fix(ai): raise typed errors for failed finishes (#47688)

packages/ai/src/protocols/gemini.ts

@@ -639,6 +639,14 @@ const step = (state: ParserState, event: GeminiEvent) => {
       : state.usage,
   }
   const candidate = event.candidates?.[0]
+  if (candidate?.finishReason && mapFinishReason(candidate.finishReason, state.hasToolCalls) === "error")
+    return Effect.fail(
+      ProviderShared.eventError(
+        state.route,
+        `Gemini stopped with ${candidate.finishReason}`,
+        ProviderShared.encodeJson(event),
+      ),
+    )
   if (!candidate?.content)
     return Effect.succeed([
       { ...nextState, finishReason: candidate?.finishReason ?? nextState.finishReason },

packages/ai/src/protocols/mistral-chat.ts

@@ -9,6 +9,8 @@ import {
   AIError,
   InvalidProviderOutputError,
   LLMEvent,
+  ProviderInternalError,
+  UnknownProviderError,
   Usage,
   type FinishReasonDetails,
   type LLMRequest,
@@ -700,6 +702,16 @@ const step = Effect.fn("MistralChat.step")(function* (state: ParserState, event:
     normalized: mapFinishReason(choice.finish_reason),
     raw: choice.finish_reason,
   }
+  if (finishReason.normalized === "error") {
+    const details = {
+      message: `Mistral Chat stopped with ${finishReason.raw}`,
+      body: ProviderShared.encodeJson(event),
+    }
+    return yield* new AIError({
+      reason:
+        finishReason.raw === "network_error" ? new ProviderInternalError(details) : new UnknownProviderError(details),
+    })
+  }
   const incomplete = finishReason.normalized === "length" || finishReason.normalized === "content-filter"
   if (!incomplete && Object.keys(withTools.pendingTools).length > 0)
     return yield* ProviderShared.eventError(

packages/ai/test/provider/gemini.test.ts

@@ -1643,19 +1643,14 @@ describe("Gemini route", () => {
     }),
   )
 
-  it.effect("maps current blocking and invalid-output finish reasons", () =>
+  it.effect("preserves blocking finishes and rejects invalid-output finish reasons", () =>
     Effect.gen(function* () {
       const reasons = [
         ["MODEL_ARMOR", "content-filter"],
         ["IMAGE_PROHIBITED_CONTENT", "content-filter"],
         ["IMAGE_RECITATION", "content-filter"],
         ["LANGUAGE", "content-filter"],
-        ["UNEXPECTED_TOOL_CALL", "error"],
-        ["NO_IMAGE", "error"],
         ["IMAGE_OTHER", "unknown"],
-        ["TOO_MANY_TOOL_CALLS", "error"],
-        ["MISSING_THOUGHT_SIGNATURE", "error"],
-        ["MALFORMED_RESPONSE", "error"],
       ] as const
 
       for (const [raw, normalized] of reasons) {
@@ -1666,6 +1661,26 @@ describe("Gemini route", () => {
         )
         expect(response.finishReason).toEqual({ normalized, raw })
       }
+
+      for (const raw of [
+        "MALFORMED_FUNCTION_CALL",
+        "UNEXPECTED_TOOL_CALL",
+        "NO_IMAGE",
+        "TOO_MANY_TOOL_CALLS",
+        "MISSING_THOUGHT_SIGNATURE",
+        "MALFORMED_RESPONSE",
+      ]) {
+        const event = { candidates: [{ finishReason: raw, finishMessage: "Provider detail" }], responseId: "failure" }
+        const error = yield* LLMClient.generate(request).pipe(
+          Effect.provide(fixedResponse(sseEvents(event))),
+          Effect.flip,
+        )
+        expect(error).toMatchObject({
+          _tag: "AI.Error",
+          reason: { _tag: "InvalidProviderOutput", body: JSON.stringify(event), http: { status: 200 } },
+          message: `Gemini stopped with ${raw}`,
+        })
+      }
     }),
   )
 

packages/ai/test/provider/mistral-chat.test.ts

@@ -600,7 +600,6 @@ describe("Mistral Chat", () => {
         ["stop", "stop"],
         ["model_length", "length"],
         ["tool_calls", "tool-calls"],
-        ["error", "error"],
         ["future_reason", "unknown"],
       ] as const) {
         const response = yield* LLMClient.generate(request).pipe(
@@ -609,6 +608,22 @@ describe("Mistral Chat", () => {
         expect(response.finishReason).toEqual({ normalized, raw })
       }
 
+      for (const [raw, tag] of [
+        ["error", "UnknownProvider"],
+        ["network_error", "ProviderInternal"],
+      ] as const) {
+        const event = { ...chunk({}, raw), diagnostics: { trace: "failure" } }
+        const error = yield* LLMClient.generate(request).pipe(
+          Effect.provide(fixedResponse(sseEvents(event))),
+          Effect.flip,
+        )
+        expect(error).toMatchObject({
+          _tag: "AI.Error",
+          reason: { _tag: tag, body: JSON.stringify(event), http: { status: 200 } },
+          message: `Mistral Chat stopped with ${raw}`,
+        })
+      }
+
       const truncated = yield* LLMClient.generate(request).pipe(
         Effect.provide(
           fixedResponse(