feat: add explicit SUBSCRIBE message to initiate subscriptions

[jbedard]

This way binaries such as aspect_gazelle_runner or formatters can specify they want to receive CYCLE events for any source changes, not only runfiles changes like today.

Changes are visible to end-users: no

Test plan

• Covered by existing test cases
• Manual testing

[Copilot]

Pull Request Overview

This PR introduces protocol versioning and an explicit subscription model for the incremental build protocol. The changes enable clients to negotiate protocol versions and explicitly subscribe to specific watch types (sources or runfiles).

Key changes:

• Adds protocol version negotiation with support for version 0 (legacy) and version 1 (with explicit subscribe)
• Refactors AwaitCycle() to Subscribe(options) returning iter.Seq2 for proper error handling
• Introduces WatchType enum to allow subscribing to specific change types (sources/runfiles)

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
runner/pkg/ibp/protocol.go	Introduces ProtocolVersion type, version constants, WatchType enum, and SubscribeMessage structure
runner/pkg/ibp/client.go	Refactors client to negotiate protocol versions and implement explicit subscription with error handling via iter.Seq2
runner/runner.go	Updates Watch method to use new Subscribe API with explicit watch type
runner/pkg/ibp/BUILD.bazel	Adds dependency on common/logger package

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[aspect-workflows]

Test

All tests were cache hits

3 tests (100.0%) were fully cached saving 233ms.

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Test

language/js

All tests were cache hits

117 tests (100.0%) were fully cached saving 20s.

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Test

language/kotlin

All tests were cache hits

19 tests (100.0%) were fully cached saving 3s.

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Test

language/orion

All tests were cache hits

49 tests (100.0%) were fully cached saving 10s.

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Test

runner

9 test targets passed

Targets

//tests:bad_build_test [k8-fastbuild]229ms
//tests:branded-directives_test [k8-fastbuild]324ms
//tests:crossresolve-js_test [k8-fastbuild]364ms
//tests:crossresolve-pnpm-names-lazy_test [k8-fastbuild]413ms
//tests:crossresolve-pnpm-names_test [k8-fastbuild]398ms
//tests:crossresolve-pnpm_test [k8-fastbuild]255ms
//tests:imports-missing_test [k8-fastbuild]362ms
//tests:js_binary-main_test [k8-fastbuild]364ms
//tests:npm_bin_wrapper_test [k8-fastbuild]342ms

Total test execution time was 3s. 15 tests (62.5%) were fully cached saving 1s.

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Buildifier      Gazelle      Gazelle [language/js]      Gazelle [language/kotlin]      Gazelle [language/orion]      Gazelle [runner]

[Copilot]

Pull Request Overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

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[Copilot]

Pull Request Overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

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[jbedard]

Options:

• single type
• multiple bools (source + runfiles)
• array of types

If a binary says it only wants to subscribe to sources should it be restarted if it's runfiles change? Or we should ignore runfiles? If watching both should should they be distinguished in the CYCLE message somewhere such as a sources[path]: {type: 'runfiles' | 'sources'} flag? :/

[jbedard]

rules_js support: aspect-build/rules_js#2411

[jbedard]

This will instead be done with a CAP(abilities) request+response instead and sticking with a single subscription per socket connection.

[jbedard]

Will be doing the original protocol CAP message instead