Scope SDK batch generation + add spec-changes manifest

[gjtorikian]

Summary

• Make generate-prs.yml workflow_dispatch-only with batch_id (required) + services (CSV, optional) inputs, so SDK regeneration targets changed services instead of fanning out over everything on push-to-main.
• Extract branch/commit/push/PR logic into scripts/open-batch-pr.mjs: deterministic oagen/batch-<id> branch, force-push idempotence, empty-diff skip, per-entry + catch-all commits, create-or-reuse PR with --dry-run gating the gh mutations.
• Forward --services through scripts/sdk-generate.sh to oagen generate (full generation when the flag is absent).
• Add scripts/build-spec-changes.mjs + .github/workflows/spec-changes.yml: on a spec merge, record .spec-changes/<sha>.json of changed post-mount services (+ hasBreaking) at the repo root, so the manifest commit re-triggers neither spec-changes.yml nor release.yml.
• Publish a dedicated sdk-compat commit status on PRs so the automation bot reads a clean breaking/non-breaking signal instead of scraping the PR comment.
• Add node:test suites (28 tests) + a captured oagen-diff fixture and a test npm script.

Test plan

• npm test passes (28 node:test cases)
• Dispatch generate-prs.yml with batch_id + services CSV; confirm only listed services regenerate into oagen/batch-<id>
• Re-run the same dispatch; confirm force-push idempotence + empty-diff skip
• Merge a spec change; confirm .spec-changes/<sha>.json is written and does not re-trigger spec-changes.yml or release.yml
• Open a PR with a breaking change; confirm the sdk-compat status reports failure (success when non-breaking)

[greptile-apps]

Greptile Summary

This PR scopes SDK batch generation to changed services (instead of fanning out over everything on push-to-main), extracts branch/commit/push/PR logic into a tested Node script (open-batch-pr.mjs), and adds a new spec-changes.yml workflow that computes a changed-services manifest on every spec merge and POSTs it HMAC-signed to the SDK automation bot.

• generate-prs.yml: Converted from push-triggered to workflow_dispatch-only with required batch_id + optional services CSV; per-entry commit/PR creation delegated to open-batch-pr.mjs; sdk-compat commit status published from validate-sdks.yml so the bot reads a clean breaking/non-breaking signal without scraping PR comments.
• spec-changes.yml: New workflow runs oagen diff + oagen parse on spec merges, builds a per-service manifest via build-spec-changes.mjs (including transitive model/enum attribution), and POSTs it to the SDK bot — nothing is committed back to this repo.
• Tests: 28 node:test cases with a local bare-repo integration harness for open-batch-pr.mjs and unit coverage for build-spec-changes.mjs including a real captured diff-report.json smoke test.

Confidence Score: 5/5

Safe to merge; the changes are well-scoped workflow orchestration with no irreversible side-effects and a solid test suite covering the critical paths.

The core logic lives in two well-tested Node scripts (28 tests, local bare-repo integration). The workflows use standard GitHub Actions patterns, the HMAC signing is correct, and the fork-PR guard in validate-sdks.yml properly addresses the statuses:write limitation. The only two findings are minor style/hygiene items — direct input interpolation in one run step and a missing --base flag — neither of which affects correctness in the current deployment context.

.github/workflows/generate-prs.yml — the Create batch PR step interpolates inputs.batch_id and inputs.services directly into the shell script, unlike the guarded env-var pattern used in the adjacent Generate SDK step.

