docs: add unit test audit extension design

docs/plans/2026-02-27-unit-test-audit-design.md

@@ -0,0 +1,63 @@
+# Unit Test Audit Extension Design
+
+## Goal
+
+Extend the PortTracker `audit` command to classify unit tests (not just features) by inspecting .NET test source code with Roslyn.
+
+## Architecture
+
+Parameterize the existing audit pipeline (`AuditCommand` + `SourceIndexer` + `FeatureClassifier`) to support both `features` and `unit_tests` tables. No new files — the same indexer and classifier logic applies to test methods.
+
+## CLI Interface
+
+```
+dotnet run -- audit --type features|tests|all [--source <path>] [--module <id>] [--execute]
+```
+
+| Flag | Default (features) | Default (tests) |
+|------|-------------------|-----------------|
+| `--type` | `features` | — |
+| `--source` | `dotnet/src/ZB.MOM.NatsNet.Server` | `dotnet/tests/ZB.MOM.NatsNet.Server.Tests` |
+| `--output` | `reports/audit-results.csv` | `reports/audit-results-tests.csv` |
+
+- `--type all` runs both sequentially.
+- `--source` override works for either type.
+
+## Changes Required
+
+### AuditCommand.cs
+
+1. Add `--type` option with values `features`, `tests`, `all`.
+2. Thread an `AuditTarget` (table name + default source + default output + display label) through `RunAudit` and `ApplyUpdates`.
+3. `--type all` calls `RunAudit` twice with different targets.
+4. `ApplyUpdates` uses the target's table name in UPDATE SQL.
+
+### FeatureClassifier.cs
+
+No changes. Same N/A lookup and classification logic applies to unit tests.
+
+### SourceIndexer.cs
+
+No changes. Already generic — just pass a different directory path.
+
+## Pre-audit DB Reset
+
+Before running the test audit, manually reset deferred tests to `unknown`:
+
+```sql
+sqlite3 porting.db "UPDATE unit_tests SET status = 'unknown' WHERE status = 'deferred';"
+```
+
+## Execution Sequence
+
+1. Reset deferred tests: `sqlite3 porting.db "UPDATE unit_tests SET status = 'unknown' WHERE status = 'deferred';"`
+2. Run audit: `dotnet run -- audit --type tests --db porting.db --execute`
+3. Verify results and generate report.
+
+## Classification Behavior for Tests
+
+Same priority as features:
+1. **N/A**: Go method matches logging/signal patterns → `n_a`
+2. **Method found**: Test class + method exists in test project → `verified` or `stub`
+3. **Class exists, method missing**: → `deferred` ("method not found")
+4. **Class not found**: → `deferred` ("class not found")