macOS Full Disk Access Grant Walkthrough

Self-Evolving Skill: This skill improves through use. If instructions are wrong, parameters drifted, or a workaround was needed — fix this file immediately, don't defer. Only update for real, reproducible issues.

What this skill is for: when a launchd-spawned binary (or any non-interactive process) needs to read sandbox-protected paths like ~/Library/Containers/<app>/Data/..., macOS TCC will deny the access until that specific binary is added to the Full Disk Access allowlist in System Settings → Privacy & Security → Full Disk Access. We cannot grant this programmatically — Apple's design — but we can automate everything up to the manual click.

Why this exists

Discovered iter 21 (2026-05-19) after the iter-20 fleet heartbeat finally surfaced a 32-day-old chronic failure in com.terryli.maccy-backup. The launchd job had been failing daily with "Maccy DB unreadable" since 2026-04-17. Root cause: the spawn binary ~/eon/iterm2-scripts/bin/maccy-backup/maccy-backup-runner was not in the FDA allowlist. Interactive shells (iTerm2, Warp, Terminal, mise binaries) all WERE — that's why running the script manually from a terminal succeeds, hiding the problem from casual debugging.

Without this helper, the click-path is buried four levels deep in System Settings, and the absolute binary path has to be typed by hand. The helper makes it a 30-second manual operation instead of "10 minutes of fumbling, abandoned, fails for another week."

How it works

fda-grant-walkthrough performs four steps:

Resolves the binary path to its absolute canonical form (System Settings stores absolute paths)
Checks the current TCC database for an existing grant (fast-exits if already granted)
Copies the absolute path to the macOS clipboard via pbcopy
Opens System Settings directly to the FDA pane via x-apple.systempreferences://...

The user then clicks + → Cmd+Shift+G → Cmd+V → Enter → select binary → toggle ON → authenticate.

After the grant, --check mode confirms the new state without opening any UI.

Usage

# Full walkthrough — opens UI, copies path
fda-grant-walkthrough ~/eon/iterm2-scripts/bin/maccy-backup/maccy-backup-runner

# Check-only — useful in scripts / CI / heartbeat-class probes
if fda-grant-walkthrough --check /path/to/binary; then
    echo "FDA already granted — proceed"
else
    echo "FDA needed — see exit code 3"
fi

Exit codes

Exit	Meaning
0	Binary already has FDA (or walkthrough launched successfully)
1	Usage error (no path given, etc.)
2	Binary does not exist or is not executable
3	(--check only) Binary does NOT have FDA, OR caller lacks FDA to read TCC.db

Install

ln -sf "$HOME/.claude/plugins/marketplaces/cc-skills/plugins/devops-tools/skills/macos-fda-grant-helper/scripts/fda-grant-walkthrough.sh" ~/.local/bin/fda-grant-walkthrough

Worked example — fixing the chronic maccy-backup failure

# 1. Run the walkthrough (System Settings opens; path on clipboard)
fda-grant-walkthrough ~/eon/iterm2-scripts/bin/maccy-backup/maccy-backup-runner

# 2. In Settings: + → Cmd+Shift+G → Cmd+V → Enter → toggle ON → Touch ID

# 3. Verify the grant landed
fda-grant-walkthrough --check ~/eon/iterm2-scripts/bin/maccy-backup/maccy-backup-runner

# 4. Restart the failing launchd job and watch for green
launchctl kickstart -p gui/$(id -u)/com.terryli.maccy-backup
tail -f ~/.local/state/maccy-backup/logs/backup-$(date +%Y%m%d).log

# 5. Tomorrow morning, fleet heartbeat (iter 20) should drop from WARN to INFO
#    because failed_services no longer includes com.terryli.maccy-backup=1

Why we can't fully automate the grant

macOS TCC enforces a human-authenticated boundary on FDA changes. There's no public API for tccutil to ADD entries — only RESET them. Even MDM (Mobile Device Management) profiles can pre-authorize FDA only for system-distributed apps, not for arbitrary user-compiled binaries. The walkthrough is therefore the optimum: 95% automated (path resolution, clipboard, UI navigation), 5% manual (the click + Touch ID).

When to use this skill

A launchd job is failing with "Operation not permitted" or "DB unreadable" or "permission denied" on paths under ~/Library/Containers/
A compiled Swift/Go binary needs to read app-private files (Maccy clipboard DB, Messages chat DB, Mail mbox, etc.)
You want a scripted way to check whether a given binary has FDA without opening any UI (use --check)

iter-20 fleet daily heartbeat — surfaced maccy-backup as the test case for this helper
macOS Privacy & Security framework: Apple docs
TCC database schema: https://rainforest.engineering/2021-02-09-macos-tcc/

Post-Execution Reflection

After granting FDA via this helper, check:

Did --check confirm the grant? — Run after toggling ON; if it still returns exit 3, the toggle may not have stuck (try toggling OFF/ON again with auth).
Did the dependent launchd job recover? — Kickstart the job and verify the next log line shows the protected path was read successfully.
Does the fleet heartbeat reflect the fix the next morning? — The iter-20 heartbeat reports failed services; a successful FDA grant should drop the entry within a day.

macos-fda-grant-helper