Resolves the issues surfaced by a self-review of the adaptive chunking
work. Tests covering each regression were added first to prove the
fix.
Critical
- Heading splitter no longer prepends breadcrumb to Content. The
breadcrumb now lives on Chunk.ContextHeader; EmbeddingContent()
combines header + content for the embedder. This restores the
End-Start == len(Content) invariant relied on by knowledge.go's
document-reconstruction path (summary generation, UI highlight) and
also eliminates the duplicate-heading regression where the section
heading appeared twice in a chunk's body.
- splitBySeparators is now genuinely recursive: when one separator
leaves a piece > ChunkSize, the next-priority separator is applied
inside that piece. Mirrors the Python reference. Without this, a
document with one paragraph break followed by a long run of
newline-separated lines could emit a single ~1950-rune chunk for
ChunkSize=300.
Medium
- SplitParentChild forces children onto the recursive tier, skipping
the per-parent profile pass (was N extra O(N) scans).
- Heuristic splitter snaps overlap start to the nearest semantic
boundary or newline instead of slicing mid-line / mid-word.
- Strategy.Split returns the legacy tier's output directly when the
whole chain rejects rather than running SplitText a second time.
Low
- ensureDefaults caps ChunkOverlap at ChunkSize/2 so pathological
configs (TokenLimit clamping ChunkSize tiny while Overlap stays
high) cannot produce ~97% overlap chunks.
- DefaultChunkOverlap docstring spells out the migration story for
KBs that stored ChunkOverlap=0.
ContextHeader plumbing
- chunker.Chunk and types.ParsedChunk gain ContextHeader plus an
EmbeddingContent() helper.
- types.Chunk gets a transient (gorm:"-") ContextHeader field so the
knowledge service can build embedding inputs as
titlePrefix + chunk.EmbeddingContent() without a DB schema change.
https://claude.ai/code/session_01XADhx6mtu2ZYW3DE9Lun6k
Claude
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