chore(code): add worktree config for posthog code

[adboio]

Problem

this PR adds support for .worktreeinclude and .worktreelink in posthog code: PostHog/code#1344

and we want posthog worktrees to be easy in posthog code :)

Changes

• adds .worktreeinclude, .worktreelink, and posthog code env setup script to the posthog main repo
• adds a cache layer to the flox claude setup hook

How did you test this code?

manual testing

worktrees are working smoothly in posthog code with the posthog main repo now

👉 Stay up-to-date with PostHog coding conventions for a smoother review.

Publish to changelog?

Docs update

[adboio]

• chore(code): add worktree config for posthog code #52566 👈 (View in Graphite)
• master

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[greptile-apps]

Important Files Changed

Filename	Overview
.claude/hooks/setup-flox.sh	Added a cache layer for the flox env snapshot; cache never auto-invalidates when flox.toml changes, and mkdir -p ordering is slightly off.
.worktreeinclude	New file listing .env, .env.local, .envrc to be copied into each worktree — correct and minimal.
.worktreelink	New file symlinking .flox into each worktree so the shared flox environment is available everywhere.
.posthog-code/environments/posthog.toml	New posthog-code environment definition with direnv allow . as the setup script.
.posthog-code/.gitignore	Ignores worktrees/ and worktrees-dev/ directories generated by the worktree tool.

Prompt To Fix All With AI

This is a comment left during a code review.
Path: .claude/hooks/setup-flox.sh
Line: 22-26

Comment:
**Cache never auto-invalidates on flox environment changes**

The fast path loads the cache unconditionally. If someone updates `flox.toml` (adds/removes packages, changes `[vars]`) and restarts a Claude session, Claude will silently continue using the stale environment — new tools won't be on `PATH`, removed vars will persist, etc. The comment documents manual invalidation, but this is easy to miss in practice.

Consider checksumming the flox manifest to auto-invalidate:

```bash
# Fast path: reuse cached env if flox manifest hasn't changed
FLOX_MANIFEST="$PROJECT_DIR/.flox/env/manifest.toml"
MANIFEST_HASH=""
if command -v md5sum &>/dev/null; then
  MANIFEST_HASH=$(md5sum "$FLOX_MANIFEST" 2>/dev/null | awk '{print $1}')
elif command -v md5 &>/dev/null; then
  MANIFEST_HASH=$(md5 -q "$FLOX_MANIFEST" 2>/dev/null)
fi

if [ -f "$CACHE_FILE" ]; then
  CACHED_HASH=$(head -1 "$CACHE_FILE" | sed 's/^# manifest-hash: //')
  if [ -n "$MANIFEST_HASH" ] && [ "$CACHED_HASH" = "$MANIFEST_HASH" ]; then
    tail -n +2 "$CACHE_FILE" >> "$CLAUDE_ENV_FILE"
    exit 0
  fi
fi
```

And then prefix the cache file with `# manifest-hash: $MANIFEST_HASH` on write. Even if `md5sum`/`md5` isn't available, falling through to the slow path is safe.

How can I resolve this? If you propose a fix, please make it concise.

---

This is a comment left during a code review.
Path: .claude/hooks/setup-flox.sh
Line: 46-48

Comment:
**`mkdir -p` called after writing to env file, before writing cache**

The `mkdir -p "$(dirname "$CACHE_FILE")"` is called after `$CLAUDE_ENV_FILE` is written but before the cache file is written. If `.flox/cache/` doesn't exist for some reason (e.g., fresh flox setup without the venv yet), `printf '%s' "$ENV_CONTENT" > "$CACHE_FILE"` will fail silently, and the next session will skip directly to the slow path again (because no cache file exists). This won't cause incorrect behavior, but it means the caching optimization will never take effect in that edge case.

Moving `mkdir -p` before the `$CLAUDE_ENV_FILE` write would be more defensive:

```suggestion
mkdir -p "$(dirname "$CACHE_FILE")"
printf '%s' "$ENV_CONTENT" >> "$CLAUDE_ENV_FILE"
printf '%s' "$ENV_CONTENT" > "$CACHE_FILE"
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "chore(code): add worktree config for pos..." | Re-trigger Greptile}

[greptile-apps]

Cache never auto-invalidates on flox environment changes

The fast path loads the cache unconditionally. If someone updates flox.toml (adds/removes packages, changes [vars]) and restarts a Claude session, Claude will silently continue using the stale environment — new tools won't be on PATH, removed vars will persist, etc. The comment documents manual invalidation, but this is easy to miss in practice.

Consider checksumming the flox manifest to auto-invalidate:

# Fast path: reuse cached env if flox manifest hasn't changed
FLOX_MANIFEST="$PROJECT_DIR/.flox/env/manifest.toml"
MANIFEST_HASH=""
if command -v md5sum &>/dev/null; then
  MANIFEST_HASH=$(md5sum "$FLOX_MANIFEST" 2>/dev/null | awk '{print $1}')
elif command -v md5 &>/dev/null; then
  MANIFEST_HASH=$(md5 -q "$FLOX_MANIFEST" 2>/dev/null)
fi

if [ -f "$CACHE_FILE" ]; then
  CACHED_HASH=$(head -1 "$CACHE_FILE" | sed 's/^# manifest-hash: //')
  if [ -n "$MANIFEST_HASH" ] && [ "$CACHED_HASH" = "$MANIFEST_HASH" ]; then
    tail -n +2 "$CACHE_FILE" >> "$CLAUDE_ENV_FILE"
    exit 0
  fi
fi

And then prefix the cache file with # manifest-hash: $MANIFEST_HASH on write. Even if md5sum/md5 isn't available, falling through to the slow path is safe.

Prompt To Fix With AI

This is a comment left during a code review.
Path: .claude/hooks/setup-flox.sh
Line: 22-26

Comment:
**Cache never auto-invalidates on flox environment changes**

The fast path loads the cache unconditionally. If someone updates `flox.toml` (adds/removes packages, changes `[vars]`) and restarts a Claude session, Claude will silently continue using the stale environment — new tools won't be on `PATH`, removed vars will persist, etc. The comment documents manual invalidation, but this is easy to miss in practice.

Consider checksumming the flox manifest to auto-invalidate:

```bash
# Fast path: reuse cached env if flox manifest hasn't changed
FLOX_MANIFEST="$PROJECT_DIR/.flox/env/manifest.toml"
MANIFEST_HASH=""
if command -v md5sum &>/dev/null; then
  MANIFEST_HASH=$(md5sum "$FLOX_MANIFEST" 2>/dev/null | awk '{print $1}')
elif command -v md5 &>/dev/null; then
  MANIFEST_HASH=$(md5 -q "$FLOX_MANIFEST" 2>/dev/null)
fi

if [ -f "$CACHE_FILE" ]; then
  CACHED_HASH=$(head -1 "$CACHE_FILE" | sed 's/^# manifest-hash: //')
  if [ -n "$MANIFEST_HASH" ] && [ "$CACHED_HASH" = "$MANIFEST_HASH" ]; then
    tail -n +2 "$CACHE_FILE" >> "$CLAUDE_ENV_FILE"
    exit 0
  fi
fi
```

And then prefix the cache file with `# manifest-hash: $MANIFEST_HASH` on write. Even if `md5sum`/`md5` isn't available, falling through to the slow path is safe.

How can I resolve this? If you propose a fix, please make it concise.

[gantoine]

auto invalidating would be nice if its not too much overhead

[adboio]

added!

[gantoine]

nice!