diff --git a/.changes/source-control/fix-lane-source-review-plugin-c60dcf4d.md b/.changes/source-control/fix-lane-source-review-plugin-c60dcf4d.md
new file mode 100644
index 00000000000..e792fae4ffd
--- /dev/null
+++ b/.changes/source-control/fix-lane-source-review-plugin-c60dcf4d.md
@@ -0,0 +1,7 @@
+---
+bump: patch
+---
+
+### Fixed
+
+- Babysit review evidence no longer unbinds both review lanes (`lane-source-changed`) for a pull request that changes `plugins/review/`. The reusable `pr-review-cli.yml` stages the review plugin from claude-code-plugins' default-branch tip, never the head, so a pull request's copy feeds no review. `scripts/ci-review-plugin-source.test.sh` fails if either review caller stops calling that reusable pinned to a commit SHA or passes it a plugin path. Every other lane-source path still unbinds.
diff --git a/plugins/source-control/skills/babysit-prs/scripts/babysit_review_evidence.py b/plugins/source-control/skills/babysit-prs/scripts/babysit_review_evidence.py
index c725ca9af9b..7f69f70efcd 100644
--- a/plugins/source-control/skills/babysit-prs/scripts/babysit_review_evidence.py
+++ b/plugins/source-control/skills/babysit-prs/scripts/babysit_review_evidence.py
@@ -51,9 +51,7 @@
 # What a pull request's own checkout can feed or forge for its own review:
 # its workflows (a pull_request event runs the head's copy of the callers, and
 # any workflow it adds can post a github-actions[bot] reviewed-head marker),
-# the review plugin path (the reusable stages it from main, so this is
-# caution against a caller that loads it from the checkout), Claude Code project config and instruction files at
-# any depth, the criteria the lane skills read from the checkout (REVIEW.md,
+# Claude Code project config and instruction files at any depth, the criteria the lane skills read from the checkout (REVIEW.md,
 # the standards index, the instruction exception register, the
 # untrusted-content contract), the lane's input directory .claude-lane/ (the
 # code lane falls back to a context file there), and .gitattributes, which can
@@ -61,10 +59,13 @@
 # from a checkout of main and the reusable runs its composites from its own
 # repository, so the rest of .github/ feeds no review. A pull request that
 # changes any listed path may have changed its own review, so its records
-# prove no review by the default branch's lane.
+# prove no review by the default branch's lane. plugins/review/ is not listed:
+# the reusable pr-review-cli.yml stages the review plugin from
+# claude-code-plugins' default-branch tip, never the head, and
+# scripts/ci-review-plugin-source.test.sh fails if a caller stops calling it
+# pinned to a SHA or passes it a plugin path.
 LANE_SOURCE_PREFIXES = (
     ".github/workflows/",
-    "plugins/review/",
     "docs/standards/",
     "docs/conventions/instruction-exception-register/",
     "docs/conventions/untrusted-content/",
diff --git a/plugins/source-control/skills/babysit-prs/scripts/tests/test_babysit_review_evidence.py b/plugins/source-control/skills/babysit-prs/scripts/tests/test_babysit_review_evidence.py
index 485ab34b734..6a354d116ac 100644
--- a/plugins/source-control/skills/babysit-prs/scripts/tests/test_babysit_review_evidence.py
+++ b/plugins/source-control/skills/babysit-prs/scripts/tests/test_babysit_review_evidence.py
@@ -330,7 +330,6 @@ def test_a_change_to_a_file_the_review_reads_from_the_checkout(self) -> None:
         for path in (
             ".github/workflows/pr-review-hosted.yml",
             ".github/workflows/pr-review-security-hosted.yml",
-            "plugins/review/skills/security-review/SKILL.md",
             ".claude/settings.json",
             "plugins/foo/.claude/rules/x.md",
             ".mcp.json",
@@ -361,6 +360,35 @@ def test_a_change_to_a_file_the_review_reads_from_the_checkout(self) -> None:
                 for lane in LANES:
                     self.assertUnbound(result[lane], "lane-source-changed")
 
+    def test_a_review_plugin_change_binds_both_lanes(self) -> None:
+        # The reusable stages the review plugin from the default branch's
+        # tip, never the head (scripts/ci-review-plugin-source.test.sh pins
+        # the callers to that), so a pull request's copy feeds no review.
