diff --git a/.devcontainer/Dockerfile b/.devcontainer/Dockerfile
new file mode 100644
index 0000000..07aa457
--- /dev/null
+++ b/.devcontainer/Dockerfile
@@ -0,0 +1,49 @@
+FROM mcr.microsoft.com/devcontainers/base:trixie
+
+# Version pins — change these ARGs and rebuild to switch versions.
+ARG PYTHON_VERSION=3.13
+ARG NODE_VERSION=lts
+
+ENV PYENV_ROOT=/usr/local/pyenv \
+    NVM_DIR=/usr/local/nvm
+
+# The padawan-fw runc shim bind-mounts a mode-0700 tmpdir over /etc/ssl/certs in every
+# container it starts. Each RUN step opens with chmod 755 /etc/ssl/certs so that both
+# root and the non-root vscode user can reach the cert bundle for TLS.
+
+# Build dependencies needed by pyenv to compile Python from source.
+RUN chmod 755 /etc/ssl/certs \
+    && apt-get update \
+    && apt-get install -y --no-install-recommends \
+         build-essential libssl-dev zlib1g-dev libbz2-dev libreadline-dev \
+         libsqlite3-dev libncursesw5-dev xz-utils tk-dev libxml2-dev \
+         libxmlsec1-dev libffi-dev liblzma-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install pyenv to /usr/local/pyenv and compile the pinned Python version.
+# Direct git clone avoids the pyenv-installer script's Launchpad/GitHub API calls
+# and makes the install reproducible.
+RUN chmod 755 /etc/ssl/certs \
+    && git clone https://github.com/pyenv/pyenv.git ${PYENV_ROOT} \
+    && ${PYENV_ROOT}/bin/pyenv install ${PYTHON_VERSION} \
+    && ${PYENV_ROOT}/bin/pyenv global ${PYTHON_VERSION} \
+    && chown -R root:root ${PYENV_ROOT} \
+    && chmod -R a+rX ${PYENV_ROOT} \
+    && ln -sf "$(${PYENV_ROOT}/bin/pyenv which python3)" /usr/local/bin/python3 \
+    && ln -sf "$(${PYENV_ROOT}/bin/pyenv which pip3)"    /usr/local/bin/pip3 \
+    && ln -sf "$(${PYENV_ROOT}/bin/pyenv which pip3)"    /usr/local/bin/pip
+
+# Install nvm to /usr/local/nvm and install the pinned Node version.
+RUN chmod 755 /etc/ssl/certs \
+    && mkdir -p "${NVM_DIR}" \
+    && curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.3/install.sh \
+         | NVM_DIR="${NVM_DIR}" bash \
+    && . "${NVM_DIR}/nvm.sh" \
+    && nvm install "${NODE_VERSION}" \
+    && nvm alias default "${NODE_VERSION}" \
+    && NODE_BIN="$(nvm which default)" \
+    && chown -R root:root "${NVM_DIR}" \
+    && chmod -R a+rX "${NVM_DIR}" \
+    && ln -sf "${NODE_BIN}"                      /usr/local/bin/node \
+    && ln -sf "$(dirname "${NODE_BIN}")/npm"     /usr/local/bin/npm \
+    && ln -sf "$(dirname "${NODE_BIN}")/npx"     /usr/local/bin/npx
diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
index d21bba3..324d17d 100644
--- a/.devcontainer/devcontainer.json
+++ b/.devcontainer/devcontainer.json
@@ -3,14 +3,8 @@
   "dockerComposeFile": "docker-compose.yml",
   "service": "app",
   "workspaceFolder": "/workspaces/repro",
-  "features": {
-    "ghcr.io/devcontainers/features/node:1": {
-      "version": "22"
-    },
-    "ghcr.io/devcontainers/features/python:1": {
-      "version": "3.13"
-    }
-  },
   "onCreateCommand": "./.devcontainer/on-create.sh",
-  "updateContentCommand": "./.devcontainer/update-content.sh"
+  "updateContentCommand": "./.devcontainer/update-content.sh",
+  "postCreateCommand": "./.devcontainer/post-create.sh",
+  "postStartCommand": "./.devcontainer/post-start.sh"
 }
diff --git a/.devcontainer/docker-compose.yml b/.devcontainer/docker-compose.yml
index 1a2d269..eee9924 100644
--- a/.devcontainer/docker-compose.yml
+++ b/.devcontainer/docker-compose.yml
@@ -1,12 +1,8 @@
 services:
   app:
-    image: mcr.microsoft.com/devcontainers/base:debian-13
+    build:
+      context: ..
+      dockerfile: .devcontainer/Dockerfile
     command: sleep infinity
     volumes:
       - ..:/workspaces/repro
-      - npm-cache:/home/vscode/.cache/npm
-      - pip-cache:/home/vscode/.cache/pip
-
-volumes:
-  npm-cache:
-  pip-cache:
diff --git a/.devcontainer/on-create.sh b/.devcontainer/on-create.sh
index c74a536..b965956 100755
--- a/.devcontainer/on-create.sh
+++ b/.devcontainer/on-create.sh
@@ -1,44 +1,44 @@
 #!/usr/bin/env bash
 set -euxo pipefail
 
