fix(loops): record disabled_reason on auto-pause

[charlesvien]

Problem

Loops auto-pause after 5 consecutive failed fires (including usage-gate blocks), but unlike the lifecycle pauses (owner deactivated, GitHub disconnected) the kill-switch leaves disabled_reason null. A tripped loop reads as enabled=false with no recorded cause, so clients can't tell an auto-paused loop from one its owner paused, or say why it stopped.

Changes

The kill-switch now records why it paused the loop:

• disabled_reason="usage_limited" when the pause was tripped by the cloud usage gate in fire_loop.
• disabled_reason="repeated_failures" when tripped by a failed run reaching the threshold in handle_loop_run_terminal.

Re-enabling already clears the field and resumes schedules via facade/loops.py::update_loop, so recovery needs no changes. The field is already exposed by LoopSerializer; a companion desktop PR (PostHog/code#3779) renders the new values.

How did you test this code?

Extended the existing auto-pause tests in test_loop_runs.py to assert the recorded reason on both pause paths, and the below-threshold tests to assert the field stays null (the regression caught: a pause that flips enabled without recording a cause, or a reason written before the threshold). Ran test_loop_runs.py + test_loop_lifecycle.py locally: 50 passed. Ruff lint and format clean.

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

Docs update

N/A

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Authored with Claude Code (Fable 5). The session mapped the loops firing/kill-switch path and the existing lifecycle pause conventions, confirmed the usage gate and auto-pause already existed, and made the smallest change that lets clients render the pause cause: reuse the existing disabled_reason mechanism rather than adding a new status field or notification type. No repo skills were invoked.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "record disabled reason on loop auto-paus..." | Re-trigger Greptile}

[posthog-bot-comment-resolver]

🔀 Tried to auto-resolve conflicts with master but this one needs a human.

I won't retry until the branch or master moves.

[stamphog]

Small, contained fix that records an existing disabled_reason field on two already-existing auto-pause paths; author owns the code with strong familiarity, tests cover both new and null cases, no unresolved concerns.

• Author wrote 100% of the modified lines and has 9 merged PRs in these paths (familiarity STRONG).
• 👍 on the PR from greptile-apps[bot], hex-security-app[bot].

Gate mechanics and policy version

Gate		Result
prerequisites	✓	all clear
deny-list	✓	no deny categories matched
size	✓	19L, 1F substantive, 25L/2F incl. docs/generated/snapshots — within ceiling
tier	✓	T1-agent / T1b-small (25L, 2F, single-area, fix)
stamphog 2.0.0b3		.stamphog/policy.yml @ c711851 · reviewed head 92cbea8

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-07-24 05:12 UTC	Run
prod-us	✅ Deployed	2026-07-24 05:25 UTC	Run
prod-eu	✅ Deployed	2026-07-24 05:27 UTC	Run