Live crash (modal-realism session): GLM double-encoded the quiz options
array as a JSON STRING inside the tool-call arguments. The bridge emitted
tool-input-available at toolcall_end — BEFORE validation runs — so the
client briefly saw the malformed quiz as a pending question and the dock
crashed in normalizeOptions ((string).map). The later tool-input-error
chunk could not revive the tree.
The old SDK gated this with InvalidToolInputError: validation ran before
the input-available chunk. The bridge now holds the part in
input-streaming until tool_execution_end and only then emits
tool-input-available (clean) or tool-input-error (invalid, structural
JSON Schema failure or the zod re-run inside execute).
Server-side behavior was already correct (the record shows the error
part + a successful model retry) — this is purely the wire-ordering hole.
Pinned in chat-flow.test.ts: the refinement-layer retry (correctAnswer
mismatch) and the exact live structural shape (string options) both
assert the invalid call never becomes input-available on the wire.
Gates: tsc, lint, build, 306/306.
The Vercel AI SDK survives only as Band D (useChat client + UIMessage
record types); @openrouter/ai-sdk-provider is uninstalled.
- src/agent/models.ts: PiEngine {model, streamFn} via createModels +
openrouterProvider subpath; thinkingLevelFor maps config effort none->off
- src/agent/lh-tool.ts: neutral LhTool (zod authoring, optional execute,
clientQuestion flag); toPiTool converts via z.toJSONSchema and re-runs
zod inside execute so refinements ride the error-result retry path
- src/server/pi/record-adapter.ts: UIMessage records -> pi Messages
(dangling tool calls get synthesized interrupted results)
- src/server/pi/ui-stream.ts: SSE bridge emitting AI-SDK-shaped chunks so
the useChat client parses unchanged (continuation id rule, question
tools never emit output, tool-input-error for bad authoring)
- teacher-agent.ts: stateless per-turn pi Agents; shouldStopAfterTurn
stops only when every question-tool call resolved cleanly (errors retry)
- chat-handler.ts: buildAgent(outgoing) factory seam (stateless doctrine);
assertValidUiMessages owns the retired SDK validation gate
- sub-agents via shared runSubagent (pi-run.ts); extraction stages stop
after a clean submit; visual-maker keeps its hand-rolled loop over
direct streamSimple calls; aborted model calls bill no usage
- tests: all model seams ported to pi-ai faux provider (scripted
FauxResponseSteps, agent factories); handleChatRequest second param
is now an agent factory
Gates: tsc, lint, build, 305/305. Live GLM smoke (disposable driver,
deleted): prober streaming + persistence, question seam, turn-2
continuation same message id, per-turn real token usage - ALL PASS.
Data wiped at the pivot (chats/graph/jobs, .gitkeeps kept).
amosblomqvist