wiki: hide low-signal memories + collapse ambient AKC sessions on domain/homepage

Real usage showed two failure modes on /wiki/domains/{tag} and the homepage:

  1. Empty-transcript AKC sessions (mic-off) and synthetic E2E test memories
     competed with real knowledge in topical listings. A user hitting the
     'optics' domain page saw pages of '(no transcript)' and
     'IMG integration test — synthetic session' before finding anything useful.

  2. Every AKC voice session writes an episodic memory as provenance. At
     one session per capture burst these quickly dominate any domain page
     carrying a common tag like 'p05' or 'optics'.

This change partitions memories into three buckets on the domain and
homepage surfaces:
  - low-signal  → hidden entirely (counted in a dim sub-line)
  - AKC session → collapsed behind a single link to /wiki/activity
  - real        → rendered inline

Filter predicates are additive: a memory that's both an empty-transcript
session AND tagged as AKC lands in low-signal (priority).

Tests: 4 new tests in test_wiki_pages.py lock the partition behaviour.
All 15 pre-existing wiki tests still pass.

No schema change, no migration needed.

tests/test_wiki_pages.py

@@ -161,3 +161,103 @@ def test_memory_detail_shows_superseded_sources(tmp_data_dir):
     assert html1 is not None
     assert "superseded" in html1
     assert "auto-dedup-tier1" in html1  # audit trail shows who merged
+
+
+# -------------------------------------------------- low-signal wiki filters
+# Ambient AKC session memories and test pollution shouldn't dominate domain
+# pages / homepage counts. These tests lock the partitioning behaviour.
+
+def test_domain_page_hides_empty_transcript_sessions(tmp_data_dir):
+    """Silent-mic AKC sessions (content has '(no transcript)') are ambient
+    noise — they go into the hidden count, not the main list."""
+    _init_all()
+    # One real knowledge memory with tag "optics"
+    create_memory(
+        "knowledge",
+        "CGH null corrector supports F/1.2 asphere testing",
+        project="p05", confidence=0.9, domain_tags=["optics", "cgh"],
+    )
+    # One silent AKC session with the same tag — should NOT appear
+    create_memory(
+        "episodic",
+        "AKC voice session abc (gen-002)\nDuration: 60s, 2 captures\n"
+        "\n## Transcript\n(no transcript)\n",
+        project="p05", confidence=0.7,
+        domain_tags=["optics", "session", "akc", "voice"],
+    )
+    html = render_domain("optics")
+    assert "CGH null corrector" in html
+    # The hidden-count banner should be present
+    assert "low-signal" in html or "Ambient provenance" in html
+    # And the empty-transcript content itself is not rendered inline
+    assert "(no transcript)" not in html
+
+
+def test_domain_page_collapses_akc_session_snapshots(tmp_data_dir):
+    """AKC voice-session memories are provenance records — count them as
+    a single collapsed link, don't inline every one."""
+    _init_all()
+    for i in range(5):
+        create_memory(
+            "episodic",
+            f"AKC voice session session-{i} (gen-00{i})\nDuration: 120s, 3 captures\n"
+            f"\n## Transcript\nReal transcript number {i}",
+            project="p05", confidence=0.7,
+            domain_tags=["optics", "session", "akc", "voice"],
+        )
+    html = render_domain("optics")
+    # Inline count should mention AKC session snapshots
+    assert "AKC voice session snapshots" in html
+    # None of the session transcripts should be pasted inline on the domain
+    # page (they're provenance, linked via /wiki/activity)
+    assert "Real transcript number 0" not in html
+
+
+def test_homepage_stats_exclude_ambient_memory(tmp_data_dir):
+    """Homepage system-stats line shows real memory count, pushes ambient
+    counts into a dimmed sub-segment."""
+    _init_all()
+    # 2 real memories + 3 ambient sessions + 1 silent junk
+    create_memory("knowledge", "Real fact 1", project="p05", confidence=0.8)
+    create_memory("knowledge", "Real fact 2", project="p05", confidence=0.8)
+    for i in range(3):
+        create_memory(
+            "episodic",
+            f"AKC voice session s{i} (gen-00{i})\nReal transcript x",
+            project="p05", confidence=0.7,
+            domain_tags=["session", "akc", "voice"],
+        )
+    create_memory(
+        "episodic",
+        "AKC voice session silent (gen-099)\nDuration: 30s, 0 captures\n"
+        "\n## Transcript\n(no transcript)\n",
+        project="p05", confidence=0.7,
+        domain_tags=["session", "akc", "voice"],
+    )
+    html = render_homepage()
+    assert "3 AKC session snapshots" in html
+    assert "low-signal hidden" in html
+    # Main count reflects only real knowledge
+    assert "2 memories" in html
+
+
+def test_low_signal_predicate_catches_known_patterns():
+    from atocore.engineering.wiki import _is_low_signal_memory, _is_akc_session_memory
+    from dataclasses import dataclass
+
+    @dataclass
+    class M:
+        content: str = ""
+        domain_tags: list = None
+
+    # Explicit empty-transcript — low signal
+    assert _is_low_signal_memory(M(content="AKC voice session x\n## Transcript\n(no transcript)\n"))
+    # E2E test pollution — low signal
+    assert _is_low_signal_memory(M(content="IMG integration test — synthetic session"))
+    assert _is_low_signal_memory(M(content="synthetic AKC integration session"))
+    # Real knowledge — NOT low signal
+    assert not _is_low_signal_memory(M(content="The CGH is mounted to the fold mirror via…"))
+    # AKC session tag predicate
+    assert _is_akc_session_memory(M(content="anything", domain_tags=["session", "akc", "voice"]))
+    assert _is_akc_session_memory(M(content="AKC voice session abc"))
+    assert not _is_akc_session_memory(M(content="Real fact", domain_tags=["optics"]))