#6687: fix(session-repair): strip malformed tool_use blocks to prevent permanent session corruption

## Summary - Strips malformed `tool_use`/`toolCall`/`functionCall` blocks from assistant messages BEFORE the existing pairing repair runs - Adds `droppedMalformedToolUseCount` to the repair report for observability - Prevents creating synthetic error results for blocks that were never valid tool calls ## Problem When tool calls are interrupted (by error, timeout, content filtering, or process termination), sessions become **permanently corrupted**. Every subsequent API request fails with: - `unexpected tool_use_id found in tool_result blocks` - `tool result's tool id not found (2013)` **Root cause:** The existing `extractToolCallsFromAssistant()` skips malformed blocks (missing id) but **leaves them in the message content**. The blocks remain in the transcript, causing API rejections. ## Solution Add a pre-processing step that strips malformed tool_use blocks before the pairing repair runs: **Malformed conditions detected:** - Missing or empty `id` field (tool call wasn't fully initialized) - Has `partialJson` field present (Anthropic SDK streaming artifact) - uses property presence check (`"partialJson" in rec`) to catch regardless of value - Has `partial` field set to `true` (generic streaming indicator) - Has `incomplete` field set to `true` (OpenAI-style indicator) **Type variants supported (via shared `TOOL_BLOCK_TYPES` Set):** - camelCase: `toolCall`, `toolUse`, `functionCall` - snake_case: `tool_use`, `function_call` Both `isValidToolUseBlock` and `extractToolCallsFromAssistant` use the same `TOOL_BLOCK_TYPES` Set to ensure consistent handling across validation and extraction. The `name` field is intentionally NOT required - `extractToolCallsFromAssistant` already handles missing names gracefully by defaulting to `undefined`. ### Design decisions - **Shared constant:** `TOOL_BLOCK_TYPES` is a Set used by both functions to ensure consistency. - **Property presence vs value check:** For `partialJson`, we use `"partialJson" in rec` rather than `!== undefined` because the mere presence of this field (even if explicitly `undefined`) indicates a streaming artifact. - **Strict boolean checks for partial/incomplete:** We use `=== true` rather than truthy checks to avoid false positives from falsy values like `0`, `""`, or `null` which don't indicate a partial tool call. - **Expanded logging:** All non-zero repair counters are now logged (malformed stripped, orphans dropped, duplicates dropped, synthetic results added) for easier debugging. ## Test plan - [x] Added comprehensive tests for malformed block detection - [x] Existing tests pass (`pnpm test src/agents/session-transcript-repair.test.ts`) - [x] Full test suite passes (`pnpm test`) - [x] Lint passes (`pnpm lint`) Fixes #5497, #5481, #5430, #5518 🤖 Generated with [Claude Code](https://claude.com/claude-code) <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR hardens session transcript repair by stripping malformed assistant tool blocks (e.g., missing/empty `id` or streaming artifacts like `partialJson`, `partial: true`, `incomplete: true`) before the existing tool-call/tool-result pairing logic runs. It also unifies tool-block type detection across validation and extraction via a shared `TOOL_BLOCK_TYPES` set (supporting both camelCase and snake_case variants), adds `droppedMalformedToolUseCount` to the repair report for observability, and updates the Google embedded runner to log non-zero repair counters. The change integrates cleanly with existing transcript sanitation: `sanitizeToolUseResultPairing()` now delegates to `repairToolUseResultPairing()`, which first cleans assistant content and then enforces strict provider requirements by moving matching `toolResult` messages directly after the corresponding assistant tool-call turn, dropping orphan/duplicate results, and synthesizing missing results only for valid tool calls. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - Changes are narrowly scoped to transcript sanitation, include defensive runtime checks, preserve message ordering/metadata, and are covered by targeted unit tests that exercise the new malformed-block stripping and reporting behavior. - No files require special attention <!-- greptile_other_comments_section --> **Context used:** - Context from `dashboard` - CLAUDE.md ([source](https://app.greptile.com/review/custom-context?memory=fd949e91-5c3a-4ab5-90a1-cbe184fd6ce8)) - Context from `dashboard` - AGENTS.md ([source](https://app.greptile.com/review/custom-context?memory=0d0c8278-ef8e-4d6c-ab21-f5527e322f13)) <!-- /greptile_comment -->