fix: clarify capability preflight lifetime across safe reads (Closes #470)

Add preflight_contract helpers with explicit re-resolve error messages, document the read-only tool set and consumption rules, and extend tests for close_pr sequencing and task replacement. Validation: ./venv/bin/python -m pytest tests/test_preflight_read_survival.py tests/test_mcp_server.py::TestPreflightVerification -q Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
2026-07-08 02:28:07 -04:00
parent 2d4ab4e54e
commit a8bcbdbcf2
4 changed files with 147 additions and 6 deletions
@@ -0,0 +1,66 @@
+"""Capability preflight lifetime contract (#470).
+
+Defines which read-only MCP tools preserve an existing capability proof and the
+canonical sequencing operators must follow before mutations.
+"""
+
+from __future__ import annotations
+
+# Read-only tools that must not invalidate capability proof (#470).
+# gitea_whoami is read-only but re-pins identity; capability is preserved when
+# identity was already verified clean (#469).
+READ_ONLY_PREFLIGHT_TOOLS = frozenset({
+    "gitea_whoami",
+    "gitea_get_authenticated_user",
+    "gitea_get_current_user",
+    "gitea_view_pr",
+    "gitea_view_issue",
+    "gitea_list_prs",
+    "gitea_list_issues",
+    "gitea_list_issue_comments",
+    "gitea_get_runtime_context",
+    "gitea_resolve_task_capability",
+    "gitea_check_pr_eligibility",
+    "gitea_get_pr_review_feedback",
+    "gitea_assess_work_issue_duplicate",
+    "gitea_route_task_session",
+    "gitea_audit_config",
+    "gitea_list_labels",
+    "gitea_get_profile",
+    "gitea_list_profiles",
+})
+
+PREFLIGHT_CONTRACT_SUMMARY = (
+    "Capability preflight is session-scoped per MCP process, profile, and task. "
+    "After gitea_resolve_task_capability(task=...), interleaved read-only calls "
+    "(whoami, view_*, list_*, get_runtime_context, eligibility checks) preserve "
+    "the proof until a gated mutation consumes it. Each mutation consumes the proof "
+    "once; re-resolve immediately before the next mutation. A new resolve for a "
+    "different task replaces the prior task binding. Profile/session changes or "
+    "workspace edits before resolve invalidate proof."
+)
+
+
+def format_missing_capability_error(task: str | None = None) -> str:
+    base = (
+        "Pre-flight order violation: Task capability "
+        "(gitea_resolve_task_capability) has not been resolved (fail closed)"
+    )
+    if task:
+        return (
+            f"{base}. Re-run gitea_resolve_task_capability(task=\"{task}\") "
+            "immediately before this mutation."
+        )
+    return (
+        f"{base}. Re-run gitea_resolve_task_capability for the mutation task "
+        "immediately before acting."
+    )
+
+
+def format_task_mismatch_error(resolved: str, required: str) -> str:
+    return (
+        "Pre-flight task mismatch: "
+        f"resolved '{resolved}' but mutation requires '{required}' (fail closed). "
+        f"Re-run gitea_resolve_task_capability(task=\"{required}\") "
+        "immediately before this mutation."
+    )