-mkdir -p "$HOME/.cache/npm" "$HOME/.cache/pip"
-sudo chown "$(id -u):$(id -g)" "$HOME/.cache" "$HOME/.cache/npm" "$HOME/.cache/pip" || true
+# The padawan-fw runc shim bind-mounts a mode-0700 tmpdir over /etc/ssl/certs when this
+# container was started. Repair the permissions so non-root users can traverse the
+# directory and use TLS normally for the lifetime of this container.
+sudo chmod 755 /etc/ssl/certs
 
-echo "=== user ==="
+echo "=== [onCreateCommand] user ==="
 whoami
 id
 
-echo "=== env ==="
-env | sort
-echo "=== filtered env ==="
-env | grep -E 'SSL|REQUESTS|CURL|NODE|NPM|PIP|PYTHON' || true
+echo "=== [onCreateCommand] python version (root) ==="
+sudo python3 --version
 
-echo "=== ssl bundle ==="
-ls -l /etc/ssl/certs || true
-ls -l /etc/ssl/certs/ca-certificates.crt || true
+echo "=== [onCreateCommand] python version (vscode) ==="
+python3 --version
+
+echo "=== [onCreateCommand] node version (root) ==="
+sudo "$(which node)" --version
 
-echo "=== python ssl defaults ==="
-python3 - <<'PY'
-import ssl
-print(ssl.get_default_verify_paths())
-PY
+echo "=== [onCreateCommand] node version (vscode) ==="
+node --version
+
+echo "=== [onCreateCommand] ssl bundle ==="
+ls -l /etc/ssl/certs/ca-certificates.crt || true
 
-echo "=== root curl ==="
+echo "=== [onCreateCommand] root curl ==="
 sudo bash -lc '
   set -euxo pipefail
-  whoami
-  id
-  env | grep -E "SSL|REQUESTS|CURL|NODE|NPM|PIP|PYTHON" || true
-  curl -Ivs https://github.com >/tmp/root-curl.txt 2>&1 || {
-    cat /tmp/root-curl.txt
+  echo "root curl user: $(whoami)"
+  curl -Ivs https://github.com >/tmp/oncreate-root-curl.txt 2>&1 || {
+    cat /tmp/oncreate-root-curl.txt
     exit 1
   }
-  cat /tmp/root-curl.txt
+  cat /tmp/oncreate-root-curl.txt
 '
 
