fix(pipeline,api,wing): never archive a note as processed when nothing was ingested; titles do not merge sources; ties prefer the page on disk (review of #211, pass 3)

- in a wing, an ingest that writes no source page is an error: the note goes to
  raw/failed with the warnings in log.md instead of leaving the inbox as
  'processed' (model returned [], only invalid types, only clashing entities)
- the wing's source path is deterministic, so Resolve no longer redirects a
  source onto another note's page because the model gave both the same title
  ('Home'); that overwrote the hash and the text
- a batch tie between concept and entity prefers the page already on disk, so
  its update is not lost; the wing's own source page keeps its slug even when a
  foreign page shares it
- brain_pending lists an unreadable (over-cap) note with the reason instead of
  dropping it; the client filter's 4 KiB match-span limit is documented
Each has a test that fails without it (mutation-checked).

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

ingestion/internal/pipeline/wing_layout_test.go

@@ -292,3 +292,83 @@ func TestRun_AnExistingSourceEntityPairDoesNotLockTheSourceOut(t *testing.T) {
 	assert.Contains(t, read(t, dir, "wiki/homelab/sources/notes.md"), "fresh", "the source took the update")
 	assert.Contains(t, read(t, dir, "wiki/entities/notes.md"), "stale entity", "the entity is untouched")
 }
+
+// Pass 3 of #211: a note must never leave the inbox as "processed" when nothing
+// of it was written.
+func TestRun_WithAWingAnIngestThatWritesNoSourcePageIsAnError(t *testing.T) {
+	tests := []struct {
+		name  string
+		pages []RawPage
+		prep  func(t *testing.T, dir string)
+	}{
+		{"the model returned nothing", nil, nil},
+		{"only pages of a type the layout has no place for", []RawPage{{Title: "Claim", Type: "claim", Content: "## x\n\ny\n"}}, nil},
+		{"only an entity, and its slug is taken by a source", []RawPage{{Title: "S1", Type: "entity", Subtype: "tool", Content: "## Definition\n\nx\n"}},
+			func(t *testing.T, dir string) {
+				require.NoError(t, os.MkdirAll(filepath.Join(dir, "wiki/web-clip/sources"), 0o755))
+				require.NoError(t, os.WriteFile(filepath.Join(dir, "wiki/web-clip/sources/s1.md"), []byte("---\ntitle: 'S1'\n---\nx"), 0o644))
+			}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			dir := t.TempDir()
+			if tt.prep != nil {
+				tt.prep(t, dir)
+			}
+			res, err := Run(context.Background(), wingCfg("web-clip", tt.pages...), dir, "a note body", "other-note", false)
+			require.Error(t, err, "nothing was ingested; the caller must not archive it as done")
+			assert.Empty(t, res.Pages)
+			assert.Contains(t, err.Error(), "no source page")
+		})
+	}
+}
+
+func TestRun_WithAWingAnUnchangedSourceIsStillASkipNotAnError(t *testing.T) {
+	dir := t.TempDir()
+	_, err := Run(context.Background(), wingCfg("web-clip", sourceEntityConcept()...), dir, "same body", "talk", false)
+	require.NoError(t, err)
+	res, err := Run(context.Background(), wingCfg("web-clip", sourceEntityConcept()...), dir, "same body", "talk", false)
+	require.NoError(t, err)
+	assert.True(t, res.Skipped)
+}
+
+// Title resolution must not merge two different notes into one source page just
+// because the model titled both "Home": in a wing the source path is already
+// deterministic (the filename), so the title must not redirect it.
+func TestRun_WithAWingTwoNotesTheModelTitlesAlikeKeepTheirOwnSourcePages(t *testing.T) {
+	dir := t.TempDir()
+	home := func(body string) []RawPage {
+		return []RawPage{{Title: "Home", Type: "source", Subtype: "article", Content: "## Summary\n\n" + body + "\n"}}
+	}
+	_, err := Run(context.Background(), wingCfg("web-clip", home("note A text")...), dir, "body A", "note-a", false)
+	require.NoError(t, err)
+	_, err = Run(context.Background(), wingCfg("web-clip", home("note B text")...), dir, "body B", "note-b", false)
+	require.NoError(t, err)
+
+	assert.True(t, exists(dir, "wiki/web-clip/sources/note-a.md"))
+	assert.True(t, exists(dir, "wiki/web-clip/sources/note-b.md"), "note B has its own page")
+	assert.Contains(t, read(t, dir, "wiki/web-clip/sources/note-a.md"), "note A text")
+	assert.Contains(t, read(t, dir, "wiki/web-clip/sources/note-b.md"), "note B text")
+
+	res, err := Run(context.Background(), wingCfg("web-clip", home("note A text")...), dir, "body A", "note-a", false)
+	require.NoError(t, err)
+	assert.True(t, res.Skipped, "note A's hash was not overwritten by note B")
+}
+
+// Both a concept and an entity named "Foo" arrive and the CONCEPT already exists
+// on disk: the page that exists wins the tie, so its source reference is added.
+func TestRun_ABatchTieBetweenAConceptAndAnEntityPrefersThePageAlreadyOnDisk(t *testing.T) {
+	dir := t.TempDir()
+	require.NoError(t, os.MkdirAll(filepath.Join(dir, "wiki/concepts"), 0o755))
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "wiki/concepts/foo.md"),
+		[]byte("---\ntitle: 'Foo'\naliases:\n  - 'Foo'\n---\n\n## Definition\n\nexisting concept\n\n## Sources\n"), 0o644))
+	pages := []RawPage{
+		{Title: "Talk", Type: "source", Subtype: "video", Content: "## Summary\n\nx\n\n## Concepts Introduced or Reinforced\n\n[[Foo]]\n"},
+		{Title: "Foo", Type: "entity", Subtype: "tool", Content: "## Definition\n\nan entity\n"},
+		{Title: "Foo", Type: "concept", Content: "## Definition\n\na concept\n\n## Sources\n"},
+	}
+	_, err := Run(context.Background(), wingCfg("web-clip", pages...), dir, "body", "talk", false)
+	require.NoError(t, err)
+	assert.False(t, exists(dir, "wiki/entities/foo.md"))
+	assert.Contains(t, read(t, dir, "wiki/concepts/foo.md"), "talk", "the existing concept got the new source reference")
+}