feat(ai): durcissement phase F (#79) - rate limit, redaction, OpenAPI/MCP, E2E

backend/tools/redaction.py

@@ -0,0 +1,39 @@
+"""Secret redaction for tool results (Phase F).
+
+Tool results are fed back to the LLM (in-app agent loop) or returned to an
+external MCP client, so they must never leak credentials. ``read_file`` and
+``read_file_raw`` already redact through the shared file service, but other
+tools (``diff_backup``, ``search_*``) return content that has not been through
+the redactor. This module applies :func:`backend.secret_redactor.redact` to
+every string in a tool payload, recursively.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+from backend.secret_redactor import redact
+
+_MAX_DEPTH = 12
+
+
+def redact_payload(payload: Any, _depth: int = 0) -> Any:
+    """Return a copy of *payload* with every string secret-redacted.
+
+    Walks dicts, lists and tuples; scalars are returned unchanged. Strings are
+    run through :func:`backend.secret_redactor.redact`. A recursion cap avoids
+    pathological/cyclic structures (tool results are JSON-serialisable, so
+    cycles should not occur, but the guard keeps this safe).
+    """
+    if _depth > _MAX_DEPTH:
+        return payload
+    if isinstance(payload, str):
+        redacted, count = redact(payload)
+        return redacted if count else payload
+    if isinstance(payload, dict):
+        return {key: redact_payload(value, _depth + 1) for key, value in payload.items()}
+    if isinstance(payload, list):
+        return [redact_payload(item, _depth + 1) for item in payload]
+    if isinstance(payload, tuple):
+        return tuple(redact_payload(item, _depth + 1) for item in payload)
+    return payload