-echo "=== user curl ==="
-curl -Ivs https://github.com >/tmp/user-curl.txt 2>&1 || {
-  cat /tmp/user-curl.txt
+echo "=== [onCreateCommand] user curl ==="
+curl -Ivs https://github.com >/tmp/oncreate-user-curl.txt 2>&1 || {
+  cat /tmp/oncreate-user-curl.txt
   exit 1
 }
-cat /tmp/user-curl.txt
+cat /tmp/oncreate-user-curl.txt
diff --git a/.devcontainer/post-create.sh b/.devcontainer/post-create.sh
new file mode 100755
index 0000000..5b221a2
--- /dev/null
+++ b/.devcontainer/post-create.sh
@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+set -euxo pipefail
+
+# The padawan-fw runc shim bind-mounts a mode-0700 tmpdir over /etc/ssl/certs when this
+# container was started. Repair the permissions so non-root users can traverse the
+# directory and use TLS normally for the lifetime of this container.
+sudo chmod 755 /etc/ssl/certs
+
+echo "=== [postCreateCommand] user ==="
+whoami
+id
+
+echo "=== [postCreateCommand] python version (root) ==="
+sudo python3 --version
+
+echo "=== [postCreateCommand] python version (vscode) ==="
+python3 --version
+
+echo "=== [postCreateCommand] node version (root) ==="
+sudo "$(which node)" --version
+
+echo "=== [postCreateCommand] node version (vscode) ==="
+node --version
+
+echo "=== [postCreateCommand] ssl bundle ==="
+ls -l /etc/ssl/certs/ca-certificates.crt || true
+
+echo "=== [postCreateCommand] root curl ==="
+sudo bash -lc '
+  set -euxo pipefail
+  echo "root curl user: $(whoami)"
+  curl -Ivs https://github.com >/tmp/postcreate-root-curl.txt 2>&1 || {
+    cat /tmp/postcreate-root-curl.txt
+    exit 1
+  }
+  cat /tmp/postcreate-root-curl.txt
+'
+
+echo "=== [postCreateCommand] user curl ==="
+curl -Ivs https://github.com >/tmp/postcreate-user-curl.txt 2>&1 || {
+  cat /tmp/postcreate-user-curl.txt
+  exit 1
+}
+cat /tmp/postcreate-user-curl.txt
+
+echo "=== [postCreateCommand] pip install (non-root) ==="
+pip install --user cowsay
+
+echo "=== [postCreateCommand] npm install (non-root) ==="
+mkdir -p /tmp/npm-test
+cd /tmp/npm-test
+npm install cowsay
diff --git a/.devcontainer/post-start.sh b/.devcontainer/post-start.sh
new file mode 100755
index 0000000..5fe07c4
--- /dev/null
+++ b/.devcontainer/post-start.sh
@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+set -euxo pipefail
+
+# The padawan-fw runc shim bind-mounts a mode-0700 tmpdir over /etc/ssl/certs each time
+# this container starts. Repair the permissions so non-root users can traverse the
+# directory and use TLS normally for the lifetime of this container session.
+sudo chmod 755 /etc/ssl/certs
+
+echo "=== [postStartCommand] user ==="
+whoami
+id
+
+echo "=== [postStartCommand] python version (root) ==="
+sudo python3 --version
+
+echo "=== [postStartCommand] python version (vscode) ==="
+python3 --version
+
+echo "=== [postStartCommand] node version (root) ==="
+sudo "$(which node)" --version
+
+echo "=== [postStartCommand] node version (vscode) ==="
+node --version
+
+echo "=== [postStartCommand] ssl bundle ==="
+ls -l /etc/ssl/certs/ca-certificates.crt || true
+
+echo "=== [postStartCommand] root curl ==="
+sudo bash -lc '
+  set -euxo pipefail
+  echo "root curl user: $(whoami)"
+  curl -Ivs https://github.com >/tmp/poststart-root-curl.txt 2>&1 || {
+    cat /tmp/poststart-root-curl.txt
+    exit 1
+  }
+  cat /tmp/poststart-root-curl.txt
+'
+
+echo "=== [postStartCommand] user curl ==="
+curl -Ivs https://github.com >/tmp/poststart-user-curl.txt 2>&1 || {
+  cat /tmp/poststart-user-curl.txt
+  exit 1
+}
+cat /tmp/poststart-user-curl.txt
diff --git a/.devcontainer/update-content.sh b/.devcontainer/update-content.sh
index b3676bb..00754a2 100755
--- a/.devcontainer/update-content.sh
+++ b/.devcontainer/update-content.sh
@@ -1,27 +1,44 @@
 #!/usr/bin/env bash
 set -euxo pipefail
 
-echo "=== updateContent user ==="
+# The padawan-fw runc shim bind-mounts a mode-0700 tmpdir over /etc/ssl/certs when this
+# container was started. Repair the permissions so non-root users can traverse the
+# directory and use TLS normally for the lifetime of this container.
+sudo chmod 755 /etc/ssl/certs
+
+echo "=== [updateContentCommand] user ==="
 whoami
 id
 
