[TEP-0137] Activate formats field in config-events

[afrittoli]

Dependencies (stacked):

• [TEP-0137] Deprecate send-cloudevents-for-runs feature flag #9774
• [TEP-0137] Move PipelineRun notifications to events controller #9677
• [TEP-0137] Move TaskRun notifications to events controller #9674
• [TEP-0137] Rework the events controller cache #6914
• [TEP-0137] Restructure customrun event controller #6889

Once the dependencies are merged, the PR will contain 1 commit only.

Future PRs

• Add CDEvents support
• Add Tekton v2 support (with v1 resources)

Changes

Activate the formats field in config-events by making EmitCloudEvents format-aware.

• Refactor EmitCloudEvents to read cfg.Events.Formats from context and iterate over configured formats, dispatching to per-format senders. The L1 object-level cache check runs once before the format loop, not once per format.
• Extract dispatchCloudEvent as the shared delivery core for all formats: L2 event-level cache check, goroutine dispatch, exponential-backoff retries, and Kubernetes Event recording (CloudEventSent/CloudEventFailed). PR7 format senders will call this without duplicating any delivery logic.
• Add sendTektonV1Event as the first format-specific sender; it builds the tektonv1 event and delegates to dispatchCloudEvent.
• Slim SendCloudEventWithRetries to a thin wrapper over dispatchCloudEvent; its public contract is unchanged.
• EmitCloudEventsWhenConditionChange is unchanged (calls SendCloudEventWithRetries directly; remains deprecated).
• Remove stale TODO comment from validFormats in pkg/apis/config/events.go.
• Add "Event formats" section to docs/events.md; add one clarifying sentence to docs/additional-configs.md.

Adding a future format (tektonv2, cdevents) requires only a new eventForRunObject variant, a sendFormat function, and a case in the EmitCloudEvents switch — no changes to dispatchCloudEvent or ReconcileRunObject.

Submitter Checklist

As the author of this PR, please check off the items in this checklist:

• Has Docs if any changes are user facing, including updates to minimum requirements e.g. Kubernetes version bumps
• Has Tests included if any functionality added or changed
• Follows the commit message standard
• Meets the Tekton contributor standards (including functionality, content, code)
• Has a kind label. You can add one by adding a comment on this PR that contains /kind <type>. Valid types are bug, cleanup, design, documentation, feature, flake, misc, question, tep
• Release notes block below has been updated with any user facing changes (API changes, bug fixes, changes requiring upgrade notices or deprecation warnings). See some examples of good release notes.
• Release notes contains the string "action required" if the change requires additional action from users switching to the new release

Release Notes

The formats field in config-events is now active. The default value is
tektonv1, which preserves existing behaviour. Setting an invalid or
unrecognised format value logs a warning and suppresses event emission
for that format.

/kind feature

[tekton-robot]

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[twoGiants]

Just a first question so far. Tests review is pending ... ⌚ 😺

[twoGiants]

`This function is retained for callers that manage their own gating (e.g. EmitCloudEventsWhenConditionChange).

Will this function also be remove once EmitCloudEventsWhenConditionChange will be removed?

[afrittoli]

Good catch, I should deprecate this function as well, so it will be removed once EmitCloudEventsWhenConditionChangeis removed.

[github-actions]

Merging this branch will increase overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/tektoncd/pipeline/pkg/apis/config	87.87% (ø)
github.com/tektoncd/pipeline/pkg/reconciler/events/cloudevent	65.18% (+2.07%)	👍
github.com/tektoncd/pipeline/pkg/reconciler/notifications	100.00% (ø)
github.com/tektoncd/pipeline/pkg/reconciler/notifications/pipelinerun	92.31% (ø)
github.com/tektoncd/pipeline/pkg/reconciler/notifications/taskrun	92.31% (ø)

---

Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/tektoncd/pipeline/pkg/apis/config/events.go	98.15% (ø)	54	53	1
github.com/tektoncd/pipeline/pkg/reconciler/events/cloudevent/cloud_event_controller.go	82.72% (+1.76%)	81 (+18)	67 (+16)	14 (+2)	👍

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

Changed unit test files

• github.com/tektoncd/pipeline/pkg/reconciler/events/cloudevent/cloud_event_controller_test.go
• github.com/tektoncd/pipeline/pkg/reconciler/notifications/pipelinerun/reconciler_test.go
• github.com/tektoncd/pipeline/pkg/reconciler/notifications/runtimeobject_test.go
• github.com/tektoncd/pipeline/pkg/reconciler/notifications/taskrun/reconciler_test.go

[afrittoli]

/retest