perf: incremental profile rebuilds — fold new gists instead of re-digesting all

The profile pass map-reduced every session gist (~851) on every consolidation
firing — the biggest redundant-work and MI50-heat source left after the eras fix.
Now: skip when nothing's new, fold only the gists added since last build into the
existing profile, and full-rebuild only when there's no profile, too much has
accumulated to fold safely (>FOLD_LIMIT), on a periodic cadence (anti-drift), or
when forced.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyra/profile.py

@@ -26,6 +26,19 @@ Organize under these headings: Poker Style, Leaks & Tendencies, Mental Game, \
 Personal Context, Working With Brian. Keep it tight — bullets, no fluff, no \
 repetition. Resolve contradictions toward the more recent/frequent signal."""
 
+_FOLD_PROMPT = """Update Brian's existing profile with new facts from his most \
+recent sessions. Keep the same headings (Poker Style, Leaks & Tendencies, Mental \
+Game, Personal Context, Working With Brian). Integrate genuinely new durable facts, \
+strengthen or revise existing bullets where the new sessions confirm or contradict \
+them (favor the more recent signal), and drop nothing that's still true. Keep it \
+tight — bullets, no fluff, no repetition. Return the full updated profile."""
+
+# A long gap (consolidation hasn't run in ages) folds too much at once to trust the
+# delta path; rebuild from scratch instead. And cross every Nth session do a full
+# rebuild regardless, so accumulated small folds can't fossilize stale facts.
+FOLD_LIMIT = 25
+FULL_REBUILD_EVERY = 100
+
 
 def _batch_texts(texts: list[str], budget: int) -> list[str]:
     """Group texts into joined blocks under `budget` chars."""
@@ -49,26 +62,57 @@ def _call(prompt: str, body: str, backend: Backend) -> str:
     return llm.complete(messages, backend=backend)
 
 
-def rebuild_profile(backend: Backend | None = None) -> str | None:
+def _map_reduce(gists: list[str], backend: Backend) -> str:
-    """Re-derive the profile from all current session gists and store it."""
+    """MAP: extract facts from batches of gists. REDUCE: fold to one fact list."""
+    partials = [_call(_MAP_PROMPT, b, backend) for b in _batch_texts(gists, BATCH_CHARS)]
+    while len(partials) > 1:
+        partials = [_call(_REDUCE_PROMPT, g, backend) for g in _batch_texts(partials, BATCH_CHARS)]
+    return partials[0]
+
+
+def _full_rebuild(gists: list[str], backend: Backend) -> str:
+    """Re-derive the whole profile from every gist (the expensive path)."""
+    profile = _map_reduce(gists, backend)
+    memory.set_profile(profile, len(gists))
+    logbus.log("info", "profile rebuilt", sessions=len(gists), chars=len(profile))
+    return profile
+
+
+def _fold(existing: str, new_gists: list[str], total: int, backend: Backend) -> str:
+    """Fold only the new session gists into the existing profile (the cheap path)."""
+    facts = _map_reduce(new_gists, backend)
+    body = f"EXISTING PROFILE:\n{existing}\n\nNEW FACTS FROM RECENT SESSIONS:\n{facts}"
+    profile = _call(_FOLD_PROMPT, body, backend)
+    memory.set_profile(profile, total)
+    logbus.log("info", "profile folded", added=len(new_gists), total=total, chars=len(profile))
+    return profile
+
+
+def rebuild_profile(backend: Backend | None = None, force: bool = False) -> str | None:
+    """Derive Brian's profile from session gists. Incremental by default: if a profile
+    already exists, fold only the gists added since it was last built instead of
+    re-digesting all of them every consolidation pass (the old behavior re-read ~851
+    sessions each time — the biggest redundant-work / MI50-heat source). Falls back to
+    a full rebuild when there's no profile yet, too much has accumulated to fold safely,
+    on a periodic cadence (anti-drift), or when `force=True`."""
     backend = backend or config.load().summary_backend
     summaries = memory.list_summaries()
     if not summaries:
         return None
+    total = len(summaries)
+    existing = memory.get_profile()
+    covered = memory.profile_sessions_covered()
 
-    # MAP: extract facts from batches of gists.
+    if existing and not force and 0 < covered <= total:
-    blocks = _batch_texts([s.content for s in summaries], BATCH_CHARS)
+        new = total - covered
-    partials = [_call(_MAP_PROMPT, b, backend) for b in blocks]
+        if new == 0:
-    logbus.log("info", "profile map done", batches=len(partials), sessions=len(summaries))
+            logbus.log("info", "profile unchanged", sessions=total)
+            return existing  # nothing new since last build — skip entirely
+        crosses_cadence = total // FULL_REBUILD_EVERY != covered // FULL_REBUILD_EVERY
+        if new <= FOLD_LIMIT and not crosses_cadence:
+            return _fold(existing, [s.content for s in summaries[covered:]], total, backend)
 
