Fix client tool schemas lost after DO restart

[alexanderjacobsen]

Summary

Follow-up to #882. Client tool schemas (_lastClientTools) are stored in-memory on the Durable Object and lost on restart. This breaks autoContinueAfterToolResult when the user refreshes between a tool call and its confirmation — the continuation calls onChatMessage without tool schemas and the AI responds saying it doesn't have the tools.

Fix: Include clientTools in the CF_AGENT_TOOL_RESULT WebSocket message. The client is the source of truth for its tools and always has the current schemas, so re-sending is both simpler and more correct than server-side persistence.

Changes

• types.ts — Add optional clientTools field to CF_AGENT_TOOL_RESULT incoming message
• react.tsx — Include extractClientToolSchemas() in all CF_AGENT_TOOL_RESULT sends (sendToolOutputToServer, automatic tool resolution, addToolResultAndSendMessage)
• index.ts — Extract clientTools from tool result data and pass to onChatMessage during continuation
• tests/worker.ts — Capture clientTools from onChatMessage options for test assertions
• tests/client-tools-reconnect.test.ts — Test that tools from CF_AGENT_TOOL_RESULT are used for continuation, plus backwards compatibility test

Test plan

• All 39 existing tests pass
• New test: client tools from CF_AGENT_TOOL_RESULT are passed to onChatMessage during continuation (simulates reconnect after DO restart)
• New test: backwards compatibility — continuation works without clientTools in CF_AGENT_TOOL_RESULT
• Manual test: tool with requiresConfirmation works after page refresh

[changeset-bot]

🦋 Changeset detected

Latest commit: 14cb9b6

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

This PR includes changesets to release 2 packages

Name	Type
@cloudflare/ai-chat	Patch
agents	Patch

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commit: 14cb9b6

[whoiskatrin]

/bonk review this PR

[ask-bonk]

Review of PR #897 — Fix client tool schemas lost after DO restart

Clean, well-scoped fix for a real problem. The approach of having the client re-send tool schemas with CF_AGENT_TOOL_RESULT is the right call — the client is the source of truth and this avoids adding server-side persistence complexity. Tests cover both the happy path and backwards compatibility.

Two issues noted as inline comments below.

[ask-bonk]

Consider also updating _lastClientTools when clientTools arrives via CF_AGENT_TOOL_RESULT.

Currently clientTools is used for this specific continuation but _lastClientTools is never refreshed from it. If this continuation itself produces another tool call (multi-step tool chains), the next continuation falls back to the stale/undefined _lastClientTools — unless the client sends yet another CF_AGENT_TOOL_RESULT with clientTools.

In practice this likely works today because each tool result message from the client includes clientTools, but it would be more robust and self-documenting to also update the cache. Consider adding around line 497, before waitForStream():

// Update cached client tools so subsequent continuations use the latest schemas
if (clientTools?.length) {
  this._lastClientTools = clientTools;
}

This keeps _lastClientTools in sync regardless of how the tool result arrives, and any future code paths reading it will get the refreshed value.

[ask-bonk]

Type mismatch with ClientToolSchema: The inline type here uses Record<string, unknown> for parameters, but the canonical ClientToolSchema in index.ts:49 (and react.tsx:66) uses JSONSchema7. This means the wire-format type is looser than what the server actually expects.

This works at runtime (JSON is untyped on the wire), but TypeScript won't catch cases where a non-JSON-Schema object is passed. Two options:

1. Use JSONSchema7 here (add import type { JSONSchema7 } from "ai" to types.ts)
2. Reference ClientToolSchema from index.ts instead of duplicating the shape

Either way avoids the types drifting apart.

Nit-level — not a blocker if you'd prefer to keep types.ts free of ai imports.

[ask-bonk]

Review posted on PR #897. Here's a summary of the feedback:

Overall: The fix is well-scoped and the approach is sound — having the client re-send tool schemas with CF_AGENT_TOOL_RESULT avoids server-side persistence complexity. Tests cover both the reconnect scenario and backwards compatibility.

Two inline comments posted:

1. packages/ai-chat/src/index.ts:537 — When clientTools arrives via CF_AGENT_TOOL_RESULT, it's used for this continuation but _lastClientTools is never updated. For multi-step tool chains, the next continuation would fall back to stale/undefined _lastClientTools. Suggested adding this._lastClientTools = clientTools to keep the cache in sync.

2. packages/ai-chat/src/types.ts:129 — The inline clientTools type uses Record<string, unknown> for parameters, while the canonical ClientToolSchema uses JSONSchema7. Minor type consistency nit — not a blocker but avoids the types drifting apart.

github run

[whoiskatrin]

@alexanderjacobsen this PR should have already the fix for it? #899

give it a go

[alexanderjacobsen]

@whoiskatrin Tested #899 locally and the bug is still there

[whoiskatrin]

My bad, this is not related to streaming, just tools. LGTM