[Phase 4] Safe custom Finder actions, macOS Shortcuts, and keyboard access #10

Priority: P2
Parent roadmap: #1
Depends on: stable contextual action registry and job execution (see #4).

Vision

Allow power users to invoke their own explicitly configured actions on selected files, without turning Tuck into an unrestricted or opaque automation daemon.

Scope

• A small settings editor for named custom actions: title, optional SF Symbol, compatible selection types, sort/order, command/script or macOS Shortcut reference, and confirmation requirement.
• Placeholder/argument interface that passes selected paths safely via argv or a structured manifest; never interpolate untrusted filenames into a shell command string.
• Support invoking installed macOS Shortcuts by stable identification where platform APIs/CLI support it; verify run/cancel/error behavior.
• Support user-chosen executable scripts with explicit consent, working directory, environment policy, bounded runtime and output/log redaction.
• Expose standard Tuck operations through suitable macOS Services/Quick Actions where technically supported; allow keyboard shortcuts without stealing native Finder shortcuts or registering fragile global key monitors.
• Disable/remove/reorder actions; show exactly what will run and which files it receives.
• Security: no default network/shell scripts, no bundled unsafe recipes, no privilege escalation, no secrets in environment/debug logs. Don't silently run scripts on untrusted downloads.

Acceptance criteria

• Selecting appropriate Finder files exposes only compatible custom actions.
• Filenames with quotes, spaces, Unicode, newlines and leading dashes cannot inject extra arguments or shell syntax.
• Action execution is asynchronous with progress when possible; cancellation terminates only job-owned children.
• User can inspect and revoke custom action permissions.
• Config persists and migrates safely; no unrestricted script executed because of a malformed preference.
• Shortcut execution and keyboard use have actionable errors when permissions/integration are missing.

Tests

Command argument-injection fixtures, invalid/removed scripts, denied permissions, huge selection, launch failures, timeouts, cancellation, environment sanitation, conflicting shortcuts and Finder extension restarts. Preserve authenticated helper IPC.