feat: round-robin within team when no domain specialist is eligible

[shuse2]

Summary

• Make Step 3 (squad-wide fallback) unconditional in auto-assign-reviewer.yml. Previously gated by each squad's fallback_to_squad_members_for list; now any author whose own-squad domain specialists are exhausted (or who is the sole specialist) gets routed to a teammate via PR# round-robin before the sibling cascade fires.
• Sole specialists like matjazv (backend/contracts in org), vardan10 (backend in money), ricott1 (contracts in global), and Nazgolze (infra in platform) now stay in-team for review instead of crossing to a sibling squad.
• Drop the now-redundant fallback_to_squad_members_for field from review-map.yml and its validator block in validate-review-map.yml.
• Update docs/auto-reviewer.md cascade description and matrix legend to reflect the new in-team-priority behavior.

Test plan

• yq -o=json review-map.yml | jq . parses cleanly with the field removed.
• Trace: matjazv opens backend PR #N → Step 1 yields [matjazv] - matjazv = [] → Step 2 no equivalence → Step 3 picks org.members - matjazv round-robin (mmarinovic, mvuco00, ikem-legend, mislavtomic).
• Trace: vardan10 opens backend PR #N → Step 3 picks from money.members - vardan10 round-robin (oskarleonard, Balanced02, eniolam1000752, 5heri).
• Trace: sameersubudhi opens backend PR → Step 1 still picks ishantiw (specialists keep priority over generic team round-robin).
• Trace: Nazgolze opens infra PR → Step 3 picks from platform.members - Nazgolze (same end-state as the old gated fallback).
• validate-review-map.yml passes on the updated map (no orphaned fallback_to_squad_members_for references).

Summary by CodeRabbit

• New Features

  • Bot and external author pull requests now route to designated repository owners.

• Improvements

  • Enhanced reviewer assignment with earlier deduplication and squad-wide round-robin fallback when specialists aren’t available.
  • Eliminated prior repo-specific fallback behavior (infra-specific case removed).
  • Review requests are best-effort and soft-fail with clearer rejection handling.

• Documentation

  • Updated reviewer routing docs to reflect bot routing and revised cascade order.

• Validation

  • Configuration validation now ensures bot owner mappings reference enabled repositories and real accounts.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 8191ff08-9875-463a-bda2-9ccff6cd5e45

📥 Commits

Reviewing files that changed from the base of the PR and between 79aae64 and 7b509b7.

📒 Files selected for processing (4)

• .github/workflows/auto-assign-reviewer.yml
• .github/workflows/validate-review-map.yml
• docs/auto-reviewer.md
• review-map.yml

💤 Files with no reviewable changes (1)

• .github/workflows/validate-review-map.yml

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📝 Walkthrough

Walkthrough

This PR refactors PR reviewer auto-assignment by adding per-repo bot author routing, moving idempotency checks earlier, replacing domain-gated squad fallback with squad-wide round-robin fallback, and updating validation and documentation accordingly.

Changes

Bot-authored PR routing with squad cascade refactor

Layer / File(s)	Summary
Configuration Schema review-map.yml	Introduces bot_pr_owners per-repo mapping for routing bot-authored PRs; clarifies bot_authors behavior; updates comments for sibling fallback logic.
Workflow Bot Routing & Cascade .github/workflows/auto-assign-reviewer.yml	Implements bot author early-exit with bot_pr_owners lookup, moves idempotency fetch earlier, replaces domain-gated fallback_to_squad_members_for with squad-wide round-robin fallback using all squad members when no specialist selected.
Validation .github/workflows/validate-review-map.yml	Validates bot_pr_owners repository keys exist in enabled_repos; extends login verification to include bot owner handles.
Documentation docs/auto-reviewer.md	Documents bot author early-exit cascade bypass, clarified step-by-step human author cascade (own-squad specialist → equivalent → round-robin → sibling), kill switch controls, and explicit bot routing behavior with no fallback or domain logic.

Sequence Diagram(s)

sequenceDiagram
  participant PR as PR Event
  participant WF as auto-assign-reviewer workflow
  participant Config as review-map.yml
  participant GH as GitHub API
  PR->>WF: trigger
  WF->>WF: fetch already-requested reviewers
  WF->>Config: lookup bot_pr_owners[repo] if author in bot_authors
  alt bot owner mapped
    WF->>GH: request mapped owner
    GH-->>WF: accept/reject
  else no mapping
    WF-->>PR: exit silently
  end
  WF->>Config: run squad cascade for human authors (specialist → eq-domain → round-robin → sibling)
  WF->>GH: request selected reviewer

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Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• LiskHQ/workflows#8: Both PRs implement bot-authored PR routing via per-repo bot_pr_owners mapping, replace bot-author skip with idempotent route-and-request in auto-assign-reviewer.yml, and update validation and documentation.

Poem

🐰 I hop through configs, maps, and flows,
Bot authors routed where the mapping goes,
Round-robin hums when specialists hide,
Validators check keys with pride,
A tiny rabbit guards the review road.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: implementing squad-wide round-robin fallback when no domain specialist is eligible, which is the core feature introduced across all modified files.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch chore/route-bot-prs-to-repo-owner

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