fix(ai): stop reparsing streamed tool input

packages/ai/src/protocols/utils/tool-stream.ts

@@ -66,7 +66,6 @@ const inputDelta = (tool: PendingTool, text: string) =>
     name: tool.name,
     namespace: tool.namespace,
     text,
-    input: Option.getOrElse(parsePartialInput(tool.input), () => ({})),
   })
 
 const toolCall = (route: string, tool: PendingTool, inputOverride?: string) => {

packages/ai/src/schema/events.ts

@@ -182,7 +182,7 @@ export const ToolInputDelta = Schema.Struct({
   name: Schema.String,
   namespace: Schema.optional(Schema.String),
   text: Schema.String,
-  /** Best-effort parse of all input fragments received through this delta. */
+  /** Optional best-effort parse supplied by adapters; native routes emit raw text until the final tool call. */
   input: Schema.optional(Schema.Unknown),
 }).annotate({ identifier: "LLM.Event.ToolInputDelta" })
 export type ToolInputDelta = Schema.Schema.Type<typeof ToolInputDelta>

packages/ai/test/provider/anthropic-messages.test.ts

@@ -1680,13 +1680,12 @@ describe("Anthropic Messages route", () => {
       expect(response.events).toEqual([
         { type: "step-start", index: 0 },
         { type: "tool-input-start", id: "call_1", name: "lookup" },
-        { type: "tool-input-delta", id: "call_1", name: "lookup", text: '{"query"', input: {} },
+        { type: "tool-input-delta", id: "call_1", name: "lookup", text: '{"query"' },
         {
           type: "tool-input-delta",
           id: "call_1",
           name: "lookup",
           text: ':"weather"}',
-          input: { query: "weather" },
         },
         { type: "tool-input-end", id: "call_1", name: "lookup", providerMetadata: undefined },
         {

packages/ai/test/provider/bedrock-converse.test.ts

@@ -822,13 +822,12 @@ describe("Bedrock Converse route", () => {
       ])
       const events = response.events.filter((event) => event.type === "tool-input-delta")
       expect(events).toEqual([
-        { type: "tool-input-delta", id: "tool_1", name: "lookup", text: '{"query"', input: {} },
+        { type: "tool-input-delta", id: "tool_1", name: "lookup", text: '{"query"' },
         {
           type: "tool-input-delta",
           id: "tool_1",
           name: "lookup",
           text: ':"weather"}',
-          input: { query: "weather" },
         },
       ])
       expect(response.events.at(-1)).toMatchObject({
@@ -916,7 +915,6 @@ describe("Bedrock Converse route", () => {
           id: "tool_1",
           name: "lookup",
           text: '{"query":"weather"}',
-          input: { query: "weather" },
         },
       ])
     }),

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

@@ -413,14 +413,12 @@ describe("Mistral Chat", () => {
           id: "Ab12Cd34E",
           name: "lookup",
           text: '{"city":',
-          input: {},
         },
         {
           type: "tool-input-delta",
           id: "Ab12Cd34E",
           name: "lookup",
           text: '"Paris"}',
-          input: { city: "Paris" },
         },
         { type: "tool-input-end", id: "Ab12Cd34E", name: "lookup", providerMetadata: undefined },
         {

packages/ai/test/provider/open-responses-lifecycle.test.ts

@@ -313,7 +313,6 @@ describe("Open Responses basic-item lifecycles", () => {
           id: "call_bc1eb4b42e70ee53",
           name: "get_weather",
           text: '{\n  "city": "Paris"\n}',
-          input: { city: "Paris" },
         },
         { type: "tool-input-end", id: "call_bc1eb4b42e70ee53", name: "get_weather", providerMetadata },
         {

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

@@ -1511,13 +1511,12 @@ describe("OpenAI Chat route", () => {
       expect(response.events).toEqual([
         { type: "step-start", index: 0 },
         { type: "tool-input-start", id: "call_1", name: "lookup", providerMetadata: undefined },
-        { type: "tool-input-delta", id: "call_1", name: "lookup", text: '{"query"', input: {} },
+        { type: "tool-input-delta", id: "call_1", name: "lookup", text: '{"query"' },
         {
           type: "tool-input-delta",
           id: "call_1",
           name: "lookup",
           text: ':"weather"}',
-          input: { query: "weather" },
         },
         { type: "tool-input-end", id: "call_1", name: "lookup", providerMetadata: undefined },
         {
@@ -1568,7 +1567,6 @@ describe("OpenAI Chat route", () => {
           id: "call_1",
           name: "lookup",
           text: '{"query":"weather"',
-          input: { query: "weather" },
         },
         {
           type: "step-finish",
@@ -1624,7 +1622,6 @@ describe("OpenAI Chat route", () => {
           id: "call_1",
           name: "lookup",
           text: '{"query":"weather"}',
-          input: { query: "weather" },
         },
         {
           type: "step-finish",
@@ -1690,7 +1687,6 @@ describe("OpenAI Chat route", () => {
           id: "call_1",
           name: "lookup",
           text: '{"query":"weather"',
-          input: { query: "weather" },
         },
       ])
     }),
@@ -1780,13 +1776,12 @@ describe("OpenAI Chat route", () => {
       expect(response.events).toEqual([
         { type: "step-start", index: 0 },
         { type: "tool-input-start", id: "call_1", name: "lookup", providerMetadata: undefined },
-        { type: "tool-input-delta", id: "call_1", name: "lookup", text: '{"query"', input: {} },
+        { type: "tool-input-delta", id: "call_1", name: "lookup", text: '{"query"' },
         {
           type: "tool-input-delta",
           id: "call_1",
           name: "lookup",
           text: ':"weather"}',
-          input: { query: "weather" },
         },
         { type: "tool-input-end", id: "call_1", name: "lookup", providerMetadata: undefined },
         {

