fix: keep tool input when the approval request arrives before it (#1872) by threepointone · Pull Request #2391 · cloudflare/agents

threepointone · 2026-09-28T10:50:41Z

Fixes #1872. Supersedes #2021.

Problem

A tool call that needs approval could reach the approval card with input: undefined:

AI SDK 7 streams tool arguments as tool-input-delta chunks with the text in inputTextDelta. The message builder only read the older input field, so the streamed arguments were dropped.
Some custom and older streams send tool-approval-request before tool-input-available. The late tool-input-available was either ignored, or it moved the part back to input-available and hid the approval card.

Change

applyChunkToParts (agents/chat) collects the inputTextDelta text per tool part. On tool-approval-request it parses that text if the input isn't set yet. It still takes chunk.input from older emitters.
A tool-input-available that arrives after the approval request fills in the input but keeps the approval state. It only replaces input that is missing or came from the partial deltas, and it also takes the chunk's title. New exported helpers: isLateToolInputChunk, applyLateToolInput and lateToolInputForwardChunks.
AIChatAgent and Think both apply the late input, then store and send the client two chunks: the tool-input-available, followed by the part's tool-approval-request again. The AI SDK client fills in the input on the first and goes back to showing the approval on the second, and stream replay rebuilds the same state. AIChatAgent also re-persists the approval snapshot. Think's RPC stream passes both chunks to onEvent. Nothing is forwarded once the user has responded to the approval.

Tests

message-builder-approval-input.test.ts: tests covering both chunk orders, the forwarded chunk pair,, the old input field, malformed text, and not overwriting canonical input.
ai-chat late-tool-input.test.ts: the client, rebuilt from the streamed chunks, shows the approval with its input, and the persisted part carries it too.
The ai-chat test fails without the fix.

Credit to #2021 for the original reproduction and fix direction.

changeset-bot · 2026-09-28T10:50:49Z

🦋 Changeset detected

Latest commit: f41e4f2

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
agents	Patch
@cloudflare/ai-chat	Patch
@cloudflare/think	Patch
@cloudflare/agent-think	Patch

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agent-think · 2026-09-28T10:52:53Z

🟡 agents import sizes: 1 entry point grew

	Entry point	Exports	Largest gzip change	Size now
🟡	`agents/chat`	102 resized, 3 new	up to +189 B (+7.67%)	2.6 KiB

Changed exports (105)

