## Implementation Plan

**Root cause identified**: Double compression – nginx (`gzip on`, `gzip_proxied any`) re-compresses the already-compressed response from Python’s `GZipMiddleware`, leading to metadata corruption and the reported Content-Length mismatch.

**Fix**: Remove `GZipMiddleware` from the Python application. nginx (which is always deployed in production) already handles compression correctly for all proxy responses. This eliminates the double-compression anti-pattern without losing compression at the edge.

### Changes to make

1. **`/workspace/repo/main.py`** (line approximately 614)  
   Remove the middleware registration line:

   ```python
   app.add_middleware(GZipMiddleware, minimum_size=1000)
   ```

2. **`/workspace/repo/main.py`** (top of file)  
   Remove the corresponding import:

   ```python
   from starlette.middleware.gzip import GZipMiddleware
   ```

   If this import is used elsewhere (unlikely), leave it; otherwise delete it.

3. **No other files need modification**.  
   - nginx configuration (`nginx/nginx.conf.template`) remains unchanged – `gzip on` already covers all response types.  
   - Tests do not cover Content-Length or GZip behaviour, and removal will not break any existing test.

### Verifying correctness

- The application will serve uncompressed responses in development (no nginx). This is acceptable and standard behaviour.  
- In production, nginx adds compression correctly without double-compressing.  
- The test suite must pass, and no new lint violations may be introduced.

### Execution steps

1. Open `main.py`.  
2. Comment or remove the `from starlette.middleware.gzip import GZipMiddleware` line.  
3. Comment or remove the `app.add_middleware(GZipMiddleware, minimum_size=1000)` line.  
4. Run `pip install -e '.[dev]' -q` to ensure dependencies are installed.  
5. Run `python -m pytest` to confirm all tests pass.  
6. Run the project’s linter (e.g., `ruff check .` or equivalent) to confirm no new violations.  

---

## Definition of Done

- [ ] `GZipMiddleware` import and middleware registration are removed from `main.py`.  
- [ ] The project’s test command completes with zero failures:  
      `pip install -e '.[dev]' -q && python -m pytest`  
- [ ] No new lint violations are introduced (lint command passes cleanly).  
- [ ] The server no longer sends `Content-Encoding: gzip` when running without nginx; production nginx continues to compress responses correctly.