feat(marketplace): command consolidation + 8 new plugins (v8.1.0 → v9.0.0) [BREAKING]

Phase 1b: Rename all ~94 commands across 12 plugins to /<noun> <action>
sub-command pattern. Git-flow consolidated from 8→5 commands (commit
variants absorbed into --push/--merge/--sync flags). Dispatch files,
name: frontmatter, and cross-reference updates for all plugins.

Phase 2: Design documents for 8 new plugins in docs/designs/.

Phase 3: Scaffold 8 new plugins — saas-api-platform, saas-db-migrate,
saas-react-platform, saas-test-pilot, data-seed, ops-release-manager,
ops-deploy-pipeline, debug-mcp. Each with plugin.json, commands, agents,
skills, README, and claude-md-integration. Marketplace grows from 12→20.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/saas-db-migrate/commands/db-migrate-validate.md

@@ -0,0 +1,127 @@
+---
+name: db-migrate validate
+description: Check migration safety before applying
+agent: migration-auditor
+---
+
+# /db-migrate validate - Migration Safety Validator
+
+## Skills to Load
+
+- skills/migration-safety.md
+- skills/visual-header.md
+
+## Visual Output
+
+Display header: `DB-MIGRATE - Validate`
+
+## Usage
+
+```
+/db-migrate validate [<migration-file>] [--all] [--strict]
+```
+
+**Arguments:**
+- `<migration-file>`: Specific migration to validate (default: latest unapplied)
+- `--all`: Validate all unapplied migrations
+- `--strict`: Treat warnings as errors
+
+## Prerequisites
+
+Run `/db-migrate setup` first. Migration files must exist in the configured directory.
+
+## Process
+
+### 1. Identify Target Migrations
+
+Determine which migrations to validate:
+- Specific file if provided
+- All unapplied migrations if `--all`
+- Latest unapplied migration by default
+
+### 2. Parse Migration Operations
+
+Read each migration file and extract SQL operations:
+- Table creation/deletion
+- Column additions, modifications, removals
+- Index operations
+- Constraint changes
+- Data manipulation (INSERT, UPDATE, DELETE)
+- Custom SQL blocks
+
+### 3. Safety Analysis
+
+Apply safety rules from `skills/migration-safety.md`:
+
+| Check | Severity | Description |
+|-------|----------|-------------|
+| DROP TABLE | FAIL | Permanent data loss; requires explicit acknowledgment |
+| DROP COLUMN | FAIL | Data loss; must confirm column is unused |
+| ALTER COLUMN type (narrowing) | FAIL | Data truncation risk (e.g., VARCHAR(255) to VARCHAR(50)) |
+| ALTER COLUMN type (widening) | WARN | Safe but verify application handles new type |
+| ALTER COLUMN NOT NULL (existing data) | FAIL | May fail if NULLs exist; needs DEFAULT or backfill |
+| RENAME TABLE/COLUMN | WARN | Application code must be updated simultaneously |
+| Large table ALTER | WARN | May lock table for extended time; consider batching |
+| Missing transaction wrapper | FAIL | Partial migrations leave inconsistent state |
+| Missing rollback/downgrade | WARN | Cannot undo if problems occur |
+| Data migration in schema migration | WARN | Should be separate migration |
+| No-op migration | INFO | Migration has no effect |
+
+### 4. Lock Duration Estimation
+
+For ALTER operations on existing tables, estimate lock impact:
+- Table size (if database connection available)
+- Operation type (ADD COLUMN is instant in PostgreSQL, ALTER TYPE is not)
+- Concurrent operation risk
+
+### 5. Generate Report
+
+Group findings by severity with actionable recommendations.
+
+## Output Format
+
+```
++----------------------------------------------------------------------+
+|  DB-MIGRATE - Validate                                               |
++----------------------------------------------------------------------+
+
+Target: alembic/versions/b3c4d5e6_drop_legacy_columns.py
+Tool: Alembic
+
+FINDINGS
+
+FAIL (2)
+  1. DROP COLUMN users.legacy_email
+     Risk: Permanent data loss for 12,450 rows with values
+     Fix: Verify column is unused, add data backup step, or
+          rename column first and drop in a future migration
+
+  2. ALTER COLUMN orders.total VARCHAR(10) -> VARCHAR(5)
+     Risk: Data truncation for values longer than 5 characters
+     Fix: Check max actual length: SELECT MAX(LENGTH(total)) FROM orders
+          If safe, document in migration comment
+
+WARN (1)
+  1. Missing downgrade for DROP COLUMN
+     Risk: Cannot rollback this migration
+     Fix: Add downgrade() that re-creates column (data will be lost)
+
+INFO (1)
+  1. Migration includes both schema and data changes
+     Suggestion: Separate into two migrations for cleaner rollback
+
+SUMMARY
+  Operations:   4 (2 DDL, 2 DML)
+  FAIL:         2 (must fix before applying)
+  WARN:         1 (should fix)
+  INFO:         1 (improve)
+
+VERDICT: FAIL (2 blocking issues)
+```
+
+## Exit Guidance
+
+- FAIL: Do not apply migration until issues are resolved
+- WARN: Review carefully; proceed with caution
+- INFO: Suggestions for improvement; safe to proceed
+- `--strict`: All WARN become FAIL