feat: route bot-authored PRs to per-repo owner instead of skipping (#8)

Adds bot_pr_owners map keyed by repo name. When a PR author is in
bot_authors (dependabot, renovate, claude, copilot review bot, listed
external contributors), the workflow now requests the mapped owner as
reviewer instead of exiting 0.

Mapping:
  lisk-backend  -> ishantiw
  lisk-web      -> mmarinovic
  lisk-mobile   -> 5heri
  lisk-infra    -> Nazgolze
  lisk-contracts-> matjazv

Repos without a bot_pr_owners entry retain the old skip behavior, so
this is opt-in per repo.

Implementation:
- review-map.yml: add bot_pr_owners section + clarify bot_authors comment
- auto-assign-reviewer.yml: hoist EXISTING fetch above bot path so the
  bot path can short-circuit on idempotency; replace skip with route +
  request + comment + soft-fail (mirrors the squad cascade's failure
  semantics).
- validate-review-map.yml: assert every bot_pr_owners key is in
  enabled_repos; include bot_pr_owners values in the GitHub-user
  existence check.
- docs/auto-reviewer.md: document the bot short-circuit, add the
  current owner table, update kill-switch list.

Author: shuse2

.github/workflows/auto-assign-reviewer.yml

@@ -96,9 +96,36 @@ jobs:
             exit 0
           fi
 
-          # ── Bot-author skip ──────────────────────────────────────────────
+          # ── Already-requested reviewers (idempotency) ────────────────────
+          # Fetched up-front so both the bot-author path and the squad
+          # cascade can short-circuit if the chosen reviewer is already
+          # requested.
+          EXISTING=$(gh api "repos/$REPO/pulls/$PR_NUMBER/requested_reviewers" --jq '.users[].login' 2>/dev/null || true)
+
+          # ── Bot-author / external-author routing ─────────────────────────
+          # Bots and listed external contributors bypass the squad cascade
+          # because they have no squad. Route them to the repo's bot_pr_owner
+          # if one is mapped; otherwise skip.
           if jq -r '.bot_authors[]' "$MAP_JSON" | grep -Fxq "$PR_AUTHOR"; then
-            log "auto-reviewer: skipping bot/external author '$PR_AUTHOR'."
+            BOT_OWNER=$(jq -r --arg r "$REPO_NAME" '.bot_pr_owners[$r] // ""' "$MAP_JSON")
+            if [ -z "$BOT_OWNER" ] || [ "$BOT_OWNER" = "null" ]; then
+              log "auto-reviewer: bot/external author '$PR_AUTHOR' on $REPO_NAME has no bot_pr_owners mapping. Skipping."
+              exit 0
+            fi
+            if printf '%s\n' "$EXISTING" | grep -Fxq "$BOT_OWNER"; then
+              log "auto-reviewer: $BOT_OWNER already requested on PR #$PR_NUMBER (bot path). Skipping."
+              exit 0
+            fi
+            log "auto-reviewer: routing bot/external author '$PR_AUTHOR' → $BOT_OWNER (repo owner for $REPO_NAME)"
+            if ! gh api -X POST "repos/$REPO/pulls/$PR_NUMBER/requested_reviewers" \
+                  -f "reviewers[]=$BOT_OWNER" >/dev/null 2>err.log; then
+              ERR=$(cat err.log || true)
+              warn "auto-reviewer: failed to request $BOT_OWNER for bot PR: $ERR"
+              comment "🤖 **Auto-reviewer:** tried to request review from \`@$BOT_OWNER\` for bot/external author \`$PR_AUTHOR\` but the API rejected it (likely not a collaborator on this repo). Please assign a reviewer manually."
+              exit 0
+            fi
+            comment "🤖 **Auto-reviewer:** requested review from @$BOT_OWNER — repo owner for bot/external author \`$PR_AUTHOR\`."
+            log "auto-reviewer: bot-path success."
             exit 0
           fi
 
@@ -115,9 +142,6 @@ jobs:
 
           log "auto-reviewer: author=$PR_AUTHOR squad=$AUTHOR_SQUAD domain=$DOMAIN repo=$REPO_NAME pr=$PR_NUMBER"
 
-          # ── Already-requested reviewers (idempotency) ────────────────────
-          EXISTING=$(gh api "repos/$REPO/pulls/$PR_NUMBER/requested_reviewers" --jq '.users[].login' 2>/dev/null || true)
-
           # ── Cascade resolution ───────────────────────────────────────────
           SELECTED=""
           REASON=""

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

@@ -7,6 +7,7 @@ name: Validate review-map.yml
 #   - Every domain key in specialists is one of: backend|web|infra|mobile|contracts
 #   - Every squad name in sibling_fallback_order exists under .squads
 #   - Each squad's TL is also in members (when not null)
+#   - Every bot_pr_owners key matches an entry in enabled_repos
 
 on:
   pull_request:
@@ -86,6 +87,14 @@ jobs:
             fi
           done < <(jq -r '.squads | to_entries[] | [.key, (.value.tl // "")] | @tsv' "$MAP_JSON")
 