Important Files Changed

Filename	Overview
.github/workflows/generate-prs.yml	Workflow migrated from push-triggered full-fan-out to workflow_dispatch-only with required batch_id and optional services inputs; PR creation logic delegated to open-batch-pr.mjs; direct interpolation of inputs in the batch-PR step is inconsistent with the guarded env-var pattern used in the Generate SDK step.
.github/workflows/spec-changes.yml	New workflow that diffs the spec on push-to-main, builds a changed-services manifest, and POSTs it HMAC-signed to the SDK bot; correctly uses -euo pipefail with the
.github/workflows/validate-sdks.yml	Adds sdk-compat commit status step with statuses: write permission; fork PR case is correctly gated with github.event.pull_request.head.repo.full_name == github.repository to avoid the 403 from read-only tokens on fork events.
scripts/open-batch-pr.mjs	Well-structured extraction of branch/commit/push/PR logic with dry-run gating on all gh mutations; NOOP_ONLY_FILES guard, force-push idempotence, per-entry ordered commits, and create-or-reuse PR all look correct; gh pr create lacks --base but defaults safely to repo's default branch.
scripts/build-spec-changes.mjs	Correctly transforms oagen diff report into a sorted, deduped per-service manifest; transitive model/enum attribution via buildSymbolOwners handles shared schemas and removed models; unattributed symbol changes are counted and reported on stderr without failing the build.
scripts/sdk-generate.sh	Clean addition of --services forwarding; absent/empty flag correctly skips appending to EXTRA_ARGS, preserving existing full-generation behaviour for callers that don't pass the flag.
scripts/tests/open-batch-pr.spec.mjs	Good integration tests using a real local bare-repo origin; covers empty-diff, manifest-only, force-push idempotence, per-entry commit ordering, dry-run output, and scoped-diff confinement.
scripts/tests/build-spec-changes.spec.mjs	Comprehensive unit tests covering mount-rule remapping, breaking-flag rollup, shared-model transitive attribution, behavior changes, and a real-fixture smoke test against the captured diff-report.json.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant Spec as openapi-spec repo
    participant SCW as spec-changes.yml
    participant Bot as SDK Automation Bot
    participant GPW as generate-prs.yml
    participant OBP as open-batch-pr.mjs
    participant SDK as SDK Repo

    Spec->>SCW: "push to main on spec/**"
    SCW->>SCW: oagen diff + oagen parse
    SCW->>SCW: build-spec-changes.mjs builds manifest
    SCW->>Bot: POST /internal/spec-changes HMAC-signed
    Bot->>Bot: store manifest, compute batch_id
    Bot->>GPW: workflow_dispatch with batch_id and services
    GPW->>GPW: npm run sdk:generate with services scope
    GPW->>OBP: batch-id, lang, services, sdk-dir
    OBP->>SDK: checkout branch oagen/batch-ID
    OBP->>SDK: per-entry commits and force-push
    OBP->>SDK: gh pr create or reuse existing PR
    OBP-->>GPW: pr_number, pr_url, branch
    GPW->>SDK: add changelog fragment if bullets present
    GPW->>Spec: gh api statuses for sdk-compat signal

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sequenceDiagram
    participant Spec as openapi-spec repo
    participant SCW as spec-changes.yml
    participant Bot as SDK Automation Bot
    participant GPW as generate-prs.yml
    participant OBP as open-batch-pr.mjs
    participant SDK as SDK Repo

    Spec->>SCW: "push to main on spec/**"
    SCW->>SCW: oagen diff + oagen parse
    SCW->>SCW: build-spec-changes.mjs builds manifest
    SCW->>Bot: POST /internal/spec-changes HMAC-signed
    Bot->>Bot: store manifest, compute batch_id
    Bot->>GPW: workflow_dispatch with batch_id and services
    GPW->>GPW: npm run sdk:generate with services scope
    GPW->>OBP: batch-id, lang, services, sdk-dir
    OBP->>SDK: checkout branch oagen/batch-ID
    OBP->>SDK: per-entry commits and force-push
    OBP->>SDK: gh pr create or reuse existing PR
    OBP-->>GPW: pr_number, pr_url, branch
    GPW->>SDK: add changelog fragment if bullets present
    GPW->>Spec: gh api statuses for sdk-compat signal

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_{Reviews (3): Last reviewed commit: "refactor(spec-changes): push the manifes..." | Re-trigger Greptile}