[AAASM-4959] 🔧 (config): Migrate default branch master → main (outbound refs)

[Chisanan232]

Description

Default-branch migration for python-sdk (master → main) per ADR 0016 (Accepted). The GitHub branch rename has already been performed (default is now main, protection moved, master redirects). This PR sweeps the outbound in-tree references the rename does not touch.

Functional refs flipped:

• CI branch filters — push/pull_request/workflow_run branches: on all workflows (ci.yaml, benchmarks.yml, codeql.yml, documentation.yaml, framework-resolution-check.yml, native-pin-consistency.yml, quickstart-tabs-check.yml, readme-version-check.yml, release-python-conversion-test.yml, type-check.yml, wheel-python-matrix.yml).
• github.ref_name == 'master' conditionals in rw_build_and_test.yaml / rw_run_all_test_and_record.yaml.
• actions/checkout ref: master in documentation.yaml + docs-backfill.yaml.
• Operator dispatch commands gh workflow run … --ref master in docs/release/RUNBOOK.md and the sdk-only-release / release-runbook skills (these hard-break after rename — the ref is gone).
• README shields.io badges (?branch=master), codecov.yml (branch / strict_yaml_branch), mkdocs.yml (edit_uri).
• Convention docs — CONTRIBUTING.md base-branch + worktree commands, .claude/CLAUDE.md base-branch + remote/master guidance.

Intentionally NOT changed:

• External Chisanan232/…@master reusable-workflow refs (different repo's default branch — ADR 0016 §6).
• Redirect-covered github.com/…/blob/master · /tree/master · /commits/master web links in docs/** (cosmetic per ADR 0016 §6; GitHub 301-redirects them).
• Historical verification-reports/** (records of past runs).

Type of Change

• 🔧 Bug fix (release/CI migration — config)
• 📚 Documentation update

Breaking Changes

• No — the rename itself moved the default + protection and installs a master→main redirect. This PR keeps CI firing on main and keeps operator runbooks accurate.

Related Issues

• Related JIRA ticket: AAASM-4959 (Epic AAASM-4955)

Lockstep dependency

The release-coupling with agent-assembly is handled in a separate PR on agent-assembly (base master, since that repo is not yet migrated): it flips the PYTHON_SDK_BOT_TOKEN create-pull-request step base: master → main in .github/workflows/release.yml and the check-release-completeness.sh drift guard. Both land in the same window as this rename.

Testing

• Static: git grep confirms no functional master ref remains (branch filters / ref: / --ref / ?branch= / ref_name); only cosmetic redirect-covered web links and external @master refs remain.
• Rename verified: default = main; branch protection (1 approval + code-owner review) re-verified on main; no master branch recreated.
• No unit/integration tests required — config/docs only.

Checklist

• Code follows project style guidelines
• Self-review completed
• Documentation updated

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[Chisanan232]

🤖 Claude Code review (evidence only — merge is a Pioneer reviewer's call)

Part of the python-sdk master → main migration (AAASM-4959, ADR 0016). This PR fixes python-sdk's own branch-name refs after the default-branch rename.

• Rename: default_branch=main, protection (1 review) moved to main, master redirects, no master branch remains.
• Scope: outbound branch-filter refs + docs only. Cross-repo links use rename-proof /blob/HEAD/.
• Release lockstep (separate PR): the agent-assembly release.yml python bot-PR base: + the drift-guard map are flipped to main in agent-assembly#1624 — must merge in the same window so the next release opens the python pin-bump PR against main.
• CI: green (27 pass / 0 fail).

Not self-merged. Evidence only.

[Chisanan232]

🤖 Claude Code review (evidence only — merge is a Pioneer reviewer's call)

1. CI — ✅ green (27 pass / 0 fail / 7 skip). 2. CodeCov/SonarCloud — ✅ no issues (the codecov.yml change is only branch/strict_yaml_branch master→main, i.e. the coverage default-branch — no threshold/gate change).

3. Scope vs AAASM-4959 — ✅ complete. python-sdk master→main migration: 22 files, 54 -master / 54 +main (perfectly balanced) — workflow branch filters, docs, README, CONTRIBUTING, mkdocs, codecov default-branch. Release lockstep is in the paired agent-assembly#1624 (must merge together).

4. Side effects — ✅ none. Pure branch-reference migration (every removed master replaced by main; zero logic/job/threshold edits). No product/business-logic code touched.

5. Front-end — n/a. No FE source changed (workflows + Markdown + CI config only) → Playwright not applicable.

Verdict: ready for approval + merge. Not self-merged.