Both optional capabilities read what earlier questions retrieved and cited from
the capability's state, so a host that carries only the message history hands
every run an empty record. Compaction then replaced the earlier evidence with
receipts and retained nothing, and the loss was invisible: the citations the host
already displayed were still there. It now refuses when it finds evidence from an
earlier question and no record of what that question cited.
`state_carried` reaches the optional capabilities through discovery, so the
refusal distinguishes a host that never carries state from a question that simply
cited nothing.
The documentation taught the pattern that breaks: the compose example is now
stateful and the requirement is stated where each capability is introduced.
The app's browser storage was doing exactly this, keeping only the fields the UI
reads. It now persists the whole namespace map, so the citation policy's
violations survive a reload as well as the evidence record.
`CitationPolicyCapability` makes the single enforcement decision, whatever mix of
evidence capabilities is registered: two of them must not each demand a citation for
one answer. It decides in `after_model_request`, when a response carries no tool calls
and the question can still be redirected. An explicitly ungrounded answer is a
declaration and is left alone; a question that gathered no evidence is left alone too,
read from the ledger rather than from a searches dict that a new question clears. When
the cite tool is already withdrawn the question is recorded in
`CitationPolicyState.violations` instead of pointing the model at a tool that is gone.
Registering it is the only switch. `DiscoveredEvidence` and discovery move to
`capabilities.evidence` so both optional capabilities share them, and `cite_available`
joins `evidence_tool_names` as public for the same reason.
Measured on Qwen3.6-35B over two arms of 37 questions, 29 of them unanswerable from
the corpus: explicit ungrounded declarations rose from 23 to 26, grounded answers to
unanswerable questions fell from 4 to 2, answerable questions stayed at 8 of 8, and
one redirect fired in the whole arm. Reading every answer found no invented grounding.
`EvidenceCompactionCapability` reads what the evidence capabilities recorded out of
the run registry, and `build_capsule` renders it: every cited item, grouped by the
question that last cited it, newest group first, each rendered once, with the
pictures of cited evidence and the labels that must accompany them. Discovery runs
one way and reads only, so no capability holds a reference to another and a host
running one, both or neither needs no wiring change.
Everything cited is kept whole and everything else is dropped. There is no character
budget, no picture cap and nothing to configure: a cap would only half-rescue models
that fail on long conversations regardless, and a host that needs earlier evidence
pruned can compact its own requests further.
A capability reports which of its tools produce evidence, so a cite acknowledgement
is never mistaken for one. Pictures are identified by owner, document and reference,
so one figure cited through overlapping chunks is attached once while the same
reference in another document stays a different picture.
The builder does no I/O and never sees the message history, so a picture travels with
its label and the caller fetches the bytes. Nothing reaches the wire yet.
