Update TODO.md: standard structure and Workflow section (#44)

Reviewed-on: #44
Co-authored-by: sneak <sneak@sneak.berlin>
Co-committed-by: sneak <sneak@sneak.berlin>

TODO.md

@@ -1,65 +1,85 @@
-# Pixa 1.0 TODO
+# Workflow
 
-Remaining tasks sorted by priority for a working 1.0 release.
+* branch (from `main`)
+* do the work in Next Step
+* move Next Step to the top of Completed Steps
+* move the top item of Future Steps into Next Step
+* commit (`TODO.md` changes in the same commit as the work)
+* merge to `main` if the branch is not protected, otherwise open a PR
+* push
 
-## P0: Critical for 1.0
+# Status
 
-### Image Processing
-- [x] Add WebP encoding support (currently returns error)
-- [x] Add AVIF encoding support (implemented via govips)
+pre-1.0. No git tags exist. main (6b4a1d7, 2026-04-07) is current with
+origin; recent work extracted the internal/magic and internal/allowlist
+packages. The 10 gosec findings from the 2026-07-06 morning survey are
+NOT fixed on main: the newest gosec/lint fix commits are from
+2026-02-25 (85729d9, ce6db76) and nothing since touches gosec, so those
+findings remain open.
 
-### Manual Testing (verify auth/encrypted URLs work)
-- [ ] Manual test: visit `/`, see login form
-- [ ] Manual test: enter wrong key, see error
-- [ ] Manual test: enter correct signing key, see generator form
-- [ ] Manual test: generate encrypted URL, verify it works
-- [ ] Manual test: wait for expiration or use short TTL, verify expired URL returns 410
-- [ ] Manual test: logout, verify redirected to login
+# Next Step
 
-### Cache Management
-- [ ] Implement cache size management/eviction (prevent disk from filling up)
+Fix the 10 open gosec lint findings so make check passes on main again
+(main must always be green; no gosec fix commits have landed since
+2026-02-25). No blanket suppressions; fix or justify each finding
+individually.
 
-### Configuration
-- [ ] Validate configuration on startup (fail fast on bad config)
+# Completed Steps
 
-## P1: Important for Production
+- 2026-04-07 extract magic byte detection into internal/magic (#42)
+- 2026-03-25 extract allowlist package from internal/imgcache (#41)
+- 2026-03-25 move schema_migrations table creation into 000.sql (#36)
+- 2026-03-20 enforce and document exact-match-only signature
+  verification (#40)
+- 2026-03-20 bound imageprocessor.Process input read to prevent
+  unbounded memory use (#37); consolidate appname into an
+  internal/globals constant (#34)
+- 2026-03-18 parse version prefix from migration filenames (#33)
+- 2026-03-15 QA audit fixes for 1.0/MVP readiness (#25)
+- 2026-03-02 split Dockerfile with pre-built golangci-lint stage for
+  faster CI (#23)
+- 2026-02-25 repo policy compliance: CI workflow, hash-pinned images,
+  golangci-lint and gosec fixes of that date (#14); arm64 Docker build
+  fix (#16)
+- 2026-01-08 WebP and AVIF encoding support via govips (both former P0
+  image processing items, now done)
 
-### Security
-- [ ] Implement blocked networks configuration (extend SSRF protection)
-- [ ] Add rate limiting global concurrent fetches (prevent resource exhaustion)
+# Future Steps
 
-### Image Processing
-- [ ] Implement EXIF/metadata stripping (privacy)
-
-## P2: Nice to Have
-
-### Security
-- [ ] Implement referer blacklist
-- [ ] Add rate limiting per-IP
-- [ ] Add rate limiting per-origin
-
-### HTTP Response Handling
-- [ ] Implement Last-Modified headers
-- [ ] Implement Vary header for content negotiation
-- [ ] Implement X-Request-ID propagation
-
-### Additional Endpoints
-- [ ] Implement auto-format selection (format=auto based on Accept header)
-
-### Configuration
-- [ ] Add all configuration options from README
-- [ ] Implement environment variable overrides
-- [ ] Implement YAML config file support
-
-### Operational
-- [ ] Implement Sentry error reporting (optional)
-- [ ] Add comprehensive request logging
-- [ ] Add performance metrics (Prometheus)
-- [ ] Write integration tests for image proxy flow
-- [ ] Write load tests to verify 1-5k req/s target
-
-### Documentation
-- [ ] Document configuration options
-- [ ] Document API endpoints
-- [ ] Document deployment guide
-- [ ] Add example nginx/caddy reverse proxy config
+- P0: manual test pass of the auth and encrypted URL flows, then
+  commit the checked-off results to TODO.md: visit / and see the login
+  form; wrong key shows an error; correct signing key shows the
+  generator form; a generated encrypted URL serves the image; an
+  expired URL (short TTL) returns 410; logout redirects back to login
+- P0: implement cache size management and eviction so the disk cannot
+  fill up
+- P0: validate configuration on startup, fail fast on bad config
+- P1: implement blocked networks configuration to extend SSRF
+  protection
+- P1: rate limit global concurrent upstream fetches to prevent
+  resource exhaustion
+- P1: strip EXIF and other metadata from processed images (privacy)
+- P2: security
+    - referer blacklist
+    - per-IP rate limiting
+    - per-origin rate limiting
+- P2: HTTP response handling
+    - Last-Modified headers
+    - Vary header for content negotiation
+    - X-Request-ID propagation
+- P2: auto format selection (format=auto based on Accept header)
+- P2: configuration
+    - add all configuration options from README
+    - environment variable overrides
+    - YAML config file support
+- P2: operational
+    - optional Sentry error reporting
+    - comprehensive request logging
+    - Prometheus performance metrics
+    - integration tests for the image proxy flow
+    - load tests to verify the 1k to 5k req/s target
+- P2: documentation
+    - configuration options
+    - API endpoints
+    - deployment guide
+    - example nginx or caddy reverse proxy config