When the user pressed ESC (or Deny / Abort) on an approval prompt, the
TUI correctly told the engine to deny the call. But the model would
often retry the same command — same name, same args, same approval
fingerprint — and the user would see the dialog again, frustrating in
the same way the equivalent yes-yes-yes loop would be.
Symmetric to the existing `approval_session_approved` "always approve"
cache: add `approval_session_denied: HashSet<String>` populated when
the user denies (not when the timeout fired — a timeout might mean
the user stepped away rather than refused). Subsequent ApprovalRequired
events whose approval_key or tool_name match the cache auto-deny via
`engine.deny_tool_call(...)` without re-showing the dialog. Logged via
`tool.approval.auto_deny_session` so the audit log captures the silent
denial.
Closes#360.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Hunter Bown
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