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website-enchun-mgr/.agent/skills/turborepo/references/caching/gotchas.md
pkupuk ad8e2e313e chore(agent): configure AI agents and tools
Add configuration for BMad, Claude, OpenCode, and other AI agent tools and workflows.
2026-02-11 11:51:23 +08:00

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# Debugging Cache Issues
## Diagnostic Tools
### `--summarize`
Generates a JSON file with all hash inputs. Compare two runs to find differences.
```bash
turbo build --summarize
# Creates .turbo/runs/<run-id>.json
```
The summary includes:
- Global hash and its inputs
- Per-task hashes and their inputs
- Environment variables that affected the hash
**Comparing runs:**
```bash
# Run twice, compare the summaries
diff .turbo/runs/<first-run>.json .turbo/runs/<second-run>.json
```
### `--dry` / `--dry=json`
See what would run without executing anything:
```bash
turbo build --dry
turbo build --dry=json # machine-readable output
```
Shows cache status for each task without running them.
### `--force`
Skip reading cache, re-execute all tasks:
```bash
turbo build --force
```
Useful to verify tasks actually work (not just cached results).
## Unexpected Cache Misses
**Symptom:** Task runs when you expected a cache hit.
### Environment Variable Changed
Check if an env var in the `env` key changed:
```json
{
"tasks": {
"build": {
"env": ["API_URL", "NODE_ENV"]
}
}
}
```
Different `API_URL` between runs = cache miss.
### .env File Changed
`.env` files aren't tracked by default. Add to `inputs`:
```json
{
"tasks": {
"build": {
"inputs": ["$TURBO_DEFAULT$", ".env", ".env.local"]
}
}
}
```
Or use `globalDependencies` for repo-wide env files:
```json
{
"globalDependencies": [".env"]
}
```
### Lockfile Changed
Installing/updating packages changes the global hash.
### Source Files Changed
Any file in the package (or in `inputs`) triggers a miss.
### turbo.json Changed
Config changes invalidate the global hash.
## Incorrect Cache Hits
**Symptom:** Cached output is stale/wrong.
### Missing Environment Variable
Task uses an env var not listed in `env`:
```javascript
// build.js
const apiUrl = process.env.API_URL; // not tracked!
```
Fix: add to task config:
```json
{
"tasks": {
"build": {
"env": ["API_URL"]
}
}
}
```
### Missing File in Inputs
Task reads a file outside default inputs:
```json
{
"tasks": {
"build": {
"inputs": [
"$TURBO_DEFAULT$",
"../../shared-config.json" // file outside package
]
}
}
}
```
## Useful Flags
```bash
# Only show output for cache misses
turbo build --output-logs=new-only
# Show output for everything (debugging)
turbo build --output-logs=full
# See why tasks are running
turbo build --verbosity=2
```
## Quick Checklist
Cache miss when expected hit:
1. Run with `--summarize`, compare with previous run
2. Check env vars with `--dry=json`
3. Look for lockfile/config changes in git
Cache hit when expected miss:
1. Verify env var is in `env` array
2. Verify file is in `inputs` array
3. Check if file is outside package directory