docs(agents): Fold pr.mdc into the create-java-pr skill - #5936

📜 Description

Deletes .cursor/rules/pr.mdc (264 lines) and gives its content a single home each:

• Conventions the skill was missing → create-java-pr/SKILL.md: allowed commit types, PR title format, changelog rebase caveat.
• Stacked-PR workflow (~150 lines) → create-java-pr/references/stacked-prs.md, loaded on demand. Git tracks this as a rename.
• Everything else → already duplicated in the skill, so dropped.

The skill now reads .github/pull_request_template.md for the PR body instead of reproducing it, with an explicit instruction never to write it from memory. AGENTS.md drops the pr row from the rule table and points its Changelog section at the skill.

Fixes found by dry-running the result

Agents were run against the deduped docs for "create a PR" and "create a stacked PR", stopping before the first mutating action. Both paths loaded the intended files — the standalone run never opened stacked-prs.md — and surfaced four defects, now fixed:

• SKILL.md named stacked-prs.md the source of truth for branch naming, which it never covered. Claim corrected to title naming.
• Four passages referenced "the collection branch PR"; no step ever opened it. Added, with its title and merge-reminder exceptions.
• The PR-description editing rule was stated three times and had already drifted (&& vs &&/||). Now stated once in SKILL.md, which both paths read.
• AGENTS.md step 7 ("propose but not execute a commit") contradicted the skill, which commits, pushes, and opens the PR. Scoped to implementation work.

💡 Motivation and Context

pr.mdc and the skill described the same six-step workflow. The skill opened by declaring pr.mdc "required reading … the source of truth," then re-implemented every step anyway. Both inlined the PR template and the changelog subsection table.

Nobody on the team uses Cursor, so the split bought nothing — it just doubled the surface that had to stay in sync. And it hadn't: both inlined templates were missing a checklist item .github/pull_request_template.md has since gained:

- [ ] Public API changes reviewed by another Mobile SDK team member or implemented
      according to the develop docs spec

Every PR created through the skill silently dropped it. Pointing at the template file makes that class of drift impossible.

💚 How did you test it?

Docs-only — no code paths affected.

• Dry-ran both PR flows with fresh agents; verified the file sets read, and that every fix above resolves a defect an agent actually hit.
• No references to pr.mdc remain.
• The PR template's section headers appear in exactly one file.
• The AGENTS.md rule table matches .cursor/rules/ exactly (12 rules, 12 rows).
• Spotless covers only Java/Kotlin, so no formatting run applies.

📝 Checklist

• I added GH Issue ID & Linear ID
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.
• Public API changes reviewed by another Mobile SDK team member or implemented according to the develop docs spec.

🔮 Next steps

Remaining duplication, in order of payoff:

• AGENTS.md repeats ./gradlew spotlessApply apiDump across nine lines; the Makefile is the source of truth. (CONTRIBUTING.md also documents a make format target that doesn't exist — one-line fix held back for its own PR, which this one should follow.)
• Changelog rules still live in both AGENTS.md and the skill.
• Test invocation appears in AGENTS.md, test/SKILL.md, and e2e_tests.mdc; the skill's module→task table is the accurate one.
• Step 0 of the skill has no branch for "this branch already has an open PR" — four dry runs produced four different plans for that case.
• The 12 remaining .cursor/rules/ files are arguably misfiled if nobody uses Cursor, but rehoming them touches every rule reference.

#skip-changelog