session-memory Phase 0: session digest + outcome heuristic (T04)

- session_memory/core/digest.py: build_digest (cost totals, kind/tool
  histograms, markers, snippets) + cross-flavor infer_outcome heuristic;
  analyze() promotes Tier1->Tier2 and sets analyzed_at (-> evictable)
- tests/test_digest.py

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_digest.py

@@ -0,0 +1,82 @@
+"""Digest tests (T04): outcome heuristic + Tier 2 promotion."""
+
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from session_memory.adapters.claude import Normalized  # noqa: E402
+from session_memory.core.digest import analyze, build_digest, infer_outcome  # noqa: E402
+from session_memory.core.schema import Cost, Session, SessionEvent  # noqa: E402
+from session_memory.core.store import Store  # noqa: E402
+
+
+def _ev(uid, seq, kind, **kw):
+    return SessionEvent(session_uid=uid, seq=seq, kind=kind, **kw)
+
+
+def test_infer_outcome_abandoned():
+    uid = "claude:s"
+    assert infer_outcome([_ev(uid, 0, "user_msg")]) == "abandoned"
+
+
+def test_infer_outcome_success_on_passing_test():
+    uid = "claude:s"
+    events = [
+        _ev(uid, 0, "user_msg"),
+        _ev(uid, 1, "assistant_msg"),
+        _ev(uid, 2, "test_run", tool="Bash"),
+        _ev(uid, 3, "tool_result", payload_ref="b3"),
+    ]
+    assert infer_outcome(events, {"b3": "6 passed in 0.4s"}) == "success"
+
+
+def test_infer_outcome_fail_on_failing_test():
+    uid = "claude:s"
+    events = [
+        _ev(uid, 0, "user_msg"),
+        _ev(uid, 1, "assistant_msg"),
+        _ev(uid, 2, "test_run", tool="Bash"),
+        _ev(uid, 3, "tool_result", payload_ref="b3"),
+    ]
+    assert infer_outcome(events, {"b3": "1 failed, traceback ..."}) == "fail"
+
+
+def test_build_digest_histograms_and_markers():
+    uid = "claude:s"
+    s = Session(session_uid=uid, flavor="claude", native_session_id="s",
+                repo="agentic-resources", cost=Cost(input_tokens=100, output_tokens=40, turns=2))
+    events = [
+        _ev(uid, 0, "user_msg"),
+        _ev(uid, 1, "edit", tool="Edit"),
+        _ev(uid, 2, "edit", tool="Write"),
+        _ev(uid, 3, "test_run", tool="Bash"),
+        _ev(uid, 4, "error"),
+        _ev(uid, 5, "assistant_msg"),
+    ]
+    d = build_digest(s, events)
+    assert d["tool_histogram"] == {"Edit": 1, "Write": 1, "Bash": 1}
+    assert d["markers"]["edits"] == 2
+    assert d["markers"]["errors"] == 1
+    assert d["markers"]["test_runs"] == 1
+    assert d["event_count"] == 6
+    assert d["cost"]["input_tokens"] == 100
+
+
+def test_analyze_writes_digest_and_sets_analyzed(tmp_path):
+    st = Store(str(tmp_path / "m.db"), str(tmp_path / "blobs"))
+    uid = Session.make_uid("claude", "s1")
+    s = Session(session_uid=uid, flavor="claude", native_session_id="s1")
+    events = [
+        SessionEvent(session_uid=uid, seq=0, kind="user_msg", payload_ref="b0"),
+        SessionEvent(session_uid=uid, seq=1, kind="assistant_msg", payload_ref="b1"),
+    ]
+    blobs = {"b0": "please help", "b1": "done"}
+    st.ingest(Normalized(session=s, events=events, blobs=blobs))
+
+    assert st.get_session(uid).is_evictable is False
+    d = analyze(st, uid)
+    assert d["outcome"] == "success"
+    assert d["first_prompt"] == "please help"
+    assert st.get_session(uid).analyzed_at is not None
+    assert st.get_session(uid).is_evictable is True  # now promoted -> evictable