	Import	Gzip change	Size now
🟡	`agents/chat#partAwaitsClientInteraction`	+189 B (+7.67%)	2.6 KiB
🟡	`agents/chat#unwrapChatFiberSnapshot`	+189 B (+7.6%)	2.6 KiB
🟡	`agents/chat#byteLength`	+189 B (+7.52%)	2.6 KiB
🟡	`agents/chat#MessageType`	+188 B (+7.54%)	2.6 KiB
🟡	`agents/chat#isDurableObjectResetError`	+188 B (+7.32%)	2.7 KiB
🟡	`agents/chat#resolveChatRecoveryConfig`	+188 B (+7.17%)	2.7 KiB
🟡	`agents/chat#truncateOlderMessages`	+188 B (+5.74%)	3.4 KiB
🟡	`agents/chat#toolPartHasSettledResult`	+187 B (+7.82%)	2.5 KiB
🟡	`agents/chat#originMessageIds`	+187 B (+7.7%)	2.6 KiB
🟡	`agents/chat#applyToolUpdate`	+187 B (+7.66%)	2.6 KiB
🟡	`agents/chat#createChatFiberSnapshot`	+187 B (+7.35%)	2.7 KiB
🟡	`agents/chat#runChatRecoveryExhaustion`	+187 B (+7.14%)	2.7 KiB
🟡	`agents/chat#withOriginMessageIds`	+186 B (+7.74%)	2.5 KiB
🟡	`agents/chat#STREAM_RESUME_NONE_REASONS`	+186 B (+7.74%)	2.5 KiB
🟡	`agents/chat#drainInteractionApplies`	+186 B (+7.73%)	2.5 KiB
🟡	`agents/chat#DEFAULT_CHAT_RECOVERY_TERMINAL_MESSAGE`	+186 B (+7.7%)	2.5 KiB
🟡	`agents/chat#recordChatTerminal`	+186 B (+7.65%)	2.6 KiB
🟡	`agents/chat#sendIfOpen`	+186 B (+7.6%)	2.6 KiB
🟡	`agents/chat#pausedExecutionUpdate`	+186 B (+7.59%)	2.6 KiB
🟡	`agents/chat#awaitWithDeadline`	+186 B (+7.56%)	2.6 KiB
🟡	`agents/chat#listActiveChatRecoveryIncidents`	+186 B (+7.54%)	2.6 KiB
🟡	`agents/chat#toolApprovalUpdate`	+186 B (+7.54%)	2.6 KiB
🟡	`agents/chat#buildInClauseStrings`	+186 B (+7.48%)	2.6 KiB
🟡	`agents/chat#hasIncompleteToolBatch`	+186 B (+7.46%)	2.6 KiB
🟡	`agents/chat#chatRecoveryTaskRunOptions`	+186 B (+7.44%)	2.6 KiB
🟡	`agents/chat#repairInterruptedToolParts`	+186 B (+6.93%)	2.8 KiB
🟡	`agents/chat#CHAT_RECOVERING_FLAG_TTL_MS`	+185 B (+7.83%)	2.5 KiB
🟡	`agents/chat#aiSdkRecoveryCodec`	+185 B (+7.83%)	2.5 KiB
🟡	`agents/chat#CHAT_RECOVERY_ALARM_DEBOUNCE_MS`	+185 B (+7.83%)	2.5 KiB
🟡	`agents/chat#CHAT_RECOVERY_INCIDENT_TTL_MS`	+185 B (+7.83%)	2.5 KiB
🟡	`agents/chat#DEFAULT_CHAT_RECOVERY_NO_PROGRESS_TIMEOUT_MS`	+185 B (+7.83%)	2.5 KiB
🟡	`agents/chat#partialHasSettledToolResults`	+185 B (+7.83%)	2.5 KiB
🟡	`agents/chat#CHAT_RECOVERY_STABLE_RETRY_DELAY_SECONDS`	+185 B (+7.81%)	2.5 KiB
🟡	`agents/chat#DEFAULT_CHAT_RECOVERY_MAX_OOM_RETRIES`	+185 B (+7.81%)	2.5 KiB
🟡	`agents/chat#AGENT_TOOL_STREAM_PROGRESS_BUMP_THROTTLE_MS`	+185 B (+7.81%)	2.5 KiB
🟡	`agents/chat#CHAT_STREAM_PROGRESS_CREDIT_THROTTLE_MS`	+185 B (+7.81%)	2.5 KiB
🟡	`agents/chat#DEFAULT_CHAT_RECOVERY_MAX_ATTEMPTS`	+185 B (+7.81%)	2.5 KiB
🟡	`agents/chat#MAX_BOUND_PARAMS`	+185 B (+7.81%)	2.5 KiB
🟡	`agents/chat#KV_DELETE_MAX_KEYS`	+185 B (+7.8%)	2.5 KiB
🟡	`agents/chat#ROW_MAX_BYTES`	+185 B (+7.8%)	2.5 KiB
🟡	`agents/chat#CHAT_RECOVERY_CANCELLED_REASON`	+185 B (+7.79%)	2.5 KiB
🟡	`agents/chat#CHAT_RECOVERING_KEY`	+185 B (+7.79%)	2.5 KiB
🟡	`agents/chat#CHAT_LAST_TERMINAL_KEY`	+185 B (+7.76%)	2.5 KiB
🟡	`agents/chat#ChatStreamStalledError`	+185 B (+7.67%)	2.5 KiB
🟡	`agents/chat#bumpChatRecoveryProgress`	+185 B (+7.65%)	2.5 KiB
🟡	`agents/chat#shouldCreditStreamProgress`	+185 B (+7.64%)	2.5 KiB
🟡	`agents/chat#resolveToolMergeId`	+185 B (+7.52%)	2.6 KiB
🟡	`agents/chat#classifyAgentToolChildRecovery`	+185 B (+7.43%)	2.6 KiB
🟡	`agents/chat#sweepStaleChatRecoveryIncidents`	+185 B (+7.39%)	2.6 KiB
🟡	`agents/chat#iterateWithStallWatchdog`	+185 B (+6.95%)	2.8 KiB

…and 55 more exports in the workflow artifact.

