diff --git a/.github/workflows/python-tests.yml b/.github/workflows/python-tests.yml
index 4b413eb057..2d7f182664 100644
--- a/.github/workflows/python-tests.yml
+++ b/.github/workflows/python-tests.yml
@@ -838,6 +838,11 @@ jobs:
       - name: Verify native Windows test Python discovery
         run: node --no-warnings --experimental-strip-types --test tests/control_plane_ts/test_python_runtime.test.ts
 
+      - name: Qualify the canary plan's repository path rendering
+        run: >-
+          python -m pytest -q
+          tests/canary/test_repository_root.py::test_plan_renders_repository_paths_in_canonical_posix_form
+
       - name: Run native Windows lifecycle tests
         run: >-
           python -m pytest -q
diff --git a/loopx/canary/planner.py b/loopx/canary/planner.py
index 68d7fd7bbc..4a180c1022 100644
--- a/loopx/canary/planner.py
+++ b/loopx/canary/planner.py
@@ -1387,7 +1387,7 @@ def _read_catalog(catalog_path: Path | None = None) -> tuple[Path, str]:
 
 def _display_path(path: Path) -> str:
     try:
-        return str(path.relative_to(REPO_ROOT))
+        return path.relative_to(REPO_ROOT).as_posix()
     except ValueError:
         return str(path)
 
diff --git a/loopx/canary/premerge.py b/loopx/canary/premerge.py
index 24d6be33d6..ee7b4b66c3 100644
--- a/loopx/canary/premerge.py
+++ b/loopx/canary/premerge.py
@@ -168,7 +168,7 @@ def _public_boundary_changed_files_run(
     display_paths: list[str] = []
     for path in existing_paths:
         try:
-            display_paths.append(str(path.relative_to(repo_root.resolve())))
+            display_paths.append(path.relative_to(repo_root.resolve()).as_posix())
         except ValueError:
             display_paths.append(str(path))
     display_argv = ["loopx", "check"]
@@ -345,7 +345,7 @@ def _display_argv(argv: list[str], *, repo_root: Path = REPO_ROOT) -> list[str]:
     for index, value in enumerate(displayed[1:], start=1):
         path = Path(value)
         try:
-            displayed[index] = str(path.resolve().relative_to(repo_root.resolve()))
+            displayed[index] = path.resolve().relative_to(repo_root.resolve()).as_posix()
         except (OSError, ValueError):
             displayed[index] = value
     return displayed
diff --git a/loopx/canary/runner.py b/loopx/canary/runner.py
index b6a4fd6f11..f376a64b9a 100644
--- a/loopx/canary/runner.py
+++ b/loopx/canary/runner.py
@@ -152,7 +152,7 @@ def normalize_canary_command(command: str, repo_root: Path | None = None) -> dic
         "argv": argv,
         "display_argv": _display_argv(argv, repo_root=repo_root),
         "injected_args": injected_args,
-        "script": str(script.relative_to(repo_root)),
+        "script": script.relative_to(repo_root).as_posix(),
     }
 
 
@@ -164,7 +164,7 @@ def _display_argv(argv: list[str], repo_root: Path | None = None) -> list[str]:
     for index, value in enumerate(displayed[1:], start=1):
         path = Path(value)
         if path.is_absolute() and _is_relative_to(path.resolve(), repo_root.resolve()):
-            displayed[index] = str(path.resolve().relative_to(repo_root.resolve()))
+            displayed[index] = path.resolve().relative_to(repo_root.resolve()).as_posix()
     return displayed
 
 
diff --git a/tests/canary/test_repository_root.py b/tests/canary/test_repository_root.py
index 10d822b619..22b0dced34 100644
--- a/tests/canary/test_repository_root.py
+++ b/tests/canary/test_repository_root.py
@@ -53,6 +53,58 @@ def test_premerge_uses_selected_checkout_for_nested_plans(tmp_path):
             assert Path(check["normalized"]["argv"][1]).is_relative_to(repo / "examples")
 
 
+def _selected_checks(payload: dict) -> list[dict]:
+    checks = [check for check in payload.get("selected_checks") or [] if isinstance(check, dict)]
+    for section in ("catalog_run", "risk_profile_run"):
+        run = payload.get(section)
+        if isinstance(run, dict):
+            checks.extend(check for check in run.get("selected_checks") or [] if isinstance(check, dict))
+    return checks
+
+
+def _assert_canonical_path(rendered: str) -> None:
+    """A repository-relative path keeps the canonical POSIX spelling.
+
+    ``PurePosixPath`` would leave a host separator untouched, so the stray
+    backslash is rejected explicitly rather than through a normalization that
+    already agrees with the value.
+    """
+
+    assert "\\" not in rendered, rendered
+    assert rendered == Path(rendered).as_posix(), rendered
+
+
+def test_plan_renders_repository_paths_in_canonical_posix_form(tmp_path):
+    """A plan's repository-relative paths keep the canonical spelling everywhere.
+
+    The catalog, the suite checks, the shipped contract smokes and the public
+    docs all declare ``python3 examples/<...>.py``. Rendering the same path with
+    the host separator makes one check read differently per host, which fails
+    those smokes on Windows and records host-dependent premerge evidence.
+    """
+
+    repo = _checkout(tmp_path / "repo")
+    suite = build_canary_smoke_suite_run(repo_root=repo)
+    gate = build_premerge_validation_gate(
+        repo_root=repo, changed_files=["loopx/canary/runner.py"],
+        base_ref="HEAD", execute=False,
+    )
+    checks = _selected_checks(suite) + _selected_checks(gate)
+    rendered = []
+    for check in checks:
+        normalized = check.get("normalized") or {}
+        if normalized.get("ok") is not True:
+            continue
+        rendered.append(str(normalized.get("script") or ""))
+        rendered.extend(
+            str(token) for token in normalized.get("display_argv") or [] if "examples" in str(token)
+        )
+    commands = [str(item) for item in gate["validation_summary"]["selected_commands"]]
+    assert rendered and commands
+    for item in [*rendered, *commands]:
+        _assert_canonical_path(item)
+
+
 @pytest.mark.parametrize("jobs", [1, 2])
 def test_target_checkout_write_guard_detects_and_restores(tmp_path, jobs):
     repo = _checkout(tmp_path / "repo", mutate=True)