feat: associative cognition — thoughts arise from spreading activation, not a re-read bio

Replaces the thought loop's grist (recent-convo + her own saved narrative, the
feedback-loop attractor) with a model of how a thought actually arises:

  seed (salience-weighted: a recent moment / resurfaced memory / feed item)
   -> spreading activation: embed the seed, let it light up associatively-near
      material across ALL her stores (conversations, gists, her own journal/
      thoughts), blended by relevance + recency + noise; optional 2nd hop for leaps
   -> her self-narrative stays the LENS (supplied as interiority), not the input
   -> the thought is generated from what lit up, routed through a faculty
      (notice / connect / abstract / project / feel)
   -> journaled + embedded, so it can light up in future cycles

This breaks the feedback loop structurally: the narrative is no longer reread and
paraphrased each cycle; grist is genuinely associative and varied; and her past
thoughts re-activate (continuity without calcification).

- lyra/cognition.py (new): spontaneous_seed, activate (spreading activation),
  constellation_block, faculties.
- memory.py: journal entries now embedded; recall_journal(); backfill_journal_embeddings()
  (ran once: 341 past entries embedded so her history is associatively retrievable).
- thoughts.think(): new-thread mode now uses the associative engine; dropped _grist().
- tests: test_cognition.py (recall_journal ranking, activation, seeding) + fixture
  reloads cognition. Suite 72 green, ruff clean.

Honest scope: this fixes the mechanism (how thoughts arise). The residual
"be useful for Brian" voice drift is the separate model/fine-tune problem.

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

tests/test_cognition.py

@@ -0,0 +1,83 @@
+"""Associative cognition: embedding-based recall over her journal + spreading
+activation (what 'lights up' from a seed) + spontaneous seeding."""
+from __future__ import annotations
+
+import importlib
+
+import pytest
+
+
+def _fake_embed(texts):
+    """Content-sensitive embeddings: same words -> same vector, overlap -> closer.
+    (The shared test stub returns a constant, which would make all cosines equal.)"""
+    out = []
+    for t in texts:
+        v = [0.0] * 64
+        for w in t.lower().split():
+            v[hash(w) % 64] += 1.0
+        out.append(v if any(v) else [1e-6] * 64)
+    return out
+
+
+@pytest.fixture
+def lyra(tmp_path, monkeypatch):
+    monkeypatch.setenv("LYRA_DB_PATH", str(tmp_path / "test.db"))
+    from lyra import llm
+    monkeypatch.setattr(llm, "embed", _fake_embed)
+    import lyra.memory as memory
+    importlib.reload(memory)
+    import lyra.self_state as self_state
+    importlib.reload(self_state)
+    import lyra.cognition as cognition
+    importlib.reload(cognition)
+    return memory, cognition
+
+
+def test_recall_journal_ranks_by_meaning(lyra):
+    memory, _ = lyra
+    memory.add_journal_entry("thought", "poker tilt control discipline at the table")
+    memory.add_journal_entry("thought", "the quiet stillness between our conversations")
+    memory.add_journal_entry("thought", "usb drive hardware windows formatting")
+    hits = memory.recall_journal("poker tilt discipline", k=3)
+    assert hits and "poker" in hits[0]["content"]          # the on-topic entry ranks first
+    assert "score" in hits[0] and "embedding" not in hits[0]
+
+
+def test_recall_journal_skips_unembedded_rows(lyra):
+    memory, _ = lyra
+    # simulate a pre-embedding-era entry (NULL embedding) — must be skipped, not crash
+    conn = memory._connection()
+    with conn:
+        conn.execute("INSERT INTO journal (created_at, kind, content) VALUES ('2020-01-01','thought','old')")
+    memory.add_journal_entry("thought", "fresh embedded poker thought")
+    hits = memory.recall_journal("poker", k=5)
+    assert all(h["content"] != "old" for h in hits)
+
+
+def test_activate_lights_up_related_not_unrelated(lyra):
+    memory, cognition = lyra
+    memory.ensure_session("s1")
+    memory.remember("s1", "user", "I keep tilting when I'm card dead at poker")
+    memory.add_journal_entry("thought", "tilt is really about ego and discipline")
+    memory.add_journal_entry("thought", "spring gardening soil and seedlings")
+    items = cognition.activate("poker tilt discipline", k=4, hops=1)
+    assert items and all("text" in i and "source" in i for i in items)
+    joined = " ".join(i["text"] for i in items)
+    assert "tilt" in joined                                  # related material surfaced
+
+
+def test_spontaneous_seed_fallback_then_real(lyra):
+    memory, cognition = lyra
+    s = cognition.spontaneous_seed()                         # empty DB -> wander fallback
+    assert s["text"] and s["source"]
+    memory.ensure_session("s1")
+    memory.remember("s1", "user", "been thinking about impermanence lately")
+    s2 = cognition.spontaneous_seed()                        # now has material to draw on
+    assert isinstance(s2["text"], str) and s2["text"] and s2["source"]
+
+
+def test_constellation_block_handles_empty(lyra):
+    _, cognition = lyra
+    assert "quiet" in cognition.constellation_block([]).lower()
+    block = cognition.constellation_block([{"source": "conversation", "text": "hi there"}])
+    assert "hi there" in block