-    # REDUCE: fold partials together until one remains.
+    return _full_rebuild([s.content for s in summaries], backend)
-    while len(partials) > 1:
-        partials = [_call(_REDUCE_PROMPT, g, backend) for g in _batch_texts(partials, BATCH_CHARS)]
-    profile = partials[0]
-
-    memory.set_profile(profile, len(summaries))
-    logbus.log("info", "profile rebuilt", sessions=len(summaries), chars=len(profile))
-    return profile
 
 
 def main() -> int:

tests/test_profile.py

@@ -0,0 +1,84 @@
+"""Profile derivation: fold only new gists into the existing profile (incremental).
+
+The old pass re-digested all ~851 gists every consolidation; this checks the cheap
+delta path fires in steady state and the full rebuild fires only when it should.
+"""
+from __future__ import annotations
+
+import importlib
+
+import pytest
+
+from lyra.memory import Summary
+
+
+@pytest.fixture
+def prof(monkeypatch):
+    import lyra.profile as profile
+    importlib.reload(profile)
+    return profile
+
+
+def _wire(profile, monkeypatch, gists, covered, existing):
+    """Stub memory + the LLM passes; record which path ran."""
+    state = {"stored_content": existing, "stored_covered": covered, "calls": []}
+
+    monkeypatch.setattr(profile.memory, "list_summaries",
+                        lambda: [Summary(f"s{i}", g, i, "t") for i, g in enumerate(gists)])
+    monkeypatch.setattr(profile.memory, "get_profile", lambda: state["stored_content"])
+    monkeypatch.setattr(profile.memory, "profile_sessions_covered", lambda: state["stored_covered"])
+
+    def set_profile(content, sessions_covered, profile_id="self"):
+        state["stored_content"], state["stored_covered"] = content, sessions_covered
+    monkeypatch.setattr(profile.memory, "set_profile", set_profile)
+
+    monkeypatch.setattr(profile, "_map_reduce",
+                        lambda gists, backend: state["calls"].append(("map_reduce", len(gists))) or "facts")
+    monkeypatch.setattr(profile, "_call",
+                        lambda prompt, body, backend: state["calls"].append(("fold",)) or "folded profile")
+    return state
+
+
+def test_no_profile_yet_does_full_rebuild(prof, monkeypatch):
+    state = _wire(prof, monkeypatch, gists=["a", "b", "c"], covered=0, existing=None)
+    out = prof.rebuild_profile(backend="local")
+    assert state["calls"] == [("map_reduce", 3)]          # mapped all three gists
+    assert out == "facts" and state["stored_covered"] == 3
+
+
+def test_unchanged_skips_entirely(prof, monkeypatch):
+    state = _wire(prof, monkeypatch, gists=["a", "b"], covered=2, existing="old profile")
+    out = prof.rebuild_profile(backend="local")
+    assert state["calls"] == []                            # no LLM work at all
+    assert out == "old profile"
+
+
+def test_small_delta_folds_only_new(prof, monkeypatch):
+    state = _wire(prof, monkeypatch, gists=["a", "b", "c", "d"], covered=2, existing="old profile")
+    out = prof.rebuild_profile(backend="local")
+    assert state["calls"] == [("map_reduce", 2), ("fold",)]  # mapped just the 2 new, then folded
+    assert out == "folded profile" and state["stored_covered"] == 4
+
+
+def test_force_does_full_rebuild(prof, monkeypatch):
+    state = _wire(prof, monkeypatch, gists=["a", "b", "c"], covered=3, existing="old profile")
+    out = prof.rebuild_profile(backend="local", force=True)
+    assert state["calls"] == [("map_reduce", 3)]          # ignored the up-to-date profile
+    assert out == "facts"
+
+
+def test_big_gap_falls_back_to_full_rebuild(prof, monkeypatch):
+    gists = [str(i) for i in range(40)]                    # 30 new > FOLD_LIMIT
+    state = _wire(prof, monkeypatch, gists=gists, covered=10, existing="old profile")
+    out = prof.rebuild_profile(backend="local")
+    assert state["calls"] == [("map_reduce", 40)]          # full rebuild, not a giant fold
+    assert out == "facts"
+
+
+def test_crossing_cadence_forces_full_rebuild(prof, monkeypatch):
+    # covered=98, total=102 is a tiny delta, but it crosses the 100-session boundary.
+    gists = [str(i) for i in range(102)]
+    state = _wire(prof, monkeypatch, gists=gists, covered=98, existing="old profile")
+    out = prof.rebuild_profile(backend="local")
+    assert state["calls"] == [("map_reduce", 102)]         # anti-drift full rebuild
+    assert out == "facts"