Move to actioncable-client v2

[jeremy]

basecamp/actioncable-go was renamed to basecamp/actioncable-client and became a multi-language repository. The Go client now lives in go/ as the module github.com/basecamp/actioncable-client/go/v2. This moves us from github.com/basecamp/actioncable-go v1.1.0 to github.com/basecamp/actioncable-client/go/v2 v2.0.2.

API changes absorbed

None needed at call sites. Between v1.1.0 and v2.0.2 the exported API only grew:

• added ErrMessageTooBig, *HandshakeError, *CloseError, the StatusCloser interface, and a Version constant
• nothing removed or renamed; the package is still actioncable

The imports now carry an explicit actioncable name, because the path ends in go/v2 and goimports (in make lint) asks for it.

Behavior verified

client.go, options.go, dispatcher.go and subscription.go are byte-identical between v1.1.0 and v2.0.2. That means WithStopOnError, which stops reconnecting on an authentication failure (#466, actioncable-client#9), works exactly as before.

• TestAuthenticationFailureStopsAReconnect and TestOnlyAuthenticationFailuresStopReconnects pass against v2.0.2 with -race -count=1. With the WithStopOnError line removed, the first test fails with "client kept reconnecting after authentication failed", so it really does test the library's behavior.
• make check passes.

The v2 behavior changes are all in the built-in WebSocket transport, and none of them affects us:

• a refused upgrade returns *HandshakeError, with the same message as before
• a server close frame returns *CloseError; a close frame with no code now gives *CloseError{Code: 1005} where it used to give io.EOF
• a message that is too big wraps ErrMessageTooBig
• the default User-Agent is actioncable-client, but we set our own in the header func

Nothing here compares transport errors to io.EOF or to message strings.

nix/package.nix: the vendorHash is updated to the hash the nix-build job computed for the new module.

Docs: the link in AGENTS.md (which was missing its scheme) and the two API-COVERAGE.md rows now point to actioncable-client.

Overlap with open PRs

Two open PRs change nearby lines: #473 changes the hey-sdk line in go.mod, which is right next to this one, and #344 and #185 change AGENTS.md in other sections. Whichever lands second may need a one-line rebase. None of them conflicts in the code.

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-22T22:11:43.520389Z	f33fe8b	Manual request

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[Copilot]

Copilot review overview

🟡 Changes recommended

The dependency bump leaves the Nix vendor hash stale, causing the required Nix build to fail.

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Review effort: Balanced
Findings: 1

Open (1)

• Update nix/package.nix vendorHash after Go dependency change · New

What changed in this PR

Migrates Action Cable to its renamed v2 Go module while preserving existing watch behavior.

Changes:

• Updates dependency/import paths to actioncable-client/go/v2.
• Updates tests and Action Cable documentation.
• Leaves the required Nix vendorHash update outstanding.

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File	Description
internal/​cmd/​watch.go	Updates Action Cable import.
internal/​cmd/​watch_test.go	Updates test import.
internal/​cmd/​watch_new_test.go	Updates new-mail test import.
internal/​cmd/​watch_calendar.go	Updates calendar watch import.
internal/​cmd/​tui_watch.go	Updates TUI watch import.
internal/​cmd/​tui_watch_test.go	Updates TUI watch test import.
internal/​cable/​cable.go	Migrates cable client import.
internal/​cable/​cable_test.go	Migrates cable tests.
go.mod	Replaces the v1 module with v2.
go.sum	Updates module checksums.
API-COVERAGE.md	Renames the documented client.
AGENTS.md	Updates the project link and module description.

---

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[jeremy]

@codex review

[Copilot]

Copilot review overview

🟢 Approved

The new module exists, preserves the consumed API, updates every import, and includes synchronized checksum and Nix metadata.

Review effort: Balanced
Findings: None

Resolved since last review (1)

• Update nix/package.nix vendorHash after Go dependency change

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. What shall we delve into next?

Reviewed commit: f33fe8bd46

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