fix(auto-merge): harden mutable review evidence

.github/tests/merge-gate-fixtures/cr-approval-edited-after-changes-requested/comments.json

@@ -0,0 +1,9 @@
+[
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "body": "<!-- This is an auto-generated comment: summarize by coderabbit.ai -->\n<!-- pre_merge_checks_walkthrough_start -->\n<summary>🚥 Pre-merge checks | ✅ 5</summary>\n<!-- pre_merge_checks_walkthrough_end -->",
+    "created_at": "2026-07-11T11:30:00Z"
+  }
+]

.github/tests/merge-gate-fixtures/cr-approval-edited-after-changes-requested/reviews.json

@@ -0,0 +1,22 @@
+[
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "state": "APPROVED",
+    "commit_id": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "submitted_at": "2026-07-11T10:00:00Z",
+    "last_edited_at": "2026-07-11T12:00:00Z",
+    "body": "Approval body edited after the later verdict."
+  },
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "state": "CHANGES_REQUESTED",
+    "commit_id": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "submitted_at": "2026-07-11T11:00:00Z",
+    "last_edited_at": null,
+    "body": "A later red verdict must remain authoritative."
+  }
+]

.github/tests/merge-gate-fixtures/cr-approval-edited-after-dismissal/comments.json

@@ -0,0 +1,9 @@
+[
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "body": "<!-- This is an auto-generated comment: summarize by coderabbit.ai -->\n<!-- pre_merge_checks_walkthrough_start -->\n<summary>🚥 Pre-merge checks | ✅ 5</summary>\n<!-- pre_merge_checks_walkthrough_end -->",
+    "created_at": "2026-07-11T11:30:00Z"
+  }
+]

.github/tests/merge-gate-fixtures/cr-approval-edited-after-dismissal/reviews.json

@@ -0,0 +1,22 @@
+[
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "state": "APPROVED",
+    "commit_id": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "submitted_at": "2026-07-11T10:00:00Z",
+    "last_edited_at": "2026-07-11T12:00:00Z",
+    "body": "Approval body edited after the later dismissal."
+  },
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "state": "DISMISSED",
+    "commit_id": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "submitted_at": "2026-07-11T11:00:00Z",
+    "last_edited_at": null,
+    "body": "A later dismissal must remain authoritative."
+  }
+]

.github/tests/merge-gate-fixtures/cr-changes-requested-then-approval/comments.json

@@ -0,0 +1,9 @@
+[
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "body": "<!-- This is an auto-generated comment: summarize by coderabbit.ai -->\n<!-- pre_merge_checks_walkthrough_start -->\n<summary>🚥 Pre-merge checks | ✅ 5</summary>\n<!-- pre_merge_checks_walkthrough_end -->",
+    "created_at": "2026-07-11T11:30:00Z"
+  }
+]

.github/tests/merge-gate-fixtures/cr-changes-requested-then-approval/reviews.json

@@ -0,0 +1,22 @@
+[
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "state": "CHANGES_REQUESTED",
+    "commit_id": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "submitted_at": "2026-07-11T10:00:00Z",
+    "last_edited_at": "2026-07-11T12:00:00Z",
+    "body": "The older red verdict body was edited later."
+  },
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "state": "APPROVED",
+    "commit_id": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "submitted_at": "2026-07-11T11:00:00Z",
+    "last_edited_at": null,
+    "body": "A later approval supersedes the earlier red verdict."
+  }
+]

.github/tests/merge-gate-fixtures/index.json

@@ -95,6 +95,18 @@
     "name": "cr-approval-superseded-at-head",
     "expect_green": false
   },
+  {
+    "name": "cr-approval-edited-after-changes-requested",
+    "expect_green": false
+  },
+  {
+    "name": "cr-approval-edited-after-dismissal",
+    "expect_green": false
+  },
+  {
+    "name": "cr-changes-requested-then-approval",
+    "expect_green": true
+  },
   {
     "name": "cr-approval-dismissed-at-head",
     "expect_green": false
@@ -135,6 +147,10 @@
     "name": "premerge-warning-full",
     "expect_green": false
   },
+  {
+    "name": "premerge-full-pass-only-in-explanation",
+    "expect_green": false
+  },
   {
     "name": "premerge-stale-before-head",
     "expect_green": false

.github/tests/merge-gate-fixtures/premerge-full-pass-only-in-explanation/comments.json

