ably: make Channels.Release return an error unless the channel is detached (RTS4c-e)

[SimonWoolf]

Implements RTS4c–e from spec 6.3.0 (ably/specification#557) for the next major version.

Breaking change. RealtimeChannels.Release is now Release(name string) error:

• If no channel with that name exists, it returns nil (RTS4c).
• If the channel is INITIALIZED, DETACHED or FAILED, it is removed from the collection before Release returns (RTS4d).
• Otherwise it returns an *ably.ErrorInfo with code 90011 (ably.ErrChannelReleaseInvalidState) and statusCode 400, and the channel and collection are left unchanged (RTS4e). It no longer detaches the channel for you.
• Because it no longer blocks on a detach, it no longer takes a context.Context.

Why: under the old behaviour the channel stayed in the collection while the detach was in flight. A Get for the same name in that window returned the channel that was about to be removed, which then received no further messages. Releasing a FAILED channel also failed, since detaching a FAILED channel is an error.

Migration: detach and wait before releasing.

if err := channel.Detach(ctx); err != nil {
    return err
}
if err := client.Channels.Release(channel.Name); err != nil {
    return err
}

90011 is registered in ably/ably-common#367, but the common submodule pin isn't bumped here, because scripts/errors can't parse the current errors.json format. The constant is added by hand to error_names.go.

The current-major deprecation is in #716. Reference ably-js PRs: ably/ably-pubsub-js#2322 (deprecation) and ably/ably-pubsub-js#2323 (next major).

🤖 Generated with Claude Code

Summary by CodeRabbit

• Behavior Changes
  • Releasing a channel now succeeds only when it is initialized, detached, or failed. Channels in other states remain in the collection and return an error with status 400.
  • Detach an attached channel before releasing it. Releasing a channel that does not exist returns no error.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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• Run ID: 7f9bbe17-3faf-415a-b91e-b0a6b0a510c0

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📥 Commits

Reviewing files that changed from the base of the PR and between 24bd01a and 1c4eaf0.

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📒 Files selected for processing (5)

• ably/error_names.go
• ably/realtime_channel.go
• ably/realtime_channel_integration_test.go
• ably/realtime_channel_internal_test.go
• ably/state.go

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Walkthrough

RealtimeChannels.Release no longer accepts a context or detaches channels. It removes existing channels only in INITIALIZED, DETACHED, or FAILED states. For other states, it returns error code 90011 with status 400.

Changes

Realtime channel release

Layer / File(s)	Summary
Define releasable states ably/error_names.go, ably/state.go	Adds error code 90011 and a state check that allows release in INITIALIZED, DETACHED, and FAILED states.
Validate and remove channels ably/realtime_channel.go, ably/realtime_channel_integration_test.go, ably/realtime_channel_internal_test.go	Updates Release to reject non-releasable states without removing the channel. Tests cover missing channels, releasable states, rejected states, and explicit detachment before release.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~12 minutes

Change: Bug fix

Suggested reviewers: ttypic, lmars

Merge Risk: ⚪ Minimal · up to 1c4ea

Release now rejects channels that are not detached, as intended for the breaking API change. No concrete defects remain. Releasing a channel from its detached event handler does not deadlock.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 20.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 5 functions across 5 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly identifies the main change to Channels.Release and the invalid-state behavior. It is concise and directly related to the pull request, although it does not mention the additional rel…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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_{A rabbit checks each channel’s state
And waits until the time is right
The detached ones can hop away
The others stay, unchanged in place
A code nine-zero-zero-one-one marks the gate
Then carrots celebrate the night}

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[ttypic]

LGTM