`_compact_old_tool_returns`, `PRIOR_TURN_NOTICE` and `turn_start` leave
`RAGCapabilityBase`, along with its `wrap_model_request` hook. The evidence
capabilities now retrieve and validate, and nothing else. Registering the compaction
capability is what rewrites a request; leaving it out sends the transcript untouched,
which was never a choice a host could make before.
The boundary is the recorded question identity rather than message shape, so a
resumption compacts what lies below the question in progress instead of switching
compaction off for the whole run. The newest earlier evidence return carries the
capsule and every other becomes a receipt, so one capsule exists by construction and
every return stays paired with its call.
Pictures of cited evidence are fetched through the capability that retrieved them and
re-attached beside the capsule with fresh labels. Ownership of a picture on the wire
requires the machine tag we write and an image directly after it, since neither
position nor prose is proof: several tools' results can arrive in one request, and a
user quoting our wording above their own picture had it removed. A picture that cannot
be fetched or decoded is emitted with neither its image nor its label.
The chat TUI and the example backend register the compactor, being multi-turn.
`client.ask`, `client.analyze` and the MCP tools do not: a single-shot question has
nothing earlier to compact.
ToolReturn.content reaches the model as a user-role message and the pictures
arrive bare, so nothing connects a figure to the chunk it came from:
BinaryContent.identifier does not survive serialization to the vision API, and
the captions in the result text correlate only by position.
Precede each picture with its position, source chunk id and self_ref.
build_binary_parts_from_results becomes build_image_content_from_results and
returns the labels interleaved with the pictures, so both attachment sites emit
them the same way.
This does not stop a model narrating retrieved pictures as user-supplied.
Measured on gemma4-26b with a single note ahead of the batch, and again with
per-image labels: it quotes the label and still says the user provided them.
The message role wins over its text.
