diff --git a/.github/workflows/docker-runner-check.yml b/.github/workflows/docker-runner-check.yml
index 8ada4807851..cc04223f4b7 100644
--- a/.github/workflows/docker-runner-check.yml
+++ b/.github/workflows/docker-runner-check.yml
@@ -612,6 +612,14 @@ jobs:
         with:
           ref: ${{ needs.authorize_manual.outputs.target_sha }}
           persist-credentials: false
+      - name: Checkout trusted read-only executable observer
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
+        with:
+          ref: ${{ github.workflow_sha }}
+          path: .trusted-source-observer
+          sparse-checkout: scripts/ci/source-observer/executable_holders.py
+          sparse-checkout-cone-mode: false
+          persist-credentials: false
       - name: Record immutable source and planned checks
         env:
           SOURCE_SHA: ${{ needs.authorize_manual.outputs.target_sha }}
@@ -621,6 +629,9 @@ jobs:
         run: |
           set -euo pipefail
           mkdir -p remote-source-verification
+          git -C .trusted-source-observer rev-parse HEAD > remote-source-verification/observer-source.txt
+          test "$(cat remote-source-verification/observer-source.txt)" = "${{ github.workflow_sha }}"
+          sha256sum .trusted-source-observer/scripts/ci/source-observer/executable_holders.py > remote-source-verification/observer-helper.sha256
           git rev-parse HEAD > remote-source-verification/source.txt
           test "$(cat remote-source-verification/source.txt)" = "$SOURCE_SHA"
           printf '%s\n' "$EXPECTED_LOCK_SHA256" > remote-source-verification/expected-resolved-lock.sha256
@@ -719,9 +730,21 @@ jobs:
           progress_pid=
           checks_started_at=$(date +%s)
           trap 'if [ -n "$progress_pid" ]; then kill "$progress_pid" 2>/dev/null || true; fi' EXIT
+          observe_holders() {
+            # Exact executable identity only: no argv/environment reads or signals.
+            timeout --signal=TERM --kill-after=2s 10s python3 -B \
+              .trusted-source-observer/scripts/ci/source-observer/executable_holders.py \
+              --target "$GITHUB_WORKSPACE/packages/paperclip-runner/dist/bin/paperclip-runnerd" \
+              > "remote-source-verification/check-$index-holders-$1.json" \
+              2> "remote-source-verification/check-$index-holders-$1.stderr"
+            observer_status=$?
+            printf '%s\n' "$observer_status" > "remote-source-verification/check-$index-holders-$1.status"
+            if [ "$observer_status" -ne 0 ]; then status=1; fi
+          }
           while IFS= read -r check; do
             index=$((index + 1))
             echo "Starting $check"
+            observe_holders before
             printf 'running\n' > "remote-source-verification/check-$index.status"
             # test:run executes all groups serially. Recorded server durations
             # alone exceed 85 minutes; ordinary CI distributes them across shards.
@@ -758,6 +781,7 @@ jobs:
             printf '%s\t%s\n' "$check_status" "$check" >> remote-source-verification/check-status.tsv
             if [ "$check_status" -ne 0 ]; then status=1; fi
             echo "Finished $check (exit $check_status)"
+            observe_holders after
           done < remote-source-verification/commands.txt
           exit "$status"
       - name: Audit source and lock closure even on check failure
diff --git a/scripts/ci/source-observer/executable_holders.py b/scripts/ci/source-observer/executable_holders.py
new file mode 100644
index 00000000000..8afabe70aac
--- /dev/null
+++ b/scripts/ci/source-observer/executable_holders.py
@@ -0,0 +1,87 @@
+"""Read-only Linux evidence for the exact staged Runner executable; never signal."""
+import argparse
+from datetime import datetime, timezone
+import json
+import os
+from pathlib import Path
+import stat
+import time
+
+
+def identity(path):
+    value = path.stat()
+    return {"dev": str(value.st_dev), "ino": str(value.st_ino),
+            "size": value.st_size, "mode": stat.S_IMODE(value.st_mode)}
+
+
+def process_identity(path):
+    # comm may contain spaces or parentheses. Do not retain it, argv, or env.
