diff --git a/.claude-plugin/marketplace.json b/.claude-plugin/marketplace.json
index e302985..62ce7e2 100644
--- a/.claude-plugin/marketplace.json
+++ b/.claude-plugin/marketplace.json
@@ -6,7 +6,7 @@
   },
   "metadata": {
     "description": "Project management plugins with Gitea and NetBox integrations",
-    "version": "9.1.1"
+    "version": "9.1.2"
   },
   "plugins": [
     {
@@ -27,8 +27,7 @@
         "gitea",
         "project-management"
       ],
-      "license": "MIT",
-      "domain": "core"
+      "license": "MIT"
     },
     {
       "name": "doc-guardian",
@@ -47,8 +46,7 @@
         "drift-detection",
         "sync"
       ],
-      "license": "MIT",
-      "domain": "core"
+      "license": "MIT"
     },
     {
       "name": "code-sentinel",
@@ -70,8 +68,7 @@
         "refactoring",
         "vulnerabilities"
       ],
-      "license": "MIT",
-      "domain": "core"
+      "license": "MIT"
     },
     {
       "name": "project-hygiene",
@@ -91,8 +88,7 @@
         "maintenance",
         "manual-check"
       ],
-      "license": "MIT",
-      "domain": "core"
+      "license": "MIT"
     },
     {
       "name": "cmdb-assistant",
@@ -117,8 +113,7 @@
         "data-quality",
         "validation"
       ],
-      "license": "MIT",
-      "domain": "ops"
+      "license": "MIT"
     },
     {
       "name": "claude-config-maintainer",
@@ -137,8 +132,7 @@
         "configuration",
         "optimization"
       ],
-      "license": "MIT",
-      "domain": "core"
+      "license": "MIT"
     },
     {
       "name": "clarity-assist",
@@ -161,8 +155,7 @@
         "clarification",
         "nd-friendly"
       ],
-      "license": "MIT",
-      "domain": "core"
+      "license": "MIT"
     },
     {
       "name": "git-flow",
@@ -185,8 +178,7 @@
         "commits",
         "branching"
       ],
-      "license": "MIT",
-      "domain": "core"
+      "license": "MIT"
     },
     {
       "name": "pr-review",
@@ -206,8 +198,7 @@
         "security",
         "quality"
       ],
-      "license": "MIT",
-      "domain": "core"
+      "license": "MIT"
     },
     {
       "name": "data-platform",
@@ -229,8 +220,7 @@
         "data-engineering",
         "etl"
       ],
-      "license": "MIT",
-      "domain": "data"
+      "license": "MIT"
     },
     {
       "name": "viz-platform",
@@ -253,8 +243,7 @@
         "theming",
         "dmc"
       ],
-      "license": "MIT",
-      "domain": "data"
+      "license": "MIT"
     },
     {
       "name": "contract-validator",
@@ -276,8 +265,7 @@
         "interfaces",
         "cross-plugin"
       ],
-      "license": "MIT",
-      "domain": "core"
+      "license": "MIT"
     },
     {
       "name": "saas-api-platform",
@@ -299,8 +287,7 @@
         "express",
         "openapi"
       ],
-      "license": "MIT",
-      "domain": "saas"
+      "license": "MIT"
     },
     {
       "name": "saas-db-migrate",
@@ -322,8 +309,7 @@
         "sql",
         "schema"
       ],
-      "license": "MIT",
-      "domain": "saas"
+      "license": "MIT"
     },
     {
       "name": "saas-react-platform",
@@ -345,8 +331,7 @@
         "frontend",
         "components"
       ],
-      "license": "MIT",
-      "domain": "saas"
+      "license": "MIT"
     },
     {
       "name": "saas-test-pilot",
@@ -368,8 +353,7 @@
         "playwright",
         "coverage"
       ],
-      "license": "MIT",
-      "domain": "saas"
+      "license": "MIT"
     },
     {
       "name": "data-seed",
@@ -390,8 +374,7 @@
         "fixtures",
         "database"
       ],
-      "license": "MIT",
-      "domain": "data"
+      "license": "MIT"
     },
     {
       "name": "ops-release-manager",
@@ -412,8 +395,7 @@
         "versioning",
         "tags"
       ],
-      "license": "MIT",
-      "domain": "ops"
+      "license": "MIT"
     },
     {
       "name": "ops-deploy-pipeline",
@@ -434,8 +416,7 @@
         "caddy",
         "cicd"
       ],
-      "license": "MIT",
-      "domain": "ops"
+      "license": "MIT"
     },
     {
       "name": "debug-mcp",
@@ -456,8 +437,7 @@
         "server",
         "development"
       ],
-      "license": "MIT",
-      "domain": "debug"
+      "license": "MIT"
     }
   ]
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c44caca..2390bef 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,15 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+## [9.1.2] - 2026-02-07
+
+### Fixed
+
+- **BREAKING FIX:** Removed `"domain"` field from all `marketplace.json` and `plugin.json` files — Claude Code's strict schema validator rejects unrecognized keys, causing `Failed to load marketplace` error
+- Domain metadata moved to `metadata.json` per plugin (same pattern as `mcp_servers`)
+- `validate-marketplace.sh` updated to read domain from `metadata.json` instead of `marketplace.json`/`plugin.json`
+- All documentation updated to reference `metadata.json` as domain source
+
 ## [9.1.1] - 2026-02-07
 
