chore(ci): build a dedicated experiments recalculation worker image

[rodrigoi]

Problem

The stacked PR routes experiment metrics recalculation to a dedicated experiments-recalculation-task-queue served by its own worker. That worker needs its image state kept current in PostHog/charts, but the CD pipeline has no dispatch for it, so its deploy state would never advance past the seeded value.

Changes

Wires the new temporal-worker-experiments-recalculation release into the container-images CD pipeline. There is no new image build; every temporal worker shares the posthog-cloud image, and each worker just gets a repository-dispatch to PostHog/charts that writes the freshly built digest into its own release state.

Adds a change-detection step scoped to the recalc worker's paths and a matching dispatch for its release. The recalc temporal path moves off the general-purpose worker's change filter, since recalc no longer runs on that worker.

• .github/workflows/container-images-cd.yml

Rollback

Revert this PR. The worker keeps running on whatever image its charts state already points at; only automatic image tracking for this release stops.

Deploy order

Stacked on top of the queue-routing PR. Order within the stack does not matter for correctness: until the dedicated worker exists in charts, this dispatch simply updates a release nothing consumes yet. It becomes load-bearing once the charts worker is live.

How did you test this code?

Agent-run: validated that the workflow YAML parses and that the new change-detection step, its if gate, and the release dispatch are consistent. CI exercises the dispatch on merge.

python3 -c "import yaml; yaml.safe_load(open('.github/workflows/container-images-cd.yml'))"

Automatic notifications

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

Docs update

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Model: Opus 4.8
Manually refactored: no

Skills used:

• /writing-pull-requests (local)

Relevant decisions:

• Cloned the existing single-worker dispatch pattern (change-detection step, if gate, repository-dispatch with a per-release name) rather than introducing a new image build, since all temporal workers share the posthog-cloud image and differ only by dispatched release.
• Removed products/experiments/backend/temporal/ from the general-purpose worker's change filter; recalc was the only general-registered code under that path, so leaving it would rebuild the general image on every recalc change for no reason.

[rodrigoi]

• chore(ci): build a dedicated experiments recalculation worker image #67261 👈 (View in Graphite)
• feat(experiments): route metrics recalculation to its own temporal queue #67257
• master

This stack of pull requests is managed by Graphite. Learn more about stacking.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "chore(experiments): update container ima..." | Re-trigger Greptile}

[greptile-apps]

_{Reviews (2): Last reviewed commit: "chore(experiments): update container ima..." | Re-trigger Greptile}

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-07-03 17:20 UTC	Run
prod-us	✅ Deployed	2026-07-03 17:35 UTC	Run
prod-eu	✅ Deployed	2026-07-03 17:36 UTC	Run