@@ -0,0 +1,9 @@
+[
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "body": "<!-- This is an auto-generated comment: summarize by coderabbit.ai -->\n<!-- pre_merge_checks_walkthrough_start -->\n## Pre-merge checks\n| Check | Status | Details |\n| --- | --- | --- |\n| Title check | ✅ Passed | Current result |\n| Linked Issues | Pending | Previous result: ✅ Passed |\n<!-- pre_merge_checks_walkthrough_end -->",
+    "created_at": "2026-07-11T10:00:00Z"
+  }
+]

.github/tests/merge-gate-fixtures/premerge-full-pass-only-in-explanation/reviews.json

@@ -0,0 +1,10 @@
+[
+  {
+    "user": {
+      "login": "coderabbitai[bot]"
+    },
+    "state": "APPROVED",
+    "commit_id": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "submitted_at": "2026-07-11T10:00:00Z"
+  }
+]

.scripts/check-merge-gates.sh

@@ -62,15 +62,15 @@ premerge_state="not-posted"
 
 # CodeRabbit's verdict at the head is its LATEST verdict-bearing review there:
 # an APPROVED superseded by CHANGES_REQUESTED (or dismissed) must not count.
+# Verdict chronology is submission chronology; editing an older review body
+# must not make its verdict supersede a later state transition.
 cr_latest_verdict_at_head="$(jq -r --arg sha "$head_sha" '
-  def effective_at:
-    [.submitted_at, .last_edited_at] | map(select(. != null)) | max // "";
   [.[]
    | select(.user.login == "coderabbitai[bot]")
    | select(.commit_id == $sha)
    | select(.state == "APPROVED" or .state == "CHANGES_REQUESTED"
             or .state == "DISMISSED")]
-  | sort_by(effective_at) | last | .state // empty' "$reviews_json")"
+  | sort_by(.submitted_at // "") | last | .state // empty' "$reviews_json")"
 
 cr_approved_anywhere="$(jq -r '
   [.[] | select(.user.login == "coderabbitai[bot]" and .state == "APPROVED")]
@@ -100,11 +100,11 @@ cr_commented_probe="$(jq -r --arg sha "$head_sha" '
   def effective_at:
     [.submitted_at, .last_edited_at] | map(select(. != null)) | max // "";
   ([.[]
-    | select(.user.login == "coderabbitai[bot]")
-    | select(.commit_id == $sha)
-    | select(.state == "APPROVED" or .state == "CHANGES_REQUESTED"
+   | select(.user.login == "coderabbitai[bot]")
+   | select(.commit_id == $sha)
+   | select(.state == "APPROVED" or .state == "CHANGES_REQUESTED"
              or .state == "DISMISSED")]
-   | sort_by(effective_at) | last | effective_at) as $verdict_at
+   | sort_by(.submitted_at // "") | last | (.submitted_at // "")) as $verdict_at
   | [.[]
      | select(.user.login == "coderabbitai[bot]")
      | select(.commit_id == $sha)
@@ -230,18 +230,27 @@ if [[ -n "$premerge_body" ]]; then
       # Header/separator rows are ignored; an unknown/pending data row is red
       # even when another row passed. Requiring at least one data row keeps an
       # unrecognized future shape fail-closed.
-      full_check_rows="$(awk '
+      full_check_rows="$(awk -F'|' '
         /^## Pre-merge checks[[:space:]]*$/ { in_section = 1; next }
         in_section && /^##[[:space:]]/ { exit }
         in_section && /^\|/ {
           if ($0 ~ /^\|[-[:space:]:|]+\|[[:space:]]*$/) next
-          if ($0 ~ /\|[[:space:]]*(Status|Result)[[:space:]]*\|/) next
+          status = $3
+          gsub(/^[[:space:]]+|[[:space:]]+$/, "", status)
+          if (status == "Status" || status == "Result") next
           print
         }
       ' <<<"$region")"
       if [[ -n "$full_check_rows" && "$region" != *"❌"* &&
         "$region" != *"❓"* && "$region" != *"⚠️"* ]] &&
-        ! grep -qvF '✅ Passed' <<<"$full_check_rows"; then
+        awk -F'|' '
+          {
+            status = $3
+            gsub(/^[[:space:]]+|[[:space:]]+$/, "", status)
+            if (status != "✅ Passed") bad = 1
+          }
+          END { exit bad }
+        ' <<<"$full_check_rows"; then
         premerge_state="green"
       else
         premerge_state="failed"