diff --git a/.dockerignore b/.dockerignore
index b127506..5ac7fc8 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -1,14 +1,11 @@
-.git
-.github
-.venv
-.pytest_cache
-.ruff_cache
-.mypy_cache
-__pycache__
-*.py[cod]
-*.egg-info
-build
-dist
-htmlcov
-.coverage
-test-results.xml
+# Fail-closed allowlist for the Planfile fleet-runner build context.
+*
+!.dockerignore
+!Dockerfile
+!README.md
+!pyproject.toml
+!uv.lock
+!planfile/
+!planfile/**
+!scripts/
+!scripts/docker-entrypoint.sh
diff --git a/Dockerfile b/Dockerfile
index 1228fbc..9ce112e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,28 +1,25 @@
 # Planfile CI/CD Runner Docker Image
-FROM python:3.11-slim
+# uv 0.11.28 and Python 3.12.14 are selected by immutable multi-platform
+# manifest digests. Keep the human-readable versions in this comment only.
+FROM ghcr.io/astral-sh/uv@sha256:0f36cb9361a3346885ca3677e3767016687b5a170c1a6b88465ec14aefec90aa AS uv
+FROM python@sha256:782412e85d0f0984994c290652577d4018aff08145c85b262bb63dc0c7522254 AS runtime
+
+COPY --from=uv /uv /uvx /bin/
 
 # Install system dependencies
-RUN apt-get update && apt-get install -y \
+RUN apt-get update && apt-get install -y --no-install-recommends \
     git \
-    curl \
     jq \
     && rm -rf /var/lib/apt/lists/*
 
-# Install Ollama for local LLM support
-RUN curl -fsSL https://ollama.ai/install.sh | sh
-
 # Set working directory
 WORKDIR /app
 
-# Copy requirements
-COPY requirements.txt .
-RUN pip install --no-cache-dir -r requirements.txt
-
-# Install Planfile with all integrations
-RUN pip install --no-cache-dir planfile[all]
-
-# Install LLX
-RUN pip install --no-cache-dir llx
+# Install the local package and all runner integrations from the committed,
+# hash-bearing lockfile. Frozen mode refuses to resolve or rewrite anything.
+COPY pyproject.toml uv.lock README.md ./
+COPY planfile/ ./planfile/
+RUN uv sync --frozen --no-dev --extra all --no-editable
 
 # Copy entrypoint script
 COPY scripts/docker-entrypoint.sh /usr/local/bin/
@@ -35,9 +32,8 @@ RUN mkdir -p /workspace /app/results
 ENV PYTHONPATH=/app
 ENV WORKSPACE=/workspace
 ENV RESULTS_DIR=/app/results
-
-# Expose port for Ollama
-EXPOSE 11434
+ENV VIRTUAL_ENV=/app/.venv
+ENV PATH="/app/.venv/bin:${PATH}"
 
 # Health check
 HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
diff --git a/docker-compose.yml b/docker-compose.yml
index fa8e105..6bb69ae 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -12,10 +12,6 @@ services:
       - MAX_ITERATIONS=5
       - AUTO_FIX=false
       
-      # Ollama settings
-      - ENABLE_OLLAMA=true
-      - OLLAMA_MODEL=qwen2.5:3b
-      
       # Strategy file (mount or copy)
       - STRATEGY_FILE=/app/planfile.yaml
       
@@ -56,9 +52,6 @@ services:
       # Mount git config if needed
       - ~/.gitconfig:/root/.gitconfig:ro
     
-    ports:
-      - "11434:11434"  # Ollama API
-    
     networks:
       - planfile
     
diff --git a/scripts/docker-entrypoint.sh b/scripts/docker-entrypoint.sh
index 8733ca3..cdbe876 100644
--- a/scripts/docker-entrypoint.sh
+++ b/scripts/docker-entrypoint.sh
@@ -10,17 +10,12 @@ NC='\033[0m' # No Color
 echo -e "${GREEN}🚀 Planfile CI/CD Runner${NC}"
 echo "=============================="
 
-# Start Ollama in background if enabled
-if [ "$ENABLE_OLLAMA" = "true" ]; then
-    echo -e "${YELLOW}🤖 Starting Ollama...${NC}"
-    ollama serve &
-    sleep 5
-    
-    # Pull default model if specified
-    if [ -n "$OLLAMA_MODEL" ]; then
-        echo -e "${YELLOW}📥 Pulling model: $OLLAMA_MODEL${NC}"
-        ollama pull "$OLLAMA_MODEL"
-    fi
+# The fleet runner no longer downloads or embeds Ollama. Call an external,
+# independently managed Ollama endpoint through the normal provider settings.
+if [ "${ENABLE_OLLAMA:-false}" = "true" ]; then
+    echo -e "${RED}❌ Embedded Ollama is not part of the locked runner image.${NC}" >&2
+    echo "Configure an external Ollama endpoint instead." >&2
+    exit 2
 fi
 
 # Check required environment variables
diff --git a/tests/test_docker_supply_chain.py b/tests/test_docker_supply_chain.py
new file mode 100644
index 0000000..c548762
--- /dev/null
+++ b/tests/test_docker_supply_chain.py
@@ -0,0 +1,44 @@
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+DOCKERFILE = ROOT / "Dockerfile"
+DIGEST_FROM = re.compile(r"^FROM\s+\S+@sha256:[0-9a-f]{64}(?:\s+AS\s+\S+)?$", re.MULTILINE)
+
+
+def test_every_runner_stage_uses_an_immutable_image_digest() -> None:
+    text = DOCKERFILE.read_text(encoding="utf-8")
+    from_lines = [line for line in text.splitlines() if line.startswith("FROM ")]
+
+    assert from_lines
+    assert all(DIGEST_FROM.fullmatch(line) for line in from_lines)
+
+
+def test_runner_uses_only_frozen_python_resolution() -> None:
+    text = DOCKERFILE.read_text(encoding="utf-8")
+
+    assert "uv sync --frozen --no-dev --extra all --no-editable" in text
+    assert "COPY pyproject.toml uv.lock README.md ./" in text
+    assert "pip install" not in text
+    assert "install.sh" not in text
+    assert "curl " not in text
+
+
+def test_docker_context_is_an_explicit_allowlist() -> None:
+    entries = (ROOT / ".dockerignore").read_text(encoding="utf-8").splitlines()
+    active = [line for line in entries if line and not line.startswith("#")]
+
+    assert active[0] == "*"
+    assert set(active[1:]) == {
+        "!.dockerignore",
+        "!Dockerfile",
+        "!README.md",
+        "!pyproject.toml",
+        "!uv.lock",
+        "!planfile/",
+        "!planfile/**",
+        "!scripts/",
+        "!scripts/docker-entrypoint.sh",
+    }