 ### Changed
diff --git a/CLAUDE.md b/CLAUDE.md
index f54b407..ccb303e 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -154,7 +154,7 @@ When user says "fix the sprint plan command", edit the SOURCE code.
 ## Project Overview
 
 **Repository:** leo-claude-mktplace
-**Version:** 9.1.1
+**Version:** 9.1.2
 **Status:** Production Ready
 
 A plugin marketplace for Claude Code containing:
@@ -424,19 +424,18 @@ Stored in Gitea Wiki under `lessons-learned/sprints/`.
 
 ### Adding a New Plugin
 
-1. Create `plugins/{name}/.claude-plugin/plugin.json` — must include `"domain"` field (`core`, `data`, `saas`, `ops`, or `debug`)
-2. Add entry to `.claude-plugin/marketplace.json` with category, tags, license, and `"domain"` field (must match plugin.json)
-3. Create `claude-md-integration.md`
-4. If using new MCP server, add to root `mcp-servers/` and update `.mcp.json`
-5. Run `./scripts/validate-marketplace.sh` — rejects plugins without valid `domain` field
-6. Update `CHANGELOG.md`
+1. Create `plugins/{name}/.claude-plugin/plugin.json` (standard schema fields only — no custom fields)
+2. Create `plugins/{name}/.claude-plugin/metadata.json` — must include `"domain"` field (`core`, `data`, `saas`, `ops`, or `debug`)
+3. Add entry to `.claude-plugin/marketplace.json` with category, tags, license (no custom fields — Claude Code schema is strict)
+4. Create `claude-md-integration.md`
+5. If using new MCP server, add to root `mcp-servers/` and update `.mcp.json`
+6. Run `./scripts/validate-marketplace.sh` — rejects plugins without valid `domain` field
+7. Update `CHANGELOG.md`
 
-**Domain field is required (v8.0.0+):**
+**Domain field is required in metadata.json (v8.0.0+, moved from plugin.json in v9.1.2):**
 ```json
 {
-  "name": "plugin-name",
-  "domain": "core",
-  ...
+  "domain": "core"
 }
 ```
 
diff --git a/README.md b/README.md
index 73ed04e..7aabb7b 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# Leo Claude Marketplace — v9.1.1
+# Leo Claude Marketplace — v9.1.2
 
 A plugin marketplace for Claude Code providing sprint management, code review, security scanning, infrastructure automation, and development workflow tools. 20 plugins across 5 domains, backed by 5 shared MCP servers.
 
diff --git a/docs/CANONICAL-PATHS.md b/docs/CANONICAL-PATHS.md
index 2ac5a56..5254ca4 100644
--- a/docs/CANONICAL-PATHS.md
+++ b/docs/CANONICAL-PATHS.md
@@ -384,14 +384,13 @@ All MCP servers are defined in `.mcp.json` at repository root:
 
 ## Domain Metadata
 
-### Domain Field Locations
+### Domain Field Location
 
-Both manifest files require a `domain` field (v8.0.0+):
+Domain metadata is stored in `metadata.json` (v9.1.2+, moved from plugin.json/marketplace.json for Claude Code schema compliance):
 
 | Location | Field | Example |
 |----------|-------|---------|
-| `plugins/{name}/.claude-plugin/plugin.json` | `"domain": "core"` | `plugins/projman/.claude-plugin/plugin.json` |
-| `.claude-plugin/marketplace.json` | `"domain": "core"` per plugin entry | `.claude-plugin/marketplace.json` |
+| `plugins/{name}/.claude-plugin/metadata.json` | `"domain": "core"` | `plugins/projman/.claude-plugin/metadata.json` |
 