+    value = (path / "stat").read_text()
+    fields = value[value.rindex(")") + 2:].split()
+    return {"pid": int(path.name), "state": fields[0], "ppid": int(fields[1]),
+            "processGroup": int(fields[2]), "startTimeTicks": fields[19]}
+
+
+def inspect(target, proc=Path("/proc"), max_pids=32768, seconds=8):
+    target = Path(os.path.abspath(target))
+    begin = time.monotonic()
+    result = {"schema": "paperclip.exact-executable-holders/v1",
+              "observedAt": datetime.now(timezone.utc).isoformat(),
+              "target": str(target), "targetBefore": None, "holders": [],
+              "permissionDenied": 0, "racedMatches": 0, "scanned": 0,
+              "complete": True, "signalsSent": 0}
+    try:
+        if target.is_symlink() or not stat.S_ISREG(target.stat().st_mode):
+            raise ValueError("Staged executable is not a regular non-symlink file")
+        result["targetBefore"] = identity(target)
+    except FileNotFoundError:
+        pass  # The first typecheck has not staged the daemon yet.
+    for entry in proc.iterdir():
+        if not entry.name.isdecimal():
+            continue
+        if result["scanned"] >= max_pids or time.monotonic() - begin >= seconds:
+            result.update(complete=False, stopReason="bounded_scan_limit")
+            break
+        result["scanned"] += 1
+        matched = False
+        try:
+            exe = entry / "exe"
+            link = os.readlink(exe)
+            executable = identity(exe)
+            pinned = result["targetBefore"]
+            by_inode = bool(pinned and all(executable[k] == pinned[k] for k in ("dev", "ino")))
+            by_path = link in (str(target), str(target) + " (deleted)")
+            if not (by_inode or by_path):
+                continue
+            matched = True
+            before = process_identity(entry)
+            after = process_identity(entry)
+            if before != after or identity(exe) != executable or os.readlink(exe) != link:
+                result["racedMatches"] += 1
+                continue
+            result["holders"].append({**before, "executable": executable,
+                                      "matchesTargetInode": by_inode,
+                                      "matchesTargetPath": by_path,
+                                      "deletedExecutable": link.endswith(" (deleted)")})
+        except FileNotFoundError:
+            if matched:
+                result["racedMatches"] += 1
+        except PermissionError:
+            result["permissionDenied"] += 1
+    try:
+        result["targetAfter"] = identity(target)
+    except FileNotFoundError:
+        result["targetAfter"] = None
+    result["targetChangedDuringScan"] = result["targetBefore"] != result["targetAfter"]
+    result["complete"] = (result["complete"] and not result["permissionDenied"]
+                          and not result["racedMatches"] and not result["targetChangedDuringScan"])
+    result["holders"].sort(key=lambda row: row["pid"])
+    result["elapsedSeconds"] = round(time.monotonic() - begin, 6)
+    return result
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--target", type=Path, required=True)
+    args = parser.parse_args()
+    print(json.dumps(inspect(args.target), sort_keys=True))
diff --git a/scripts/ci/source-observer/test_executable_holders.py b/scripts/ci/source-observer/test_executable_holders.py
new file mode 100644
index 00000000000..c9dfc7d423f
--- /dev/null
+++ b/scripts/ci/source-observer/test_executable_holders.py
@@ -0,0 +1,113 @@
+import json
+from pathlib import Path
+import tempfile
+import unittest
+from unittest.mock import patch
+
+import executable_holders as observer
+
+
+class HolderTests(unittest.TestCase):
+    def setUp(self):
+        self.temp = tempfile.TemporaryDirectory()
+        self.addCleanup(self.temp.cleanup)
+        self.root = Path(self.temp.name)
+        self.proc = self.root / "proc"
+        self.proc.mkdir()
+        self.target = self.root / "paperclip-runnerd"
+        self.target.write_bytes(b"exact daemon")
+
+    def process(self, pid, executable):
+        root = self.proc / str(pid)
+        root.mkdir()
+        (root / "exe").symlink_to(executable)
+        # Include malicious-looking comm; it must never appear in output.
