Implement AGENTIC-WP-0011 kaizen correlation follow-up

Add bidirectional doc links (PRD §9.1, README, DESIGN §11), session-close
HELIX_* env convention, stable digest JSON contract, and digest_lookup CLI
for read-only correlate lookups. All tasks done; 163 tests green.

session_memory/digest_lookup.py

@@ -0,0 +1,76 @@
+"""Read a single session digest from the local store (AGENTIC-WP-0011 T03).
+
+Thin read path for ``kaizen-agentic metrics correlate`` and other consumers.
+Does not run ingest.
+
+Usage:
+    python -m session_memory.digest_lookup <session_uid> [--json]
+    HELIX_STORE_DB=/abs/path/to/mem.db python -m session_memory.digest_lookup <uid>
+"""
+
+from __future__ import annotations
+
+import argparse
+import json
+import os
+import sys
+
+from .core.store import Store
+from .ingest import _expand, load_config
+
+
+def resolve_store_paths(*, config_path: str | None = None) -> tuple[str, str]:
+    """Resolve db + blob paths from HELIX_STORE_DB or config.toml [store]."""
+    env_db = os.environ.get("HELIX_STORE_DB")
+    if env_db:
+        db_path = _expand(env_db)
+        blob_dir = os.path.join(os.path.dirname(db_path), "blobs")
+        return db_path, blob_dir
+
+    here = os.path.dirname(os.path.abspath(__file__))
+    cfg_path = config_path or os.path.join(here, "config.toml")
+    store_cfg = load_config(cfg_path).get("store", {})
+    return _expand(store_cfg.get("db_path", "session_memory/.store/mem.db")), _expand(
+        store_cfg.get("blob_dir", "session_memory/.store/blobs")
+    )
+
+
+def lookup_digest(session_uid: str, *, config_path: str | None = None) -> dict | None:
+    db_path, blob_dir = resolve_store_paths(config_path=config_path)
+    store = Store(db_path, blob_dir)
+    try:
+        return store.get_digest(session_uid)
+    finally:
+        store.close()
+
+
+def main(argv: list[str] | None = None) -> int:
+    here = os.path.dirname(os.path.abspath(__file__))
+    ap = argparse.ArgumentParser(
+        description="Read one session digest from the Helix Forge store (no ingest)."
+    )
+    ap.add_argument("session_uid", help="Normalized session uid, e.g. claude:abc-123")
+    ap.add_argument("--config", default=os.path.join(here, "config.toml"),
+                    help="config.toml when HELIX_STORE_DB is unset")
+    ap.add_argument("--json", action="store_true", help="print digest JSON to stdout")
+    args = ap.parse_args(argv)
+
+    digest = lookup_digest(args.session_uid, config_path=args.config)
+    if digest is None:
+        print(f"digest not found: {args.session_uid}", file=sys.stderr)
+        return 1
+
+    if args.json:
+        print(json.dumps(digest, indent=2, sort_keys=True))
+    else:
+        cost = digest.get("cost") or {}
+        tokens = cost.get("input_tokens", 0) + cost.get("output_tokens", 0)
+        print(f"session_uid: {digest.get('session_uid')}")
+        print(f"repo: {digest.get('repo')}  flavor: {digest.get('flavor')}")
+        print(f"outcome: {digest.get('outcome')}  tokens: {tokens}")
+        print(f"started_at: {digest.get('started_at')}  ended_at: {digest.get('ended_at')}")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())