How this works

Each runtime export is bundled on its own, minified, and gzipped. Changes smaller than 100 B, or smaller than 1% and 1 KiB, are ignored. Growth over 10% or 5 KiB is marked 🔴. This report is informational and does not fail CI. The workflow artifact contains every measurement.

_{Compared c55ec800 → f41e4f2e · workflow run · reported by agent-think[bot]}

…re it (#1872) Co-authored-by: Cursor <cursoragent@cursor.com>

devin-ai-integration

Note

Newer findings are available below. Devin Review posted a newer report on this PR, in addition to the findings presented here.

Devin Review found 4 potential issues.

devin-ai-integration · 2026-09-28T11:00:08Z

StreamAccumulator

+  if (p.input !== undefined && !inputFromRawText.has(part)) return false;
+  p.input = normalizeToolInput(chunk.input).input;


🔴 Recovered approvals retain incomplete tool input

After recovery recreates an approval part, applyLateToolInput rejects the canonical input if partial deltas already populated it. provisionalInput only tracks the original part object, so the recovered approval keeps incomplete arguments.

Learn more

The provisional-input marker exists only in a WeakSet keyed by the original tool-part object. An approval part rebuilt from an early-persisted message or reconstructed stream can contain the fallback input without that marker. When the canonical tool-input-available arrives after recovery, the non-undefined fallback input triggers the first-write guard, so the corrected arguments never reach storage or the approved call. StreamAccumulator copies existing parts, and reconcileOrphanPartial preserves existing tool parts on orphan recovery.

Example: Deltas contain only {"path": before the approval request, so the fallback input becomes {}. An interruption restores the approval part from storage; a later canonical {path:"notes.txt"} cannot replace {}.

Recommended fix: Persist or reconstruct whether the approval input is provisional, or distinguish canonical input from fallback input when rebuilding approval parts. Cover an interruption between the approval request and canonical input.

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devin-ai-integration · 2026-09-28T11:00:09Z

+          const lateToolInput = isLateToolInputChunk(
+            accumulator.parts,
+            streamChunk
+          );
          const { action } = accumulator.applyChunk(streamChunk);
          this._applyActionApprovalDescriptorToParts(


🔍 Action descriptor can lag tool input

For text-only deltas, Think constructs the action descriptor before parsing the tool input at approval. Its descriptor can contain {} while the tool part holds the reconstructed arguments; check consumers of descriptor input.

Was this helpful? React with 👍 or 👎 to provide feedback.

… recovery keep it Addresses review on #2391: store and broadcast a late tool-input-available followed by the approval request again (so stream replay and live clients get the input without losing the approval card), treat an older emitter's partial delta input as provisional, and build Think's approval descriptor input from streamed delta text. Co-authored-by: Cursor <cursoragent@cursor.com>

Co-authored-by: Cursor <cursoragent@cursor.com>

devin-ai-integration

Devin Review found 2 new potential issues.

devin-ai-integration · 2026-09-28T11:39:34Z

+  if (chunk.providerExecuted != null) {
+    p.providerExecuted = chunk.providerExecuted;
+  }
+  if (chunk.providerMetadata != null) {
+    p.callProviderMetadata = chunk.providerMetadata;
+  }


🟡 Late tool input drops display title

When tool-input-available supplies a title after approval, applyLateToolInput retains the arguments but drops that title. The approval card loses its tool label if tool-input-start omitted it.

Learn more

The normal tool-input-available branch copies chunk.title to the tool part, but the new late-input branch only copies the input and provider fields. A stream that supplies its display title with the canonical input therefore loses it when approval precedes input availability.

Example: tool-input-start identifies deleteFile without a title; after approval, tool-input-available supplies title: "Delete notes.txt". The approval part retains no title.

Recommended fix: Copy chunk.title in applyLateToolInput under the same condition used by the normal available-input handler, and test both chunk orders.

