fix: migrate Gemini Interactions emitter to SDK 2.x event protocol (#277)#279
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The Interactions mock emitter produced the SDK 1.x streamed event shapes (interaction.start/complete, content.start/delta/stop), which have zero event_type overlap with the SDK 2.x adapter (@google/genai v2 'Interactions breaking changes, May 2026'). A v2 consumer hit its switch default for every event and rendered an empty assistant message. - Rewrite the three SSE builders to emit interaction.created/completed and step.start/delta/stop. Tool-call identity (id/name) now lives on step.start with an empty arguments placeholder; arguments stream as a dedicated arguments_delta carrying a JSON-string fragment (valid JSON by step.stop). - Count step.delta (not content.delta) for truncateAfterChunks budget. - Teach collapseGeminiInteractionsSSE the 2.x shapes (step.start identity + arguments_delta assembly, nested thought_summary), keeping 1.x parsing for backward compatibility with previously recorded fixtures. - Update unit/integration/collapse tests and drift SDK shapes to 2.x; add round-trip and legacy backward-compat coverage. Closes CopilotKit#277
Address review findings on the SDK 2.x migration: - Flag assembled arguments_delta fragments that don't concatenate into valid JSON by step.stop via droppedChunks/firstDroppedSample, instead of silently writing a corrupt tool call into a recorded fixture. - Preserve the identity of a function_call step.start that arrives without an index by minting a synthetic key (matches the sibling collapsers) rather than dropping it silently. - Reword the emitter's arguments_delta comment: the mock emits one whole fragment (a valid degenerate case), it does not itself concatenate. - Add tests: multiple/interleaved tool calls collapse in step-index order, emitter assigns sequential step indices, invalid-JSON assembly is flagged, and an index-less function_call step.start keeps its identity.
- Streaming builders: malformed tool-call arguments degrade to a valid '{}'
arguments_delta fragment and emit a warning.
- Tool-call and content+tools streams: assert usage propagates and the
terminal status is requires_action on interaction.completed (unit + e2e).
- Collapser: pin the ordering behavior when an arguments_delta arrives before
its step.start — the early fragment is flagged via droppedChunks rather than
mis-attributed, and the call still surfaces with empty args.
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Summary
Migrates the Gemini Interactions mock emitter from the SDK 1.x streamed-event format to SDK 2.x (the "Interactions breaking changes, May 2026" shapes in
@google/genaiv2). Previously the emitter producedinteraction.start/interaction.complete+content.start/content.delta/content.stop, which have zeroevent_typeoverlap with the v2 adapter — a migrated consumer hit itsswitchdefault for every event and rendered an empty assistant message.Closes #277.
What changed
src/gemini-interactions.ts— rewrote the three SSE builders:interaction.start/complete→interaction.created/completed(id stays populated on both; status text→completed, tool calls→requires_action).content.start/delta/stop→step.start { step: { type: "model_output" } }/step.delta { delta: { type: "text", text } }/step.stop.id,name) now lives onstep.startwith anarguments: {}placeholder; arguments stream asstep.delta { delta: { type: "arguments_delta", arguments: "<json-string fragment>" } }, valid JSON bystep.stop.writeGeminiInteractionsSSEStreamnow countsstep.delta(notcontent.delta) for thetruncateAfterChunksbudget.src/stream-collapse.ts—collapseGeminiInteractionsSSEnow parses 2.x events (assemble tool calls fromstep.startidentity +arguments_deltastring fragments keyed by index; nestedthought_summary.content.text), while keeping 1.x parsing for previously recorded fixtures. Hardened against silent data loss: malformed assembled args and index-less / uncorrelatedstep.start/arguments_deltaare flagged viadroppedChunks/firstDroppedSamplerather than written silently.Tests + drift baseline — updated unit/integration/collapse tests and
src/__tests__/drift/sdk-shapes.tsto 2.x; added round-trip, multiple/interleaved tool calls, ordering, malformed-args, usage/status, and 1.x backward-compat coverage.Verification
grep -E 'event_type: "(step|interaction\.created|interaction\.completed)' dist/gemini-interactions.jsmatches after build (20 hits, 0 legacy shapes remain). Full suite: 4026 passing, prettier + eslint clean.
This unblocks re-enabling the
stateful-interactionse2e test in TanStack/ai#781 once aimock is bumped.Notes / scope
outputs: [{ type: "function_call", ... }]) were intentionally left unchanged — the issue scoped the wire-format mismatch to the streamed SSE emitter.function_callwhosestep.startcarries an empty{}placeholder but never receives anarguments_deltafinalizes to"{}". On the wire that is byte-identical to a legitimately empty-args call, so flagging it would false-positive on every legitimate empty-args call.🤖 Generated with Claude Code