CH-045: Document current Rumble rankings

[flemming-n-larsen]

Acceptance brief

• Plan item and whether it remains wanted: plan-less CH-045; it remains wanted because robocode.dev needs the canonical explanation for the ranking behavior accepted in merged robocode-dev/rumble-data#12.
• Vision: this repository states no vision, so the change proceeds without one.
• RBC-005 — “Hourly catalog polling publishes only changed reviewed content”: verifies-something-adjacent; external integration evidence exercises changed and unchanged synchronization and asserts the serialized workflow/skip contract, but does not execute the hosted no-op path end to end.
• RDA-006 — “APS gives each distinct pairing equal weight within the active ranking epoch”: verifies; external integration evidence covers pairing-first averaging, counts, active-version and behavior-epoch exclusion, zero-sample entries, and stable ties.
• RDA-007 — “Publication freshness changes only when current ranking data changes”: verifies-something-adjacent; external integration evidence covers ranking-tree freshness and snapshot stability, while dispatch/reconciliation checks are static workflow assertions.
• RDA-008 — “The first writer after a UTC month boundary preserves immutable cumulative history”: verifies; external integration evidence covers missing months, byte-for-byte copies, first-deployment behavior, partial recovery, and overwrite refusal.
• RDA-009 — “A dashboard viewer can distinguish current rankings from read-only monthly history”: verifies-something-adjacent; external E2E-tagged evidence checks the shipped page and selection paths statically rather than driving a browser.
• What becomes binding on merge: the public /rumble/rankings contract and aligned CAP-014/CAP-015 meanings; all five new criteria remain @draft until external evidence can be registered locally. No decision record is added, invalidated, or superseded.

Summary

• Add the canonical robocode.dev guide for exact APS calculation, active bot versions, behavior epochs, update cadence, meaningful freshness, and immutable cumulative month-end snapshots.
• Link it from the Rumble navigation and author, client, moderator, and overview pages.
• Align the durable Rumble design and capability carriers with merged rumble-data#12, while keeping the live data and dashboard in rumble-data.
• Document the user-visible change in CHANGELOG.md.

Verification

• npm run build in web: passed (VitePress; existing chunk-size warning only).
• clue validate --forbid-changes: passed.
• git diff --check origin/main HEAD: passed.
• python -m unittest discover -s tests -v in rumble-data: 41 tests passed.
• Adversarial review: in-context fallback, 2 passes; pass 1 found and repaired the month-rollover exception to unchanged catalog publication, and pass 2 found no blocking or advisory findings.

Cliewen proposal

• Change ID: CH-045
• Change tier: full
• Plan item served: explicitly plan-less
• Proposal location: changes/CH-045-document-rumble-rankings/proposal.md at proposal commit 562915672; removed by the digest as required.
• Agentic review mode and reviewed commit: in-context fallback; 329af8c3bfb73d3307a4ccbe621e91d0350b45bd
• Hosted head reviewed before this update: 329af8c3bfb73d3307a4ccbe621e91d0350b45bd
• Outstanding actionable findings: none

Traceability and decisions

• Acceptance criteria or capability meaning changed: RBC-005, RDA-006, RDA-007, RDA-008, and RDA-009; CAP-014 and CAP-015 documentation aligned.
• Decision records added or changed: none; the implementation documents behavior already accepted in rumble-data#12.
• Constraints assessed: C-001 passed via clue validate; C-002 is satisfied by this branch and human-merge boundary; C-003 and C-004 do not apply because no Bot API, physics, or compatibility behavior changes.
• Documentation impact: added the canonical public ranking guide and updated public navigation/audience guidance, the Rumble cross-cutting design, both affected capability carriers, and the changelog.

Cliewen checklist

• This is the initiating author's only initiated Cliewen change.
• The proposal was committed and pushed before implementation.
• The plan-less declaration is truthful, and artifact links resolve.
• No future-shaping decision required a decision record; active constraints were assessed.
• New criteria remain @draft, with their external scenario-resolution verdicts recorded above.
• User-visible impact is under the unreleased changelog entry.
• Tasks are complete, bookkeeping is current, and no transient CH-045 workspace remains.
• Generated indexes were regenerated from canonical sources.
• Commit 329af8c3bfb73d3307a4ccbe621e91d0350b45bd received a clean second review pass.
• Every intended edit is committed, the worktree is clean, and the branch contains current origin/main.
• The hosted head equals the locally verified branch and commit.
• This PR remains human-merged; no agent will merge it or push this change to main.