packages/ai/test/provider/openai-responses.test.ts

@@ -4038,14 +4038,12 @@ describe("OpenAI Responses route", () => {
           id: "call_1",
           name: "lookup",
           text: '{"query"',
-          input: {},
         },
         {
           type: "tool-input-delta",
           id: "call_1",
           name: "lookup",
           text: ':"weather"}',
-          input: { query: "weather" },
         },
         {
           type: "tool-input-end",
@@ -4117,8 +4115,8 @@ describe("OpenAI Responses route", () => {
       const response = yield* LLMClient.generate(request).pipe(Effect.provide(fixedResponse(body)))
 
       expect(response.events.filter((event) => event.type === "tool-input-delta")).toEqual([
-        { type: "tool-input-delta", id: "call_1", name: "lookup", text: '{"query"', input: {} },
-        { type: "tool-input-delta", id: "call_1", name: "lookup", text: ':"weather"}', input: { query: "weather" } },
+        { type: "tool-input-delta", id: "call_1", name: "lookup", text: '{"query"' },
+        { type: "tool-input-delta", id: "call_1", name: "lookup", text: ':"weather"}' },
       ])
       expect(response.events.filter(LLMEvent.is.toolInputEnd)).toHaveLength(1)
       expect(response.events.filter(LLMEvent.is.toolCall)).toEqual([
@@ -4156,7 +4154,6 @@ describe("OpenAI Responses route", () => {
           id: "call_1",
           name: "lookup",
           text: '{"query":"weather"}',
-          input: { query: "weather" },
         },
       ])
       expect(response.events.find(LLMEvent.is.toolCall)).toMatchObject({ input: { query: "weather" } })
@@ -4217,7 +4214,6 @@ describe("OpenAI Responses route", () => {
           id: "call_1",
           name: "lookup",
           text: '{"query":"streamed"}',
-          input: { query: "streamed" },
         },
       ])
       expect(response.events.find(LLMEvent.is.toolCall)).toMatchObject({ input: { query: "final" } })

packages/ai/test/tool-stream.test.ts

@@ -23,11 +23,9 @@ describe("ToolStream", () => {
 
       expect(first.events).toEqual([
         { type: "tool-input-start", id: "call_1", name: "lookup" },
-        { type: "tool-input-delta", id: "call_1", name: "lookup", text: '{"query"', input: {} },
-      ])
-      expect(second.events).toEqual([
-        { type: "tool-input-delta", id: "call_1", name: "lookup", text: ':"weather"}', input: { query: "weather" } },
+        { type: "tool-input-delta", id: "call_1", name: "lookup", text: '{"query"' },
       ])
+      expect(second.events).toEqual([{ type: "tool-input-delta", id: "call_1", name: "lookup", text: ':"weather"}' }])
       expect(finished).toEqual({
         tools: {},
         events: [
@@ -38,7 +36,7 @@ describe("ToolStream", () => {
     }),
   )
 
-  test("exposes cumulative partial string values", () => {
+  test("streams raw deltas without reparsing cumulative input", () => {
     const result = ToolStream.appendOrStart(
       ADAPTER,
       ToolStream.empty<number>(),
@@ -53,26 +51,9 @@ describe("ToolStream", () => {
       id: "call_1",
       name: "lookup",
       text: '{"query":"wea',
-      input: { query: "wea" },
     })
   })
 
-  test("defaults partial input to an empty object when the accumulated value cannot be parsed", () => {
-    const result = ToolStream.appendOrStart(
-      ADAPTER,
-      ToolStream.empty<number>(),
-      0,
-      { id: "call_1", name: "lookup", text: "x" },
-      "missing tool",
-    )
-    if (ToolStream.isError(result)) throw result
-
-    expect(result.events).toEqual([
-      { type: "tool-input-start", id: "call_1", name: "lookup" },
-      { type: "tool-input-delta", id: "call_1", name: "lookup", text: "x", input: {} },
-    ])
-  })
-
   it.effect("keeps accumulated identity when later deltas contain empty strings", () =>
     Effect.gen(function* () {
       const first = ToolStream.appendOrStart(