**4 issues found** across 25 files Confidence score: **2/5** - There is a high-confidence, high-severity issue in `packages/core/lib/v3/agent/tools/upload.ts`: raw exception messages are returned without sanitization, which can expose resolved variables or local file paths in tool output. - `packages/core/lib/v3/agent/tools/upload.ts` also uses `path.basename` in an OS-dependent way, creating a concrete risk of leaking full Windows paths when executed on non-Windows runtimes. - Both `packages/core/lib/v3/agent/tools/type.ts` and `packages/core/lib/v3/agent/tools/fillFormVision.ts` validate only raw values, so `%variable%` substitutions can bypass upload/file-path guards and allow local file paths to be typed. - Pay close attention to `packages/core/lib/v3/agent/tools/upload.ts`, `packages/core/lib/v3/agent/tools/type.ts`, and `packages/core/lib/v3/agent/tools/fillFormVision.ts` - these paths contain the main leakage and guard-bypass risks that should be fixed before merge.

Prompt for AI agents (unresolved issues)

```text Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately. P2: `path.basename` is OS-dependent here and can leak full Windows paths on non-Windows runtimes. P1: Custom agent: **Exception and error message sanitization** Do not expose raw exception messages in tool output; return a sanitized error string to avoid leaking resolved variables or local file paths. P2: The upload guard only inspects the raw field values; any `%variable%` that expands to a local file path will bypass the guard even though the substituted value is what gets typed. Run the guard against the substituted value so file uploads can’t slip through fillFormVision. P2: Run the file-upload guard on the substituted text; `%variable%` file paths currently bypass the guard and allow the type tool to enter local file paths. ```

Architecture diagram

```mermaid sequenceDiagram participant LLM as AI Model / LLM participant Agent as Agent Handler (DOM/Hybrid/CUA) participant Tools as Standard Tools (click, type, act, etc.) participant Guard as NEW: File Upload Guard participant Upload as NEW: Upload Tool participant V3 as V3 Service (observe) participant Page as Browser Page (Playwright) participant Cache as Agent Cache / Replay Note over LLM, Cache: Agent Execution Flow LLM->>Agent: Call tool (e.g., click, type, fillForm) Agent->>Tools: execute(params) Tools->>Guard: NEW: getFileUploadGuardError(text/action) alt NEW: Intent or local path detected in standard tool Guard-->>Tools: Return "Use upload tool" error Tools-->>Agent: Fail with Guard Error Agent-->>LLM: Error: Request 'upload' tool instead else No upload intent Note right of Guard: Normal tool execution end Note over LLM, Cache: Native Upload Flow LLM->>Agent: NEW: Call 'upload' tool Agent->>Upload: execute(target, paths) Upload->>Upload: Substitute %variables% in paths Upload->>V3: NEW: observe("find actual for target") V3-->>Upload: Return selector for real input element alt Selector found Upload->>Page: NEW: setInputFiles(selector, paths) opt Replay Active Upload->>Cache: NEW: recordAgentReplayStep(type: "upload") end Upload-->>Agent: Success (summarized basenames) else Selector not found Upload-->>Agent: Fail (helpful instruction error) end Agent-->>LLM: Tool Result Note over Cache, Page: Replay Flow (Later) Cache->>Page: NEW: replayAgentUploadStep() Page->>Page: setInputFiles(cached selector, paths) ```

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