diff --git a/docs/bwrap-runtime.md b/docs/bwrap-runtime.md
index 2cef21f..8561eaa 100644
--- a/docs/bwrap-runtime.md
+++ b/docs/bwrap-runtime.md
@@ -237,10 +237,15 @@ owner discrepancy for bwrap. It is not a claim that every remote backend's exter
 hosts/templates/tools are packaged or admitted. The ephemeral Messages binding may
 select an exact runtime path/digest; usual overlap and default-deny checks apply.
 
-Required `make check`: lint clean, 201 tests passed. Rein's
+Required `make check`: lint clean, 205 tests passed. Rein's
 `scripts/prove-metered-runtime.py` consumes the candidate to test installed imports,
 packaged definitions, explicit one-cycle bootstrap, actual pinned CLI/metered stream,
 insufficient-capacity refusal and teardown against fixtures. The resulting receipt
 belongs to `prj-helixforge-factory/evidence/2026-09-09-owner-bootstrap.json`.
 Production installation and credential-holder/empty-egress profile/placement admission
 remain SAND-WP-0015-T04 and HFACT-WP-0001-T03/T04; no prior profile is promoted.
+
+The first standalone candidate exposed a stale cached local wheel despite current
+Git metadata. Owner builds now refresh all local distributions and compare every
+installed package source/definition file with its tracked source; stale, missing or
+extra files refuse the build. Four content-conformance regressions cover that gap.
diff --git a/scripts/build-rein-runtime.py b/scripts/build-rein-runtime.py
index bbcd071..615f222 100644
--- a/scripts/build-rein-runtime.py
+++ b/scripts/build-rein-runtime.py
@@ -43,6 +43,33 @@ def install_claude(output: Path, source: Path, sha256: str, version: str) -> dic
             "expected_version": version, "source": str(source)}
 
