feat(templates): scaffold a .gitignore that excludes .env and .venv

[michaelxu2288]

What

agentex init writes .env.example and tells users to create .env with an API key. .dockerignore protects the image build, but no template ships a .gitignore, so git init && git add . in a scaffolded folder commits .env (and .venv). Adds a .gitignore.j2 to all 19 templates (secrets, Python artifacts, tool caches; .env.example stays committable), registers it in root_templates in commands/init.py, and adds a parametrized test asserting every scaffold renders it with .env and .venv/ excluded.

Test

tests/lib/cli/test_init_templates.py: 45 passed (26 existing + 19 new). ruff clean.

https://claude.ai/code/session_01HCVKnA7LeJZ44nxZz1uzF3

Confidence Score: 4/5

The PR is not yet safe to merge because rerunning initialization can make .env.example ignored in existing projects with a common preexisting negation.

Findings

1.  Gitignore Rule Order Breaks ▶

Fix with agent prompt

### Issue 1
src/agentex/lib/cli/commands/init.py:127-129
When an existing `.gitignore` already contains `!.env.example` but does not contain `.env.*`, this order-insensitive check skips the existing negation and appends `.env.*` after it. Git uses the last matching rule, so rerunning `agentex init` then ignores `.env.example` even though the scaffold promises that the example file remains committable. Preserve the template rules as an ordered block or otherwise account for their effective order when merging.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Summary

• Adds common exclusions for environment files, virtual environments, Python artifacts, and tool caches.
• Keeps .env.example committable in newly generated projects.
• Adds coverage across all template types and for preserving an existing .gitignore.
• The new merge implementation does not preserve ordering semantics between existing and appended rules.

_{Reviews (2) · Last reviewed commit: "fix(init): merge scaffold entries into a..."}

[greptile-apps]

Gitignore Rule Order Breaks

When an existing .gitignore already contains !.env.example but does not contain .env.*, this order-insensitive check skips the existing negation and appends .env.* after it. Git uses the last matching rule, so rerunning agentex init then ignores .env.example even though the scaffold promises that the example file remains committable. Preserve the template rules as an ordered block or otherwise account for their effective order when merging.

Prompt To Fix With AI

This is a comment left during a code review.
Path: src/agentex/lib/cli/commands/init.py
Line: 127-129

Comment:
**Gitignore Rule Order Breaks**

When an existing `.gitignore` already contains `!.env.example` but does not contain `.env.*`, this order-insensitive check skips the existing negation and appends `.env.*` after it. Git uses the last matching rule, so rerunning `agentex init` then ignores `.env.example` even though the scaffold promises that the example file remains committable. Preserve the template rules as an ordered block or otherwise account for their effective order when merging.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.