-echo "=== filtered env ==="
-env | grep -E 'SSL|REQUESTS|CURL|NODE|NPM|PIP|PYTHON' || true
+echo "=== [updateContentCommand] python version (root) ==="
+sudo python3 --version
 
-echo "=== tool versions ==="
-node --version
-npm --version
+echo "=== [updateContentCommand] python version (vscode) ==="
 python3 --version
-python3 -m pip --version
 
-echo "=== npm https test ==="
-npm view lodash version
+echo "=== [updateContentCommand] node version (root) ==="
+sudo "$(which node)" --version
+
+echo "=== [updateContentCommand] node version (vscode) ==="
+node --version
+
+echo "=== [updateContentCommand] ssl bundle ==="
+ls -l /etc/ssl/certs/ca-certificates.crt || true
 
-echo "=== pip https test ==="
-python3 -m pip install --user requests
+echo "=== [updateContentCommand] root curl ==="
+sudo bash -lc '
+  set -euxo pipefail
+  echo "root curl user: $(whoami)"
+  curl -Ivs https://github.com >/tmp/updatecontent-root-curl.txt 2>&1 || {
+    cat /tmp/updatecontent-root-curl.txt
+    exit 1
+  }
+  cat /tmp/updatecontent-root-curl.txt
+'
 
-echo "=== python ssl defaults ==="
-python3 - <<'PY'
-import ssl
-print(ssl.get_default_verify_paths())
-PY
+echo "=== [updateContentCommand] user curl ==="
+curl -Ivs https://github.com >/tmp/updatecontent-user-curl.txt 2>&1 || {
+  cat /tmp/updatecontent-user-curl.txt
+  exit 1
+}
+cat /tmp/updatecontent-user-curl.txt
diff --git a/README.md b/README.md
index b7cf87b..77381b4 100644
--- a/README.md
+++ b/README.md
@@ -1,67 +1,188 @@
 # Copilot cloud agent devcontainer non-root SSL repro
 
-This repository is a minimal reproduction for a suspected issue in the GitHub Copilot cloud agent when using a devcontainer.
+Minimal reproduction for the padawan-fw runc shim SSL bug in the GitHub Copilot cloud
+agent, and an active workbench for testing the devcontainer setup.
 
-## Summary
+---
 
-The goal is to test whether HTTPS/network operations behave differently for:
+## Root cause
 
-- root/setup-time commands, versus
-- the non-root devcontainer user (`vscode`)
+The Copilot cloud agent environment runs **`padawan-fw`**, a network firewall that
+performs TLS interception (MITM) on all outbound HTTPS. It installs a Bash shim at
+`/usr/bin/runc` that intercepts every `runc create` call and injects bind-mounts into
+the container's OCI `config.json` before the real `runc` runs.
 
-inside the Copilot cloud agent environment.
+The relevant part of the shim:
 
-This repo intentionally avoids:
+```bash
+CERT_TMP_DIR=$(mktemp -d)                           # drwx------ (mode 0700)
+cp "$CERT_PATH" "$CERT_TMP_DIR/ca-certificates.crt"
+chmod 644 "$CERT_TMP_DIR/ca-certificates.crt"       # fixes the FILE, not the DIR
+# missing: chmod 755 "$CERT_TMP_DIR"
+```
 
-- application code
-- private registries
-- custom CA certificates
-- custom SSL configuration
-- database setup
+Inside every container the result is:
 
-## What this repo does
+```
+drwx------ 2 root root  /etc/ssl/certs          ← 0700
+-rw-r--r-- 1 root root  /etc/ssl/certs/ca-certificates.crt  ← 0644
+```
 
-The devcontainer:
+`root` can traverse the 0700 dir (via `CAP_DAC_OVERRIDE`). Non-root users cannot, so
+`curl` as `vscode` fails immediately with exit 77 (`CURLE_SSL_CACERT_BADFILE`).
 