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devin-ai-integration · 2026-09-28T11:39:36Z

+          if (lateToolInput) {
+            for (const forwarded of lateToolInputForwardChunks(
+              accumulator.parts,
+              streamChunk,
+              approvalRequests.get(streamChunk.toolCallId ?? "")
+            )) {
+              const chunkBody = JSON.stringify(forwarded);
+              const seq = await this._storeChunkDurably(
+                streamId,
+                forwarded,
+                chunkBody,
+                flushState
+              );
+              this._broadcastChat({
+                type: MSG_CHAT_RESPONSE,
+                id: requestId,
+                body: chunkBody,
+                done: false,
+                ...(seq !== undefined && { seq })
+              });
+              await callback.onEvent(chunkBody);
+            }
+            continue;


🔍 Think forwarding differs from described behavior

The description says Think suppresses late input. Both streaming paths instead store and broadcast it with a repeated approval request; RPC also emits both events. Confirm which stream contract consumers need.

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Co-authored-by: Cursor <cursoragent@cursor.com>

pkg-pr-new · 2026-09-28T11:49:32Z

Open in StackBlitz

agents

npm i https://pkg.pr.new/agents@2391

@cloudflare/ai-chat

npm i https://pkg.pr.new/@cloudflare/ai-chat@2391

@cloudflare/codemode

npm i https://pkg.pr.new/@cloudflare/codemode@2391

hono-agents

npm i https://pkg.pr.new/hono-agents@2391

@cloudflare/shell

npm i https://pkg.pr.new/@cloudflare/shell@2391

@cloudflare/think

npm i https://pkg.pr.new/@cloudflare/think@2391

@cloudflare/voice

npm i https://pkg.pr.new/@cloudflare/voice@2391

@cloudflare/worker-bundler

npm i https://pkg.pr.new/@cloudflare/worker-bundler@2391

commit: f41e4f2

…gine Ports four upstream changes to the legacy AIChatAgent onto AGUIChatAgent: - cloudflare#2352: clear a stale auto-continuation when the active stream finishes with stop and the tool batch is complete (finishReason read from RUN_FINISHED via the accumulator). - cloudflare#2391: a tool call whose arguments complete after its approval request refreshes the persisted approval snapshot; the event-to-chunk projection re-sends the approval request after the late tool-input-available. - cloudflare#2392: settle an approved tool call that never ran once a new turn moves past it. The pre-turn repair now also runs on submitted turns. - cloudflare#2040: reconcile reused tool-call IDs one-to-one in the AG-UI reconciler (same-call claim, per-row result merge, stale-copy drop). Test plumbing: the legacy-wire WebSocket wrapper translated each frame once per listener through a stateful projector, so a second listener lost chunks. It now translates once per frame.

threepointone added this pull request to stack #2395 September 28, 2026 10:50

threepointone changed the title ~~fix(agents,ai-chat,think): keep tool input when approval arrives before it (#1872)~~ fix: keep tool input when the approval request arrives before it (#1872) Sep 28, 2026

This was referenced Sep 28, 2026

fix: settle approved tool calls that never ran (#2382) #2392

Merged

Fix tool input reconstruction for approval requests #2021

Closed

fix(agents,ai-chat,think): keep tool input when approval arrives befo…

dfa4bad

…re it (#1872) Co-authored-by: Cursor <cursoragent@cursor.com>

threepointone force-pushed the fix/1872-approval-tool-input branch from ba804ae to dfa4bad Compare September 28, 2026 10:57

threepointone marked this pull request as ready for review September 28, 2026 10:57

devin-ai-integration Bot reviewed Sep 28, 2026

View reviewed changes

threepointone and others added 2 commits September 28, 2026 12:20

test(ai-chat): type streamed chunks in the late tool input test

f5cc126

Co-authored-by: Cursor <cursoragent@cursor.com>

devin-ai-integration Bot reviewed Sep 28, 2026

View reviewed changes

fix(agents): keep the title of a late tool-input-available

f41e4f2

Co-authored-by: Cursor <cursoragent@cursor.com>

threepointone merged commit d3fe93c into main Sep 28, 2026
16 checks passed

threepointone deleted the fix/1872-approval-tool-input branch September 28, 2026 12:29

github-actions Bot mentioned this pull request Oct 2, 2026

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fix: keep tool input when the approval request arrives before it (#1872) - #2391

fix: keep tool input when the approval request arrives before it (#1872)#2391
threepointone merged 4 commits into
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fix/1872-approval-tool-input

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		if (p.input !== undefined && !inputFromRawText.has(part)) return false;
		p.input = normalizeToolInput(chunk.input).input;

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