fix(node-host): fail closed on unbound interpreter approvals

docs/tools/exec-approvals.md

@@ -30,9 +30,14 @@ Trust model note:
 - Gateway-authenticated callers are trusted operators for that Gateway.
 - Paired nodes extend that trusted operator capability onto the node host.
 - Exec approvals reduce accidental execution risk, but are not a per-user auth boundary.
-- Approved node-host runs also bind canonical execution context: canonical cwd, pinned executable
-  path when applicable, and interpreter-style script operands. If a bound script changes after
-  approval but before execution, the run is denied instead of executing drifted content.
+- Approved node-host runs bind canonical execution context: canonical cwd, exact argv, env
+  binding when present, and pinned executable path when applicable.
+- For shell scripts and direct interpreter/runtime file invocations, OpenClaw also tries to bind
+  one concrete local file operand. If that bound file changes after approval but before execution,
+  the run is denied instead of executing drifted content.
+- This file binding is intentionally best-effort, not a complete semantic model of every
+  interpreter/runtime loader path. If approval mode cannot identify exactly one concrete local
+  file to bind, it refuses to mint an approval-backed run instead of pretending full coverage.
 
 macOS split:
 
@@ -259,6 +264,20 @@ For `host=node`, approval requests include a canonical `systemRunPlan` payload.
 that plan as the authoritative command/cwd/session context when forwarding approved `system.run`
 requests.
 
+## Interpreter/runtime commands
+
+Approval-backed interpreter/runtime runs are intentionally conservative:
+
+- Exact argv/cwd/env context is always bound.
+- Direct shell script and direct runtime file forms are best-effort bound to one concrete local
+  file snapshot.
+- If OpenClaw cannot identify exactly one concrete local file for an interpreter/runtime command
+  (for example package scripts, eval forms, runtime-specific loader chains, or ambiguous multi-file
+  forms), approval-backed execution is denied instead of claiming semantic coverage it does not
+  have.
+- For those workflows, prefer sandboxing, a separate host boundary, or an explicit trusted
+  allowlist/full workflow where the operator accepts the broader runtime semantics.
+
 When approvals are required, the exec tool returns immediately with an approval id. Use that id to
 correlate later system events (`Exec finished` / `Exec denied`). If no decision arrives before the
 timeout, the request is treated as an approval timeout and surfaced as a denial reason.