.) plus each registered project path.
• emrg/session.py: Session._save_meta_with_title upserts (create/append/compact/rename/clear all funnel through it); Session.delete removes the entry.
• emrg/server/daemon.py: _build_system_prompt injects config_dir; serve() calls _rebuild_sessions_index() at startup (best-effort, never crashes).
• emrg/server/prompts/system.j2: documents the discovery flow (read index → meta.json → history.jsonl → memory).
• tests/conftest.py: autouse fixture redirects the index to a per-test tmp file (hermeticity — prevents the whole session suite from polluting the host's real index, same class as the projects.yml leak guard).

Verification

• +20 tests (tests/test_sessions_index.py): 779→799; full suite green.
• import + CLI checks green.
• system.j2 renders the new block correctly.

Acceptance

• New session → index entry appears; compact/rewind/clear/rename → path unchanged (idempotent).
• Delete → entry removed; daemon restart → startup scan backfills pre-existing + unregistered-project sessions.
• Any session can read the index to find another project's session.

[argszero]

✅ LGTM — cycle (1/3)

Full review of the cross-project session index (rant 2026-08-13T16:42:22), head 42520c7, 7 files +443/-1:

• emrg/sessions_index.py (new, 181 lines): clean minimal design — index stores only session_id → absolute dir; atomic writes (mkstemp + os.replace), corrupt/missing/non-dict loads → empty dict, idempotent upsert (skips rewrite when path unchanged — mtime-bump test pins this), prune-dirs set keeps the recursive ~/.emrg scan fast (install/, node_modules/, .venv, .git, logs...).
• Write/delete hooks: Session._save_meta_with_title (create/append/compact/rename/clear all funnel through it) upserts; Session.delete removes. Correct single-funnel placement.
• Daemon startup backfill _rebuild_sessions_index(): covers registered projects (projects.yml paths) + unregistered nested under config_root; best-effort (try/except → debug log, never crashes startup); _projects_log confirmed present (daemon.py:175).
• Prompt: config_dir injected into system.j2 context (import confirmed, daemon.py:31) + Cross-Session Discovery section — clean, tool-based (read index → meta.json → history.jsonl → memory).
• Test isolation: autouse conftest fixture redirects the index to tmp_path (same class as the projects.yml leak guard) — prevents the suite from polluting the real ~/.emrg index.
• Verification: 20/20 new tests pass; full suite 799 passed (matches Agent.md doc count 779→799); client import + emrg --help OK.

No issues found. Needs 2 more independent-cycle ✅ to merge.

[pm25coder]

Tested end-to-end on branch head (checked out locally, full suite):

[argszero]

✅ LGTM — cycle (2/3).

Fresh independent re-verification of head 42520c7 (post-#755 merge, no file overlap):

• Import graph: sessions_index.py imports only emrg.config (config_dir) — no cycle (config imports nothing from session/sessions_index). session.py adds from emrg.sessions_index import ... alongside its existing emrg.memory import; full suite + from emrg.client.app import run_client already green.
• Single-funnel upsert: _save_meta_with_title (the one path create/append/compact/rename/clear all funnel through) calls upsert_session_index exactly once at the end; delete calls remove_session_index after shutil.rmtree. Verified via grep on the actual head.
• Idempotency: upsert short-circuits when the path is unchanged (mtime-bump test pins it), so repeated meta saves don't rewrite the index file.
• Startup backfill wired at daemon.py:298 (_rebuild_sessions_index before the scheduler starts), best-effort try/except → debug log.
• Prompt: ctx["config_dir"] injected at daemon.py:1082, consumed by the new Cross-Session Discovery section in system.j2.
• Hermeticity: autouse conftest fixture (line 57) redirects sessions_index_path to tmp — prevents the session suite from polluting the real ~/.emrg/sessions_index.json.

CI green (test + test-windows). No conflict with the just-merged #755 (that PR touched only i18n.js; this PR touches no GUI files). Needs 1 more independent-cycle ✅.

[argszero]

✅ LGTM — cycle (3/3)

Third independent-cycle approval. Re-confirmed on head 42520c7:

• No overlap with just-merged #755 (that touched only i18n.js; this PR touches no GUI files) — mergeable with master d89811b.
• Imports: sessions_index.py → only emrg.config (no cycle); session.py imports it alongside emrg.memory.
• Write hooks single-funnel through _save_meta_with_title (create/append/compact/rename/clear); delete removes from index after rmtree.
• Startup backfill wired at daemon.py:298 (before scheduler), best-effort.
• Prompt: config_dir → system.j2 Cross-Session Discovery.
• Test hermeticity: autouse fixture redirects index to tmp.
• CI test + test-windows PASS (31683984369).

3 consecutive ✅ from 3 cycles — merging.