refactor(devcontainer): always render postCreate.sh

Previously postCreate.sh only existed when add_claude=yes; the
add_claude=no case used a long inline bash string in
postCreateCommand. Tidier to always have a script and gate the
Claude-specific bits with Jinja {% if add_claude %} inside it, per
PR #337 review.

The meta repo now has its own .devcontainer/postCreate.sh that
mirrors the add_claude=no rendering, and its devcontainer.json
calls it the same way. Drift test still passes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: gilesknap

.devcontainer/devcontainer.json

@@ -69,6 +69,5 @@
     ],
     // Mount the parent as /workspaces so we can pip install peers as editable
     "workspaceMount": "source=${localWorkspaceFolder}/..,target=/workspaces,type=bind",
-    // After the container is created, recreate the venv then make pre-commit first run faster
-    "postCreateCommand": "uv venv --clear && uv sync && pre-commit install --install-hooks"
+    "postCreateCommand": ".devcontainer/postCreate.sh"
 }

.devcontainer/postCreate.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+set -euo pipefail
+
+# Install Python dependencies and pre-commit hooks
+uv venv --clear
+uv sync
+pre-commit install --install-hooks
+
+# Initialise git submodules if any are declared
+[ -f .gitmodules ] && git submodule update --init || true

template/.devcontainer/devcontainer.json.jinja

@@ -100,13 +100,11 @@
         }{% endif %}
     ],
     // Mount the parent as /workspaces so we can pip install peers as editable
-    "workspaceMount": "source=${localWorkspaceFolder}/..,target=/workspaces,type=bind",{% if add_claude %}
-    "postCreateCommand": ".devcontainer/postCreate.sh",
+    "workspaceMount": "source=${localWorkspaceFolder}/..,target=/workspaces,type=bind",
+    "postCreateCommand": ".devcontainer/postCreate.sh"{% if add_claude %},
     "postStartCommand": ".devcontainer/postStart.sh",
     // VS Code's Dev Containers extension re-injects its credential bridge
     // when the editor attaches — after postStart has already run. Re-run
     // the cleanup at attach so the leak is closed before any git operation.
-    "postAttachCommand": ".devcontainer/postStart.sh"{% else %}
-    // After the container is created, recreate the venv then make pre-commit first run faster
-    "postCreateCommand": "uv venv --clear && uv sync && pre-commit install --install-hooks"{% endif %}
+    "postAttachCommand": ".devcontainer/postStart.sh"{% endif %}
 }

…_claude %}postCreate.sh{% endif %}.jinja …mplate/.devcontainer/postCreate.sh.jinjatemplate/.devcontainer/{% if add_claude %}postCreate.sh{% endif %}.jinja renamed to template/.devcontainer/postCreate.sh.jinja template/.devcontainer/{% if add_claude %}postCreate.sh{% endif %}.jinja renamed to template/.devcontainer/postCreate.sh.jinja

@@ -1,9 +1,9 @@
 #!/bin/bash
 set -euo pipefail
-
+{% if add_claude %}
 # Install Claude Code CLI
 curl -fsSL https://claude.ai/install.sh | bash
-
+{% endif %}
 # Install Python dependencies and pre-commit hooks
 uv venv --clear
 uv sync