+        (root / "stat").write_text(f"{pid} (secret ) argv) S 7 8 " + "0 " * 16 + "12345 0")
+        (root / "environ").write_text("DO_NOT_READ_SECRET")
+        (root / "cmdline").write_text("DO_NOT_READ_SECRET")
+        return root
+
+    def inspect(self, **kw):
+        return observer.inspect(self.target, self.proc, **kw)
+
+    def test_exact_inode_and_only_numeric_process_fields(self):
+        self.process(12, self.target)
+        other = self.root / "other"
+        other.write_bytes(b"foreign")
+        self.process(13, other)
+        result = self.inspect()
+        self.assertTrue(result["complete"])
+        self.assertEqual([r["pid"] for r in result["holders"]], [12])
+        self.assertEqual(result["holders"][0]["startTimeTicks"], "12345")
+        self.assertNotIn("secret", json.dumps(result).lower())
+        self.assertEqual(result["signalsSent"], 0)
+
+    def test_inode_alias_is_still_holder(self):
+        alias = self.root / "alias"
+        alias.hardlink_to(self.target)
+        self.process(12, alias)
+        row = self.inspect()["holders"][0]
+        self.assertTrue(row["matchesTargetInode"])
+        self.assertFalse(row["matchesTargetPath"])
+
+    def test_deleted_path_preserved_even_after_replacement(self):
+        deleted = Path(str(self.target) + " (deleted)")
+        deleted.write_bytes(b"old")
+        self.process(12, deleted)
+        row = self.inspect()["holders"][0]
+        self.assertTrue(row["matchesTargetPath"])
+        self.assertTrue(row["deletedExecutable"])
+        self.assertFalse(row["matchesTargetInode"])
+
+    def test_target_not_built_yet(self):
+        self.target.unlink()
+        self.assertIsNone(self.inspect()["targetBefore"])
+
+    def test_symlink_target_rejected(self):
+        self.target.unlink()
+        self.target.symlink_to(self.root / "foreign")
+        with self.assertRaisesRegex(ValueError, "non-symlink"):
+            self.inspect()
+
+    def test_bounded_scan_is_explicitly_incomplete(self):
+        self.process(12, self.target)
+        result = self.inspect(max_pids=0)
+        self.assertFalse(result["complete"])
+        self.assertEqual(result["stopReason"], "bounded_scan_limit")
+
+    def test_process_identity_race_is_not_attested(self):
+        self.process(12, self.target)
+        with patch.object(observer, "process_identity", side_effect=[{"pid": 12}, {"pid": 99}]):
+            result = self.inspect()
+        self.assertFalse(result["complete"])
+        self.assertEqual(result["holders"], [])
+        self.assertEqual(result["racedMatches"], 1)
+
+    def test_permission_denial_is_explicitly_incomplete(self):
+        self.process(12, self.target)
+        with patch.object(observer.os, "readlink", side_effect=PermissionError):
+            result = self.inspect()
+        self.assertFalse(result["complete"])
+        self.assertEqual(result["permissionDenied"], 1)
+
+    def test_target_replacement_during_scan_is_incomplete(self):
+        real = observer.identity
+        calls = 0
+
+        def changed(path):
+            nonlocal calls
+            row = real(path)
+            if path == self.target:
+                calls += 1
+                if calls == 2:
+                    row["ino"] = "replacement"
+            return row
+
+        with patch.object(observer, "identity", side_effect=changed):
+            result = self.inspect()
+        self.assertTrue(result["targetChangedDuringScan"])
+        self.assertFalse(result["complete"])
+
+
+if __name__ == "__main__":
+    unittest.main()