Closes #272
What
With output_type set, ai.stream() (and Agent.run()) now emit an ai.events.PartialOutput event after each text delta that changes the parse of the accumulated JSON. The latest snapshot is also available as stream.partial_output.
PartialOutput.valueis a plaindict— the best-effort parse of the JSON so far, deliberately unvalidated.Stream.outputremains the validated contract once the stream ends.- Parsing uses
json-repairwithstream_stable=True: truncated values stay verbatim strings instead of being creatively repaired mid-stream, and successive snapshots only grow toward the final object. - Emission lives in
Stream.__anext__behind an internal queue, so message stamping and telemetry apply to partials exactly like provider events.
Why json-repair
New core dependency (json-repair==0.*, matching the repo's major-pin convention). Justification: MIT, zero required dependencies, ~50KB wheel, pure Python ≥3.10 — and its stream_stable mode is purpose-built for this exact problem. It also gives the SDK a battle-tested repair primitive for future output-repair work. Without it we'd be maintaining a hand-rolled tolerant JSON parser (~150 lines) with a long truncation edge-case tail.
Behavior notes
- Streams without
output_typenever emit partials; no changes for existing consumers that don't opt in - Dangling keys without values are dropped; keys with a colon but no value complete with
\\(pinned by tests) - Agent runs forward model stream events unchanged, so
AgentStreamconsumers get partials for free; the UI adapter's match ignores unknown kinds safely
Validation
uv run pytest: 766 passed — new tests cover the snapshot sequence vs deltas, dedupe of unchanged parses,partial_outputtracking, pinnedjson_repairtruncation behaviors (so a minor bump can't silently change semantics), no-partial-without-output_type, and agent-stream forwardingruff format --check/ruff check: cleanmypy: identical to baseline on main (pre-existing errors only)ty check: clean
Activity
9
socket-security[bot]2mo agoReview the following changes in direct dependencies. Learn more about Socket for GitHub.
| Diff | Package | Supply Chain Security | Vulnerability | Quality | Maintenance | License |
|---|---|---|---|---|---|---|
| pypi/json-repair@0.63.3 |
jaygupta172mo agoCould a maintainer add the feature label? (External PRs can't set labels — same as #271.) The Vercel deploy check also needs collaborator status, so it'll stay red on this fork PR; the Python 3.12–3.15 test matrix is what matters here.
jaygupta172mo agohey folks quick ping on #271 and #273 when you get a sec, been open since Aug 26. both are mergeable and green across 3.12-3.15 and Socket. the two reds are just fork perms (Vercel needs collaborator auth and changelog-label needs the feature tag which I can't set). happy to jump on any feedback fast. thanks!
jaygupta172mo agoRebased onto latest main and ported onto the new _MessageHydrator: dropped my copy of _aggregate_event, the parse step now reads the hydrator message, telemetry fields come from the hydrator. Ruff, mypy, ty, pytest (188 across models/agents/types), and uv lock check all green locally. Same two reds as #271 need a maintainer (feature label + Vercel auth).
jaygupta172mo agoRebased onto latest main. I took the Vercel agent suggestion: synthetic PartialOutput events now carry the live message instead of the dummy default, with a test pinning it. Ruff, ty, mypy (src), and pytest are green locally.
The two reds still need a maintainer: the feature label and Vercel auth.
@jaygupta17 is attempting to deploy a commit to the Vercel Labs Team on Vercel.
A member of the Team first needs to authorize it.