+          # bot_pr_owners keys must be in enabled_repos
+          while IFS=$'\t' read -r repo owner; do
+            [ -z "$repo" ] && continue
+            if ! jq -r '.enabled_repos[]' "$MAP_JSON" | grep -Fxq "$repo"; then
+              err "bot_pr_owners key '$repo' is not in enabled_repos"
+            fi
+          done < <(jq -r '.bot_pr_owners // {} | to_entries[] | [.key, .value] | @tsv' "$MAP_JSON")
+
           # fallback_to_squad_members_for entries must be valid domains
           while IFS=$'\t' read -r squad domain; do
             [ -z "$domain" ] && continue
@@ -141,6 +150,7 @@ jobs:
             jq -r '
               [
                 (.bot_authors // [])[],
+                (.bot_pr_owners // {} | to_entries[].value),
                 (.squads[].members // [])[],
                 (.squads[].tl // empty),
                 (.squads[].specialists // {} | to_entries[].value[])

docs/auto-reviewer.md

@@ -24,7 +24,13 @@ specialist." This workflow does that with one shared map.
 
 ## Cascade
 
-Given PR author `A`, repo domain `D`, author squad `S`:
+**Bot / external authors short-circuit before the cascade.** If the PR author
+is in `bot_authors`, the workflow requests the repo's `bot_pr_owners[<repo>]`
+(if mapped) and exits. Bots have no squad and don't need round-robin
+distribution; a single per-repo owner is enough. If no owner is mapped for
+the repo, the workflow exits 0 silently.
+
+Given a human PR author `A`, repo domain `D`, author squad `S`:
 
 1. **Own-squad specialists.** If `S.specialists[D]` minus `A` is non-empty,
    pick `eligible[PR# % len]`.
@@ -84,10 +90,33 @@ siblings.
 
 - **All assignment off:** set `enabled: false` in `review-map.yml`.
 - **One repo off:** remove it from `enabled_repos`.
-- **Skip a specific author:** add login to `bot_authors`.
+- **Bypass squad cascade for an author:** add login to `bot_authors`. They get
+  routed to `bot_pr_owners[<repo>]` if mapped, otherwise skipped.
+- **Stop bot routing in a repo:** remove the repo from `bot_pr_owners` (bot
+  PRs in that repo will then be skipped).
 
 All take effect on the next PR open with no other action.
 
+## Bot / external author routing
+
+`bot_pr_owners` maps repo name → single GitHub login. Designed for PRs where
+squad-based routing doesn't apply: dependabot bumps, renovate bumps, claude
+PR commits, copilot review bot, plus listed external contributors.
+
+Current mapping:
+
+| Repo            | Owner       |
+|-----------------|-------------|
+| `lisk-backend`  | `ishantiw`  |
+| `lisk-web`      | `mmarinovic`|
+| `lisk-mobile`   | `5heri`     |
+| `lisk-infra`    | `Nazgolze`  |
+| `lisk-contracts`| `matjazv`   |
+
+The owner is requested verbatim — no round-robin, no domain check, no
+fallback. If they're unavailable, the comment trail surfaces who the API
+rejected so a human can re-assign.
+
 ## What does and doesn't fail the workflow
 
 The workflow is best-effort. It always exits 0 (so it never blocks merges)

review-map.yml

@@ -17,7 +17,8 @@ enabled_repos:
   - lisk-mobile
   - lisk-contracts
 
-# Authors to skip entirely (no assignment, exit 0).
+# Authors that bypass the squad cascade. They get routed to the repo's
+# bot_pr_owner (see below) if one is set, otherwise the workflow exits 0.
 bot_authors:
   - dependabot[bot]
   - renovate[bot]
@@ -26,6 +27,17 @@ bot_authors:
   - copilot-pull-request-reviewer[bot]
   - bmijac  # external contributor on lisk-web
 
+# Per-repo owner for bot-authored / external-author PRs. Keyed by repo
+# name (must match an entry in enabled_repos). When a PR author is in
+# bot_authors, the mapped owner is requested instead of running the
+# squad cascade. If a repo has no entry here, bot PRs are skipped.
+bot_pr_owners:
+  lisk-backend: ishantiw
+  lisk-web: mmarinovic
+  lisk-mobile: 5heri
+  lisk-infra: Nazgolze
+  lisk-contracts: matjazv
+
 # Domain equivalence — within a squad, specialists for an equivalent domain
 # may review when no specialist exists for the requested domain. This stays
 # the review inside the squad. Equivalence does NOT apply to sibling cascade