Add a simple just throttle script for Mac.

[kixelated]

thx Claude

[coderabbitai]

Walkthrough

Adds a new local development script dev/throttle for macOS that configures PF/dummynet-based network throttling. The script sets fixed bandwidth, delay, and queue size, backs up and injects an anchor into pf.conf, loads the modified PF configuration, and applies a UDP-only dummynet pipe. It runs until interrupted and handles SIGINT/SIGTERM by restoring the original pf.conf, removing the dummynet pipe, and disabling PF if possible. Also adds a throttle target to the justfile that runs dev/throttle.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: adding a 'just throttle' script for Mac, which matches the new throttle target in the justfile and the dev/throttle script.
Description check	✅ Passed	While minimal, the description 'thx Claude' is a casual acknowledgment related to the changeset and shows it was created with AI assistance, though it lacks substantive detail.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@dev/throttle`:
- Around line 33-55: The script currently traps only SIGINT/SIGTERM and modifies
PF state/config without guaranteeing restoration; add a robust cleanup function
(referenced by the existing trap cleanup) that captures PF enabled state before
changes, restores the original PF config by copying PF_BACKUP back to PF_CONF,
reloads that config with pfctl -f, re-enables or disables PF to the prior state,
deletes the dummynet pipe via dnctl pipe PIPE_NUM delete, and removes the anchor
if needed; register cleanup for EXIT and ERR (in addition to SIGINT/SIGTERM) so
failures after the pf modifications always invoke cleanup and ensure any pfctl
-E enabling is conditional based on the captured previous state.

🧹 Nitpick comments (2)

dev/throttle (1)

17-18: Avoid a fixed /tmp backup path.

Line 17 uses a predictable /tmp/pf.conf.backup, which can be clobbered by concurrent runs or pre-existing files. Use a unique mktemp path instead.

♻️ Suggested change

-PF_BACKUP="/tmp/pf.conf.backup"
+PF_BACKUP="$(mktemp -t pf.conf.backup.XXXXXX)"
+chmod 600 "$PF_BACKUP"

justfile (1)

417-419: Guard the target on non‑macOS hosts.

Since this is macOS-only, adding an OS check prevents confusing failures on Linux/Windows.

♻️ Suggested guard

 # Throttle UDP traffic for testing (macOS only, requires sudo)
 throttle:
-	dev/throttle
+	`@if` [ "$(uname)" != "Darwin" ]; then \
+		echo "throttle is macOS-only"; \
+		exit 1; \
+	fi
+	dev/throttle