-- uses `mcr.microsoft.com/devcontainers/base:debian-13`
-- installs standard Node and Python devcontainer features
-- runs an `onCreateCommand` that:
-  - prints user and environment information
-  - checks the system CA bundle
-  - performs an HTTPS `curl` test as `root`
-  - performs the same HTTPS `curl` test as the non-root user
-- runs an `updateContentCommand` that:
-  - prints tool versions
-  - performs HTTPS-backed package-manager operations as the non-root user:
-    - `npm view lodash version`
-    - `python3 -m pip install --user requests`
+The shim runs at the OCI layer and affects every container regardless of the base image.
 
-## Expected result
+**Real fix:** add `chmod 755 "$CERT_TMP_DIR"` to the padawan-fw shim right after
+`mktemp -d`.
 
-All HTTPS operations should succeed:
+---
 
-- root `curl`
-- user `curl`
-- `npm view lodash version`
-- `python3 -m pip install --user requests`
+## Current devcontainer approach
 
-## Actual result in Copilot cloud agent
+### Base image
 
-If the suspected issue is present, one or more non-root operations fail with SSL/certificate/network errors, while root operations succeed.
+`mcr.microsoft.com/devcontainers/base:trixie` (Debian 13 / Trixie).
 
-## Local comparison
+Chosen because:
+- Debian is the standard base for devcontainers
+- Trixie ships Python 3.13 in its default repos (convenient for the test, though we
+  install via pyenv anyway for version-pinning reasons — see below)
 
-This repo is also intended to be run locally in a normal Dev Containers environment.
+### Python and Node: version-pinnable, not system-level
 
-If it works locally but fails in Copilot cloud agent, that suggests a cloud-agent/platform issue rather than a repo-specific configuration problem.
+Devcontainer `features` were dropped in favour of tools installed directly in the
+Dockerfile, giving full control over TLS calls during the build:
 
-## Files
+| Tool | Installed via | Location | Version pin |
+|------|--------------|----------|-------------|
+| Python | **pyenv** (compiled from source) | `/usr/local/pyenv` | `ARG PYTHON_VERSION=3.13` |
+| Node | **nvm** | `/usr/local/nvm` | `ARG NODE_VERSION=lts` |
 
-- `.devcontainer/devcontainer.json`
-- `.devcontainer/docker-compose.yml`
-- `.devcontainer/on-create.sh`
-- `.devcontainer/update-content.sh`
+Both are installed as root to world-readable system-wide paths. Symlinks in
+`/usr/local/bin/` make `python3`, `pip`, `pip3`, `node`, `npm`, `npx` available to
+all users and `sudo`.
 
-## Notes
+To pin a different version, rebuild with a build-arg:
 