+        for path in (
+            "plugins/review/skills/security-review/SKILL.md",
+            "plugins/review/skills/code-review/SKILL.md",
+            "plugins/review/agents/lane-verifier.md",
+            "plugins/review/.claude-plugin/plugin.json",
+            "plugins/review",
+        ):
+            with self.subTest(path):
+                result = self.bound("app.py", path)
+                for lane in LANES:
+                    self.assertTrue(result[lane].bound, lane)
+
+    def test_a_review_plugin_change_beside_lane_source_still_unbinds(self) -> None:
+        for other in (
+            ".github/workflows/pr-review-hosted.yml",
+            "docs/standards/README.md",
+            ".claude-lane/pr-context.md",
+            "plugins/review/CLAUDE.md",
+            "plugins/review/.claude/settings.json",
+        ):
+            with self.subTest(other):
+                result = self.bound("plugins/review/skills/code-review/SKILL.md", other)
+                for lane in LANES:
+                    self.assertUnbound(result[lane], "lane-source-changed")
+
     def test_a_path_that_is_not_a_string_binds_no_lane(self) -> None:
         result = self.bound("app.py", None)  # type: ignore[arg-type]
         for lane in LANES:
diff --git a/scripts/ci-review-plugin-source.test.sh b/scripts/ci-review-plugin-source.test.sh
new file mode 100755
index 00000000000..0fdae1758c1
--- /dev/null
+++ b/scripts/ci-review-plugin-source.test.sh
@@ -0,0 +1,79 @@
+#!/usr/bin/env bash
+# Structure test: each review caller runs melodic-software/ci-workflows'
+# pr-review-cli.yml pinned to a commit SHA and passes it no input naming a
+# plugin path. That reusable stages the review plugin from claude-code-plugins'
+# default-branch tip, never the pull request's head, so the review-evidence
+# binder (babysit_review_evidence.py) does not list plugins/review/ as lane
+# source. A caller that loaded the plugin from its checkout would let a pull
+# request change its own review, and this test fails first.
+# test-scope: .github/workflows/pr-review-hosted.yml .github/workflows/pr-review-security-hosted.yml plugins/source-control/skills/babysit-prs/scripts/babysit_review_evidence.py .github/standards/runner-policy/package.json
+set -uo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+# shellcheck source=lib/test-harness.sh
+. "$ROOT/scripts/lib/test-harness.sh"
+
+results=$(
+  cd "$ROOT" && node --input-type=module - <<'EOF'
+import { readFileSync } from "node:fs";
+import { createRequire } from "node:module";
+const require = createRequire(`${process.cwd()}/.github/standards/runner-policy/package.json`);
+const YAML = require("yaml");
+
+const say = (good, text) => console.log(`${good ? "ok" : "fail"}\t${text}`);
+const REUSABLE = "melodic-software/ci-workflows/.github/workflows/pr-review-cli.yml@";
+
+// The problems with one caller's jobs, or [] when it is sound.
+function problems(jobs) {
+  const calls = Object.entries(jobs ?? {}).filter(
+    ([, job]) => typeof job?.uses === "string" && job.uses.includes("pr-review-cli.yml"),
+  );
+  if (calls.length !== 1) return [`${calls.length} jobs call pr-review-cli.yml, want 1`];
+  const [id, job] = calls[0];
+  const found = [];
+  if (!job.uses.startsWith(REUSABLE) || !/^[0-9a-f]{40}$/.test(job.uses.slice(REUSABLE.length))) {
+    found.push(`job ${id} uses '${job.uses}', not ${REUSABLE}<40-hex SHA>`);
+  }
+  for (const [key, value] of Object.entries(job.with ?? {})) {
+    if (/plugin/i.test(key) || /plugins?\//i.test(String(value))) {
+      found.push(`job ${id} passes ${key}: '${value}', a plugin path`);
+    }
+  }
+  return found;
+}
+
+for (const file of ["pr-review-hosted.yml", "pr-review-security-hosted.yml"]) {
+  const wf = YAML.parse(readFileSync(`.github/workflows/${file}`, "utf8"));
+  const found = problems(wf.jobs);
+  say(found.length === 0,
+    `${file} calls pr-review-cli.yml at a commit SHA with no plugin path${found.length ? `: ${found.join("; ")}` : ""}`);
+}
+
+// The check itself rejects each shape it guards against.
+const sha = "4fbceb4b75ffd568dfa5db31de0d0e753c0c64e6";
+const call = (uses, inputs) => ({ review: { uses, with: inputs } });
+for (const [name, jobs] of [
+  ["a tag ref", call(`${REUSABLE}v0.65.9`, {})],
+  ["a short SHA", call(`${REUSABLE}${sha.slice(0, 12)}`, {})],
+  ["another repository's copy", call(`someone/ci-workflows/.github/workflows/pr-review-cli.yml@${sha}`, {})],
+  ["a plugin-dirs input", call(`${REUSABLE}${sha}`, { "plugin-dirs": "plugins/review" })],
+  ["a plugin path in another input", call(`${REUSABLE}${sha}`, { extra: "./plugins/review" })],
+  ["no call to the reusable", { review: { "runs-on": "ubuntu-latest" } }],
+  ["two calls to the reusable", { ...call(`${REUSABLE}${sha}`, {}), again: { uses: `${REUSABLE}${sha}` } }],
+]) {
+  say(problems(jobs).length > 0, `the check rejects ${name}`);
+}
+say(problems(call(`${REUSABLE}${sha}`, { lane: "code", "hold-label": "needs-human" })).length === 0,
+  "the check accepts a SHA-pinned call with no plugin path");
+EOF
+)
+status=$?
+if [[ $status -ne 0 || -z "$results" ]]; then
+  fail "the node check did not run (exit $status)"
+fi
+while IFS=$'\t' read -r verdict text; do
+  [[ -n "$verdict" ]] || continue
+  if [[ "$verdict" == ok ]]; then ok "$text"; else fail "$text"; fi
+done <<<"$results"
+
+test_harness::report