Chunk 2 gave search a configured set to fan out over. ask and analyze
covered one database still: the RAG capability had no way to be told which
databases a question spanned, and the analysis sandbox mounted one
document tree.
The selection travels as sources on EvidenceState, beside the filter it
scopes with, so both capabilities read it the same way. clients_covering
is the one rule that turns a selection into clients, used by search, the
sandbox mount and the cite fallback, so a question scoped to some
databases cannot search, mount or cite another. Citations carry the
database they came from, and format_for_agent names it, so the model can
attribute evidence while it answers rather than only afterwards.
The sandbox keeps one flat /documents/{id}/ namespace and resolves each id
to the client holding it, which rests on ids being UUID4. A database
copied from another breaks that, so an id held twice is refused rather
than resolved to whichever arrived last.
On the CLI, search, ask and analyze cover the configured set and label
each result with its database. Every other command works on one, named
with --database NAME (a name reaches a database behind a URI, which --db
cannot) or --db PATH, and refuses a set it cannot choose from instead of
silently reading the default database. Cold databases open together, so a
first query costs the slowest open rather than their sum.
RAGState and AnalysisState each declared the same five fields, so the generic
base could not name them: StateT was bound to BaseModel, and every access
went through cast(Any, state), a getattr by string, or a loop clearing fields
by name so it could skip the one only AnalysisState has.
EvidenceState declares them once. RAGState adds nothing, AnalysisState adds
executions and overrides begin_invocation to clear them. StateT binds to
EvidenceState, which removes all ten casts and both state-shape getattrs; the
three getattr(ctx.deps, "state") probes stay, since those check a
host-supplied object rather than our own state.
discover_evidence reached into capability.state for two fields. It now asks
through evidence_record() and citation_index(), alongside the
evidence_tool_names() and cite_available accessors it already used. The eval
runner's _RagLikeState protocol and the chat app's getattr reads described
this shape from outside and are gone.
Compatibility is semantic JSON-object equivalence, not bytes: field names and
nesting are unchanged, so a dict stored by 0.75.0 loads and re-dumps equal,
but deriving from a shared base reorders AnalysisState's keys. Nothing
serializes, hashes or string-compares this state — every carry point
re-validates by key.
The guard accepted one carried record as covering the whole request, so a host
retaining only the RAG namespace had its earlier analysis evidence replaced by
receipts and lost, with the RAG record making the loss look accounted for.
Each capability is now judged on its own, and only when its own evidence is at
stake: another capability's record says nothing about this one's, and requiring
every record would stop a host that registers both capabilities and only ever
uses one.
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.
Resumption was inferred from the transcript, and no shape says it. A missing
prompt is how UI adapters ask their first question as much as how pydantic-ai
resumes one, so every AG-UI host failed on its first message. Reading the tail
instead moved the error rather than fixing it: a settled structured answer ends
with an output tool's return, indistinguishable from results delivered to a
question still in progress, so following questions inherited the first one's
identity.
`CapabilityEvidenceRecord.in_progress` is now the authority. `begin_question`
sets it, `after_run` clears it unless the run is only pausing for deferred work,
and a run that raised never reaches `after_run`, which is what leaves an
interrupted question claimable. The history is consulted only to catch a host
that dropped the state of a question the model is unmistakably still owed.
A request can carry several of this capability's returns — a model can call search
twice in one response — and the carrier was identified by message alone, so each of
them received the whole capsule. It is selected by message and part now, so exactly
one carries it however many share the request.
The chat TUI passed its persisted state into the run, so tool synchronisation mutated
it in place while the message history was promoted only on success. A cancelled or
failed run therefore kept the evidence the tools had recorded and discarded the
messages that justified it, and the next question derived its identity from the
shorter history: behind the recorded epoch, refused as non-append-only, the
conversation unusable until cleared. The run gets a copy, promoted with the messages
or not at all.
Five decorators had been left attached to a helper by an earlier extraction, which
pytest does not collect, so the resume case they carried was silently untested. The
wire test covers both resume shapes again, no prompt and deferred results.
`_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.