 ### Allowed Domain Values
 
@@ -413,10 +412,15 @@ Both manifest files require a `domain` field (v8.0.0+):
 
 ```bash
 # List all plugins in a domain
-jq '.plugins[] | select(.domain=="saas") | .name' .claude-plugin/marketplace.json
+for p in plugins/*; do
+  d=$(jq -r '.domain // empty' "$p/.claude-plugin/metadata.json" 2>/dev/null)
+  [[ "$d" == "saas" ]] && basename "$p"
+done
 
 # Count plugins per domain
-jq '[.plugins[] | .domain] | group_by(.) | map({domain: .[0], count: length})' .claude-plugin/marketplace.json
+for p in plugins/*; do
+  jq -r '.domain // empty' "$p/.claude-plugin/metadata.json" 2>/dev/null
+done | sort | uniq -c | sort -rn
 ```
 
 ---
@@ -425,6 +429,7 @@ jq '[.plugins[] | .domain] | group_by(.) | map({domain: .[0], count: length})' .
 
 | Date | Change | By |
 |------|--------|-----|
+| 2026-02-07 | v9.1.2: Moved domain field from plugin.json/marketplace.json to metadata.json for Claude Code schema compliance | Claude Code |
 | 2026-02-07 | v9.1.0: Removed deleted dirs (architecture/, prompts/, project-lessons-learned/), added Phase 3 plugins, added ARCHITECTURE.md, MIGRATION-v9.md, updated Domain table, removed stale hooks/ dirs | Claude Code |
 | 2026-02-06 | v8.0.0: Added domain metadata section, Phase 1a paths, future plugin paths | Claude Code |
 | 2026-02-04 | v7.1.0: Added profile configs, prompts/, project-lessons-learned/, metadata.json, deprecated switch-profile.sh | Claude Code |
diff --git a/plugins/clarity-assist/.claude-plugin/metadata.json b/plugins/clarity-assist/.claude-plugin/metadata.json
new file mode 100644
index 0000000..f99a72a
--- /dev/null
+++ b/plugins/clarity-assist/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "core"
+}
diff --git a/plugins/clarity-assist/.claude-plugin/plugin.json b/plugins/clarity-assist/.claude-plugin/plugin.json
index 54f794b..be23302 100644
--- a/plugins/clarity-assist/.claude-plugin/plugin.json
+++ b/plugins/clarity-assist/.claude-plugin/plugin.json
@@ -18,6 +18,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "core"
+  ]
 }
diff --git a/plugins/claude-config-maintainer/.claude-plugin/metadata.json b/plugins/claude-config-maintainer/.claude-plugin/metadata.json
new file mode 100644
index 0000000..f99a72a
--- /dev/null
+++ b/plugins/claude-config-maintainer/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "core"
+}
diff --git a/plugins/claude-config-maintainer/.claude-plugin/plugin.json b/plugins/claude-config-maintainer/.claude-plugin/plugin.json
index 48d08a0..9cc437c 100644
--- a/plugins/claude-config-maintainer/.claude-plugin/plugin.json
+++ b/plugins/claude-config-maintainer/.claude-plugin/plugin.json
@@ -20,6 +20,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "core"
+  ]
 }
diff --git a/plugins/cmdb-assistant/.claude-plugin/metadata.json b/plugins/cmdb-assistant/.claude-plugin/metadata.json
index 3a90799..ba79054 100644
--- a/plugins/cmdb-assistant/.claude-plugin/metadata.json
+++ b/plugins/cmdb-assistant/.claude-plugin/metadata.json
@@ -1 +1,6 @@
-{"mcp_servers": ["netbox"]}
+{
+  "mcp_servers": [
+    "netbox"
+  ],
+  "domain": "ops"
+}
diff --git a/plugins/cmdb-assistant/.claude-plugin/plugin.json b/plugins/cmdb-assistant/.claude-plugin/plugin.json
index 01fc239..76032dd 100644
--- a/plugins/cmdb-assistant/.claude-plugin/plugin.json
+++ b/plugins/cmdb-assistant/.claude-plugin/plugin.json
@@ -21,6 +21,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "ops"
+  ]
 }
diff --git a/plugins/code-sentinel/.claude-plugin/metadata.json b/plugins/code-sentinel/.claude-plugin/metadata.json
new file mode 100644
index 0000000..f99a72a
--- /dev/null
+++ b/plugins/code-sentinel/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "core"
+}
diff --git a/plugins/code-sentinel/.claude-plugin/plugin.json b/plugins/code-sentinel/.claude-plugin/plugin.json
index 9600990..39fb079 100644
--- a/plugins/code-sentinel/.claude-plugin/plugin.json