 
+def verify_source_files(site: Path, mappings: list[tuple[Path, str, str]]) -> dict:
+    """Refuse stale/missing/extra package contents even when versions match."""
+    expected = {}
+    for source, prefix, destination in mappings:
+        tracked = checked(["git", "-C", str(source), "ls-files", prefix]).splitlines()
+        if not tracked:
+            raise ValueError("owner package source mapping is empty")
+        for name in tracked:
+            relative = Path(destination) / Path(name).relative_to(prefix)
+            wanted = hashlib.sha256((source / name).read_bytes()).hexdigest()
+            installed = site / relative
+            if (not installed.is_file() or installed.is_symlink()
+                    or hashlib.sha256(installed.read_bytes()).hexdigest() != wanted):
+                raise ValueError(f"owner package content mismatch: {relative}")
+            expected[relative.as_posix()] = wanted
+    actual = set()
+    for package in {Path(name).parts[0] for name in expected}:
+        for path in (site / package).rglob("*"):
+            if path.is_file() and "__pycache__" not in path.parts:
+                actual.add(path.relative_to(site).as_posix())
+    if actual != set(expected):
+        raise ValueError("owner package has unexpected installed files")
+    return {"files_verified": len(expected), "manifest_sha256": hashlib.sha256(
+        json.dumps(expected, sort_keys=True, separators=(",", ":")).encode()
+    ).hexdigest()}
+
+
 def build(output: Path, rein_source: Path, llm_source: Path,
           claude_binary: Path | None = None, claude_sha256: str | None = None,
           claude_version: str | None = None, *, owner_runtime: bool = False) -> dict:
@@ -68,8 +95,10 @@ def build(output: Path, rein_source: Path, llm_source: Path,
     output.mkdir(parents=True, exist_ok=False)
     checked(["/usr/bin/python3", "-m", "venv", "--copies", "--without-pip", str(output)])
     if owner_runtime:
+        refresh = [arg for name in revisions for arg in ("--refresh-package", name)]
         checked(["uv", "sync", "--project", str(rein_source), "--frozen", "--no-editable",
-                 "--no-dev", "--extra", "glas", "--extra", "llm", "--python", "/usr/bin/python3"],
+                 "--no-dev", "--extra", "glas", "--extra", "llm", "--python", "/usr/bin/python3",
+                 *refresh],
                 env={**os.environ, "UV_PROJECT_ENVIRONMENT": str(output)})
     else:
         checked(["uv", "pip", "install", "--python", str(output / "bin/python3"),
@@ -93,6 +122,23 @@ def build(output: Path, rein_source: Path, llm_source: Path,
         metadata["claude"] = install_claude(output, claude_binary, claude_sha256, claude_version)
     metadata["source_revisions"] = revisions
     if owner_runtime:
+        lock = json.loads((rein_source / "deploy/runtime-contract-lock.json").read_text())
+        sources = {x["distribution"]: (rein_source / x["source"]).resolve()
+                   for x in lock["dependencies"]}
+        site = Path(checked([str(output / "bin/python3"), "-I", "-B", "-c",
+                             "import sysconfig; print(sysconfig.get_path('purelib'))"]))
+        if not site.resolve().is_relative_to(output.resolve()):
+            raise ValueError("owner site-packages is outside artifact")
+        metadata["source_contents"] = verify_source_files(site, [
+            (rein_source, "rein_aharness", "rein_aharness"),
+            (sources["llm-connect"], "llm_connect", "llm_connect"),
+            (sources["glas-harness"], "src/glas_harness", "glas_harness"),
+            (sources["glas-harness"], "profiles", "glas_harness/data/profiles"),
+            (sources["glas-harness"], "registry/reins", "glas_harness/data/reins"),
+            (sources["sandboxer"], "src/sandboxer", "sandboxer"),
+            (sources["sandboxer"], "profiles", "sandboxer/data/profiles"),
+            (sources["sandboxer"], "extensions", "sandboxer/data/extensions"),
+        ])
         metadata["owner_runtime"] = True
         metadata["runtime_contract"] = lock_report
         metadata["uv_lock_sha256"] = hashlib.sha256(
diff --git a/tests/test_runtime_builder.py b/tests/test_runtime_builder.py
index 15717d0..c4bb5a0 100644
--- a/tests/test_runtime_builder.py
+++ b/tests/test_runtime_builder.py
@@ -69,3 +69,30 @@ def test_owner_build_requires_matching_sibling_lock_before_output(tmp_path, monk
     with pytest.raises(ValueError, match="does not match"):
         builder.build(output, rein, llm, owner_runtime=True)
     assert not output.exists()
+
+
+@pytest.mark.parametrize("change", [None, "stale", "missing", "extra"])
+def test_installed_package_contents_must_match_committed_source(tmp_path, change):
+    import subprocess
+    source = tmp_path / "source"
+    package = source / "fixture"
+    package.mkdir(parents=True)
+    (package / "__init__.py").write_text("VERSION = 2\n")
+    subprocess.run(["git", "init", "-q", str(source)], check=True)
+    subprocess.run(["git", "-C", str(source), "add", "fixture"], check=True)
+    site = tmp_path / "site"
+    installed = site / "fixture"
+    installed.mkdir(parents=True)
+    (installed / "__init__.py").write_text("VERSION = 2\n")
+    if change == "stale":
+        (installed / "__init__.py").write_text("VERSION = 1\n")
+    elif change == "missing":
+        (installed / "__init__.py").unlink()
+    elif change == "extra":
+        (installed / "retired.py").write_text("old = True\n")
+    if change:
+        with pytest.raises(ValueError, match="owner package"):
+            builder.verify_source_files(site, [(source, "fixture", "fixture")])
+    else:
+        result = builder.verify_source_files(site, [(source, "fixture", "fixture")])
+        assert result["files_verified"] == 1
diff --git a/workplans/SAND-WP-0015-bwrap-runtime-and-private-state.md b/workplans/SAND-WP-0015-bwrap-runtime-and-private-state.md
index 1751c5a..24ec0b6 100644
--- a/workplans/SAND-WP-0015-bwrap-runtime-and-private-state.md
+++ b/workplans/SAND-WP-0015-bwrap-runtime-and-private-state.md
@@ -268,7 +268,7 @@ with non-editable installation and recorded lock/source/package pins. Sand-boxer
 wheels now carry their profile and extension definitions, fixing a bwrap owner
 failure that source-checkout tests could hide. The trusted Messages binding can
 select the digest-pinned runtime without adding an API or profile override.
-`make check`: lint clean, 201 passed. Existing standalone workload builds remain
+`make check`: lint clean, 205 passed. Existing standalone workload builds remain
 supported. See docs/bwrap-runtime.md and rein's docs/owner-bootstrap.md.
 
 The project's `evidence/2026-09-09-owner-bootstrap.json` records the actual candidate
@@ -276,3 +276,8 @@ build and isolated installed-interpreter/CLI proof. T04 remains wait for accepte
 credential-to-owner delivery, current protected installation and Railiance placement,
 provider compatibility and G0. Source packaging does not reopen completed T01-T03,
 T05-T06, broaden the old CCRs or activate the previously installed 2.1.263 artifact.
+
+The first standalone candidate exposed a stale cached local wheel despite current
+Git metadata. Owner builds now refresh all local distributions and compare every
+installed package source/definition file with its tracked source; stale, missing or
+extra files refuse the build. Four content-conformance regressions cover that gap.