diff --git a/.github/workflows/validate.yml b/.github/workflows/validate.yml
index 9291a3e..075fc61 100644
--- a/.github/workflows/validate.yml
+++ b/.github/workflows/validate.yml
@@ -26,6 +26,8 @@ jobs:
         run: |
           pip install pytest
           python -m pytest tests/test_validate_integrations.py -q
+      - name: Test composite action dependency paths
+        run: python -m pytest tests/test_composite_action_paths.py -q
       - name: Test conditional schema rules
         run: |
           pip install pytest
diff --git a/copilot/action.yml b/copilot/action.yml
index 0f970a6..9849337 100644
--- a/copilot/action.yml
+++ b/copilot/action.yml
@@ -39,10 +39,10 @@ runs:
   using: composite
   steps:
     # The engine imports agentrust-capture-core, which has no dependencies of its
-    # own, so this stays one small install rather than a tree. Pinned to a minor
-    # range so a core release cannot silently change what this check measures.
+    # own, so this stays one small install rather than a tree. The core ships in
+    # this action checkout, binding it to the same referenced revision.
     - shell: bash
-      run: pip install --quiet "$GITHUB_WORKSPACE/packages/agentrust-capture-core"
+      run: pip install --quiet "${{ github.action_path }}/../packages/agentrust-capture-core"
 
     - id: check
       shell: bash
diff --git a/cursor/action.yml b/cursor/action.yml
index 80f9611..b0bc4df 100644
--- a/cursor/action.yml
+++ b/cursor/action.yml
@@ -39,7 +39,7 @@ runs:
   using: composite
   steps:
     - shell: bash
-      run: pip install --quiet "$GITHUB_WORKSPACE/packages/agentrust-capture-core"
+      run: pip install --quiet "${{ github.action_path }}/../packages/agentrust-capture-core"
 
     - id: check
       shell: bash
diff --git a/gemini-cli/action.yml b/gemini-cli/action.yml
index c0d56ab..66f1fc1 100644
--- a/gemini-cli/action.yml
+++ b/gemini-cli/action.yml
@@ -39,7 +39,7 @@ runs:
   using: composite
   steps:
     - shell: bash
-      run: pip install --quiet "$GITHUB_WORKSPACE/packages/agentrust-capture-core"
+      run: pip install --quiet "${{ github.action_path }}/../packages/agentrust-capture-core"
 
     - id: check
       shell: bash
diff --git a/tests/test_composite_action_paths.py b/tests/test_composite_action_paths.py
new file mode 100644
index 0000000..ba77d5f
--- /dev/null
+++ b/tests/test_composite_action_paths.py
@@ -0,0 +1,55 @@
+from __future__ import annotations
+
+import shlex
+import shutil
+from pathlib import Path
+
+import pytest
+import yaml
+
+
+REPOSITORY_ROOT = Path(__file__).resolve().parent.parent
+ACTION_NAMES = ("copilot", "cursor", "gemini-cli", "windsurf")
+CAPTURE_CORE = Path("packages/agentrust-capture-core")
+
+
+@pytest.mark.parametrize("action_name", ACTION_NAMES)
+def test_capture_core_is_resolved_from_the_action_checkout(
+    action_name: str, tmp_path: Path
+) -> None:
+    """A reusable action must not resolve its code from the caller's checkout."""
+    action_store = tmp_path / "_actions" / "agentrust-io" / "integrations" / "ref"
+    action_path = action_store / action_name
+    consumer_workspace = tmp_path / "consumer"
+    action_core = action_store / CAPTURE_CORE
+    consumer_core = consumer_workspace / CAPTURE_CORE
+
+    # Model a remote action checkout and the consumer repository as separate
+    # trees. A local ``uses: ./<action>`` smoke test puts both under
+    # GITHUB_WORKSPACE and therefore cannot catch this boundary error.
+    action_path.mkdir(parents=True)
+    shutil.copytree(REPOSITORY_ROOT / CAPTURE_CORE, action_core)
+    consumer_core.mkdir(parents=True)
+
+    document = yaml.safe_load(
+        (REPOSITORY_ROOT / action_name / "action.yml").read_text(encoding="utf-8")
+    )
+    install_commands = [
+        step["run"]
+        for step in document["runs"]["steps"]
+        if "agentrust-capture-core" in step.get("run", "")
+    ]
+
+    assert len(install_commands) == 1
+    command = install_commands[0]
+    assert "$GITHUB_WORKSPACE" not in command
+
+    rendered = command.replace("${{ github.action_path }}", str(action_path))
+    arguments = shlex.split(rendered)
+
+    assert arguments[:3] == ["pip", "install", "--quiet"]
+    assert len(arguments) == 4
+    resolved_core = Path(arguments[3]).resolve()
+    assert resolved_core == action_core.resolve()
+    assert resolved_core != consumer_core.resolve()
+    assert (resolved_core / "pyproject.toml").is_file()
diff --git a/windsurf/action.yml b/windsurf/action.yml
index b6ed9e8..888ec6e 100644
--- a/windsurf/action.yml
+++ b/windsurf/action.yml
@@ -38,7 +38,7 @@ runs:
   using: composite
   steps:
     - shell: bash
-      run: pip install --quiet "$GITHUB_WORKSPACE/packages/agentrust-capture-core"
+      run: pip install --quiet "${{ github.action_path }}/../packages/agentrust-capture-core"
 
     - id: check
       shell: bash