-This reproduction does not use any custom CA certificates or certificate overrides.
+```bash
+docker build --build-arg PYTHON_VERSION=3.12 --build-arg NODE_VERSION=20 \
+  -f .devcontainer/Dockerfile .
+```
+
+### SSL workaround: `chmod 755 /etc/ssl/certs`
+
+Moving to a local Dockerfile means all Dockerfile `RUN` steps execute as root and can
+traverse the 0700-mounted `/etc/ssl/certs` without any cert redirection. So the
+previous workaround machinery was dropped entirely:
+
+- ❌ removed: CA bundle copy to `/usr/local/share/ca-certificates.crt`
+- ❌ removed: `~/.curlrc` cacert overrides
+- ❌ removed: `git config --system http.sslCAInfo`
+- ❌ removed: `/etc/environment` and `/etc/profile.d/ca-bundle-workaround.sh`
+- ❌ removed: `ENV CURL_CA_BUNDLE / GIT_SSL_CAINFO / SSL_CERT_FILE / …` block
+- ❌ removed: `features` block in `devcontainer.json`
+
+Each Dockerfile `RUN` step that makes network calls opens with
+`chmod 755 /etc/ssl/certs` — harmless when the dir is already 755, essential when the
+shim has mounted a 0700 dir.
+
+Each lifecycle hook script opens with `sudo chmod 755 /etc/ssl/certs` for the same
+reason: the shim applies a fresh bind-mount every time a container starts, so
+`postStartCommand` in particular must re-apply the fix on every boot.
+
+---
+
+## Repository structure
+
+```
+.devcontainer/
+  Dockerfile            # trixie base + pyenv Python + nvm Node
+  devcontainer.json     # no features; references docker-compose.yml + hooks
+  docker-compose.yml    # builds Dockerfile; mounts workspace
+  on-create.sh          # onCreateCommand   — chmod fix + version/curl checks
+  update-content.sh     # updateContentCommand — chmod fix + version/curl checks
+  post-create.sh        # postCreateCommand — chmod fix + version/curl/pip/npm checks
+  post-start.sh         # postStartCommand  — chmod fix + version/curl checks
+```
+
+### What each hook script does
+
+1. `sudo chmod 755 /etc/ssl/certs` — shim workaround
+2. `whoami` / `id`
+3. Python and Node version checks (root and non-root)
+4. `ls -l /etc/ssl/certs/ca-certificates.crt`
+5. `curl -Ivs https://github.com` as root and as `vscode`
+6. (`post-create.sh` only) `pip install --user cowsay` and `npm install cowsay`
+
+---
+
+## Current status / what the next agent needs to do
+
+The Dockerfile was written but **the image build has not yet been completed or
+verified**. The build was started and then stopped because it requires outbound access
+to domains that may be firewall-blocked in the runner environment.
+
+### Domains that must be reachable during `docker build`
+
+| Step | Domain(s) needed |
+|------|-----------------|
+| `apt-get update` | `deb.debian.org`, `security.debian.org` |
+| pyenv git clone | `github.com` |
+| pyenv Python build | `www.python.org` (source tarball download) |
+| nvm install script | `raw.githubusercontent.com` |
+| nvm Node download | `nodejs.org` |
+
+### Steps to complete
+
+1. **Verify the domains above are reachable** from a `docker build` container. If any
+   are blocked, ask the user to lift the firewall restriction before proceeding.
+
+2. **Build the image:**
+   ```bash
+   cd /home/runner/work/devcontainer-ssl-problem/devcontainer-ssl-problem
+   docker build --no-cache -t repro-test -f .devcontainer/Dockerfile .
+   ```
+
+3. **Start a container and run the hook scripts manually** (simulating what the
+   devcontainer lifecycle would do):
+   ```bash
+   docker run -d --name repro-test-ctr repro-test sleep infinity
+   docker exec -u vscode repro-test-ctr bash /workspaces/repro/.devcontainer/on-create.sh
+   docker exec -u vscode repro-test-ctr bash /workspaces/repro/.devcontainer/update-content.sh
+   docker exec -u vscode repro-test-ctr bash /workspaces/repro/.devcontainer/post-create.sh
+   docker exec -u vscode repro-test-ctr bash /workspaces/repro/.devcontainer/post-start.sh
+   ```
+
+4. **Run manual version and install checks inside the running container:**
+   ```bash
+   docker exec repro-test-ctr python3 --version
+   docker exec repro-test-ctr pip3 --version
+   docker exec repro-test-ctr node --version
+   docker exec repro-test-ctr npm --version
+   docker exec -u vscode repro-test-ctr python3 --version
+   docker exec -u vscode repro-test-ctr node --version
+   docker exec -u vscode repro-test-ctr pip install --user cowsay
+   docker exec -u vscode repro-test-ctr bash -c 'cd /tmp && npm install cowsay'
+   ```
+
+5. **Summarise hook output and manual check results** and update the
+   [Test results](#test-results) section below.
+
+6. **Commit and push.**
+
+---
+
+## Test results
+
+> **Not yet recorded.** The image build has not been completed. See
+> [Current status](#current-status--what-the-next-agent-needs-to-do) above.
+
+### Expected results (after build succeeds)
+
+| Hook | User | curl | python3 --version | node --version |
+|------|------|------|-------------------|----------------|
+| `onCreateCommand` | vscode | ✅ HTTP 200 | ✅ 3.13.x | ✅ LTS |
+| `updateContentCommand` | vscode | ✅ HTTP 200 | ✅ 3.13.x | ✅ LTS |
+| `postCreateCommand` | vscode | ✅ HTTP 200 | ✅ 3.13.x | ✅ LTS |
+| `postStartCommand` | vscode | ✅ HTTP 200 | ✅ 3.13.x | ✅ LTS |