Bug: transcript-sanitize extension never loaded — causes tool_use_id mismatch in long sessions

Error Message

FailoverError: LLM request rejected: messages.268.content.1: unexpected `tool_use_id` found in `tool_result` blocks: toolu_01YDDkR7xihJHDSiQdF8VyzV. Each `tool_result` block must have a corresponding `tool_use` block in the previous message.

Also appears as:

Embedded agent failed before reply: LLM request rejected: messages.268.content.1: unexpected `tool_use_id` found in `tool_result` blocks

Environment

• Clawdbot gateway with Anthropic provider (Claude)
• Long-running session (268+ messages)

Root Cause

The transcript-sanitize extension (dist/agents/pi-extensions/transcript-sanitize.js) exists and is designed to run repairToolUseResultPairing() on every context build via the context event hook. However, buildEmbeddedExtensionPaths() in dist/agents/pi-embedded-runner/extensions.js never includes it in the extension paths.

This means:

• repairToolUseResultPairing() runs once at session load (via sanitizeSessionHistory())
• But it does not run on subsequent context builds during the same session
• In long sessions, compaction, context pruning, and new message appends can cause tool_result blocks to become orphaned (referencing tool_use IDs that no longer exist in the preceding assistant message)
• When the Anthropic API receives these orphaned references, it rejects the entire request

Proposed Fix

In src/agents/pi-embedded-runner/extensions.ts, add transcript-sanitize to buildEmbeddedExtensionPaths():

export function buildEmbeddedExtensionPaths(params) {
    const paths = [];
    // Always include transcript-sanitize: repairs tool_use/tool_result pairing
    // on every context build, not just at session load.
    paths.push(resolvePiExtensionPath("transcript-sanitize"));
    if (resolveCompactionMode(params.cfg) === "safeguard") {
        paths.push(resolvePiExtensionPath("compaction-safeguard"));
    }
    const pruning = buildContextPruningExtension(params);
    if (pruning.additionalExtensionPaths) {
        paths.push(...pruning.additionalExtensionPaths);
    }
    return paths;
}

Workaround

Patch dist/agents/pi-embedded-runner/extensions.js directly with the above change and restart the gateway. Note: this gets overwritten on update.

Searchable Keywords

unexpected tool_use_id, tool_result blocks, Each tool_result block must have a corresponding tool_use block, FailoverError, LLM request rejected, transcript-sanitize, repairToolUseResultPairing