+++ b/plugins/code-sentinel/.claude-plugin/plugin.json
@@ -18,6 +18,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "core"
+  ]
 }
diff --git a/plugins/contract-validator/.claude-plugin/metadata.json b/plugins/contract-validator/.claude-plugin/metadata.json
index 11632cc..b21415b 100644
--- a/plugins/contract-validator/.claude-plugin/metadata.json
+++ b/plugins/contract-validator/.claude-plugin/metadata.json
@@ -1 +1,6 @@
-{"mcp_servers": ["contract-validator"]}
+{
+  "mcp_servers": [
+    "contract-validator"
+  ],
+  "domain": "core"
+}
diff --git a/plugins/contract-validator/.claude-plugin/plugin.json b/plugins/contract-validator/.claude-plugin/plugin.json
index 9515ed2..04fab1e 100644
--- a/plugins/contract-validator/.claude-plugin/plugin.json
+++ b/plugins/contract-validator/.claude-plugin/plugin.json
@@ -19,6 +19,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "core"
+  ]
 }
diff --git a/plugins/data-platform/.claude-plugin/metadata.json b/plugins/data-platform/.claude-plugin/metadata.json
index 59da561..b7dd4e6 100644
--- a/plugins/data-platform/.claude-plugin/metadata.json
+++ b/plugins/data-platform/.claude-plugin/metadata.json
@@ -1 +1,6 @@
-{"mcp_servers": ["data-platform"]}
+{
+  "mcp_servers": [
+    "data-platform"
+  ],
+  "domain": "data"
+}
diff --git a/plugins/data-platform/.claude-plugin/plugin.json b/plugins/data-platform/.claude-plugin/plugin.json
index b2f5166..39ba963 100644
--- a/plugins/data-platform/.claude-plugin/plugin.json
+++ b/plugins/data-platform/.claude-plugin/plugin.json
@@ -20,6 +20,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "data"
+  ]
 }
diff --git a/plugins/data-seed/.claude-plugin/metadata.json b/plugins/data-seed/.claude-plugin/metadata.json
new file mode 100644
index 0000000..07d315c
--- /dev/null
+++ b/plugins/data-seed/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "data"
+}
diff --git a/plugins/data-seed/.claude-plugin/plugin.json b/plugins/data-seed/.claude-plugin/plugin.json
index 659325d..72d976d 100644
--- a/plugins/data-seed/.claude-plugin/plugin.json
+++ b/plugins/data-seed/.claude-plugin/plugin.json
@@ -20,6 +20,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "data"
+  ]
 }
diff --git a/plugins/debug-mcp/.claude-plugin/metadata.json b/plugins/debug-mcp/.claude-plugin/metadata.json
new file mode 100644
index 0000000..fc629a6
--- /dev/null
+++ b/plugins/debug-mcp/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "debug"
+}
diff --git a/plugins/debug-mcp/.claude-plugin/plugin.json b/plugins/debug-mcp/.claude-plugin/plugin.json
index 08303ba..fbb4c77 100644
--- a/plugins/debug-mcp/.claude-plugin/plugin.json
+++ b/plugins/debug-mcp/.claude-plugin/plugin.json
@@ -20,6 +20,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "debug"
+  ]
 }
diff --git a/plugins/doc-guardian/.claude-plugin/metadata.json b/plugins/doc-guardian/.claude-plugin/metadata.json
index a352e4a..9af4ef0 100644
--- a/plugins/doc-guardian/.claude-plugin/metadata.json
+++ b/plugins/doc-guardian/.claude-plugin/metadata.json
@@ -1 +1,6 @@
-{"mcp_servers": ["gitea"]}
+{
+  "mcp_servers": [
+    "gitea"
+  ],
+  "domain": "core"
+}
diff --git a/plugins/doc-guardian/.claude-plugin/plugin.json b/plugins/doc-guardian/.claude-plugin/plugin.json
index 1ba3635..deae60b 100644
--- a/plugins/doc-guardian/.claude-plugin/plugin.json
+++ b/plugins/doc-guardian/.claude-plugin/plugin.json
@@ -18,6 +18,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "core"
+  ]
 }
diff --git a/plugins/git-flow/.claude-plugin/metadata.json b/plugins/git-flow/.claude-plugin/metadata.json
index a352e4a..9af4ef0 100644
--- a/plugins/git-flow/.claude-plugin/metadata.json
+++ b/plugins/git-flow/.claude-plugin/metadata.json
@@ -1 +1,6 @@
-{"mcp_servers": ["gitea"]}
+{
+  "mcp_servers": [
+    "gitea"
+  ],
+  "domain": "core"
+}
diff --git a/plugins/git-flow/.claude-plugin/plugin.json b/plugins/git-flow/.claude-plugin/plugin.json
