Document mc-proxy migration in PROGRESS.md

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

PROGRESS.md

@@ -99,6 +99,37 @@ Dependencies added:
 
 Result: vet clean, lint 0 issues, builds successfully.
 
+### Phase 11a: mc-proxy Migration (2026-03-25)
+
+mc-proxy migrated db and config to mcdsl. Different pattern from mcat
+because mc-proxy doesn't embed config.Base (no [server] or [mcias] sections).
+
+| Changed | How |
+|---------|-----|
+| `internal/db/db.go` Open | Delegates to `mcdsl/db.Open` |
+| `internal/db/migrations.go` | Function-based migrations → `mcdsl/db.Migration` SQL strings |
+| `internal/db/snapshot.go` | Delegates to `mcdsl/db.Snapshot` |
+| `internal/config/config.go` Duration | Type alias for `mcdsl/config.Duration` |
+| `internal/config/config.go` Load | Uses `mcdsl/config.Load[T]` + Validator interface |
+
+Key design decisions:
+- Store wrapper kept (has CRUD methods specific to mc-proxy)
+- `type Duration = mcdslconfig.Duration` alias so all existing code
+  referencing `config.Duration` continues to work unchanged
+- mc-proxy's complex validation stays as a Validate() method
+- Manual env overrides kept for int64 rate_limit (reflection can't handle)
+
+Dependencies removed as direct:
+- `modernc.org/sqlite` (now indirect via mcdsl)
+- `github.com/pelletier/go-toml/v2` (now indirect via mcdsl)
+
+Behavioral change: invalid duration env overrides are now silently ignored
+(test updated to match).
+
+Result: all tests pass, builds clean. Net -129 lines.
+
 ## Next Steps
 
-- Phase 11: Broader adoption (metacrypt, mcr, mc-proxy, mcias)
+- Phase 11b: mcr migration
+- Phase 11c: metacrypt migration
+- Phase 11d: mcias migration