index 9559b42..b0043e8 100644
--- a/plugins/git-flow/.claude-plugin/plugin.json
+++ b/plugins/git-flow/.claude-plugin/plugin.json
@@ -18,6 +18,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "core"
+  ]
 }
diff --git a/plugins/ops-deploy-pipeline/.claude-plugin/metadata.json b/plugins/ops-deploy-pipeline/.claude-plugin/metadata.json
new file mode 100644
index 0000000..06a6c26
--- /dev/null
+++ b/plugins/ops-deploy-pipeline/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "ops"
+}
diff --git a/plugins/ops-deploy-pipeline/.claude-plugin/plugin.json b/plugins/ops-deploy-pipeline/.claude-plugin/plugin.json
index 13165b4..fa59704 100644
--- a/plugins/ops-deploy-pipeline/.claude-plugin/plugin.json
+++ b/plugins/ops-deploy-pipeline/.claude-plugin/plugin.json
@@ -20,6 +20,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "ops"
+  ]
 }
diff --git a/plugins/ops-release-manager/.claude-plugin/metadata.json b/plugins/ops-release-manager/.claude-plugin/metadata.json
new file mode 100644
index 0000000..06a6c26
--- /dev/null
+++ b/plugins/ops-release-manager/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "ops"
+}
diff --git a/plugins/ops-release-manager/.claude-plugin/plugin.json b/plugins/ops-release-manager/.claude-plugin/plugin.json
index 44e2e58..46db311 100644
--- a/plugins/ops-release-manager/.claude-plugin/plugin.json
+++ b/plugins/ops-release-manager/.claude-plugin/plugin.json
@@ -20,6 +20,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "ops"
+  ]
 }
diff --git a/plugins/pr-review/.claude-plugin/metadata.json b/plugins/pr-review/.claude-plugin/metadata.json
index a352e4a..9af4ef0 100644
--- a/plugins/pr-review/.claude-plugin/metadata.json
+++ b/plugins/pr-review/.claude-plugin/metadata.json
@@ -1 +1,6 @@
-{"mcp_servers": ["gitea"]}
+{
+  "mcp_servers": [
+    "gitea"
+  ],
+  "domain": "core"
+}
diff --git a/plugins/pr-review/.claude-plugin/plugin.json b/plugins/pr-review/.claude-plugin/plugin.json
index 12edf84..25b336f 100644
--- a/plugins/pr-review/.claude-plugin/plugin.json
+++ b/plugins/pr-review/.claude-plugin/plugin.json
@@ -18,6 +18,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "core"
+  ]
 }
diff --git a/plugins/project-hygiene/.claude-plugin/metadata.json b/plugins/project-hygiene/.claude-plugin/metadata.json
new file mode 100644
index 0000000..f99a72a
--- /dev/null
+++ b/plugins/project-hygiene/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "core"
+}
diff --git a/plugins/project-hygiene/.claude-plugin/plugin.json b/plugins/project-hygiene/.claude-plugin/plugin.json
index dcca84c..e7559ba 100644
--- a/plugins/project-hygiene/.claude-plugin/plugin.json
+++ b/plugins/project-hygiene/.claude-plugin/plugin.json
@@ -15,7 +15,6 @@
     "maintenance",
     "manual-check"
   ],
-  "domain": "core",
   "commands": [
     "./commands/"
   ]
diff --git a/plugins/projman/.claude-plugin/metadata.json b/plugins/projman/.claude-plugin/metadata.json
index a352e4a..9af4ef0 100644
--- a/plugins/projman/.claude-plugin/metadata.json
+++ b/plugins/projman/.claude-plugin/metadata.json
@@ -1 +1,6 @@
-{"mcp_servers": ["gitea"]}
+{
+  "mcp_servers": [
+    "gitea"
+  ],
+  "domain": "core"
+}
diff --git a/plugins/projman/.claude-plugin/plugin.json b/plugins/projman/.claude-plugin/plugin.json
index cc49851..008fc01 100644
--- a/plugins/projman/.claude-plugin/plugin.json
+++ b/plugins/projman/.claude-plugin/plugin.json
@@ -18,6 +18,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "core"
+  ]
 }
diff --git a/plugins/saas-api-platform/.claude-plugin/metadata.json b/plugins/saas-api-platform/.claude-plugin/metadata.json
new file mode 100644
index 0000000..1ed9b8f
--- /dev/null
+++ b/plugins/saas-api-platform/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "saas"
+}
diff --git a/plugins/saas-api-platform/.claude-plugin/plugin.json b/plugins/saas-api-platform/.claude-plugin/plugin.json
index 32abbf8..a8ef6f4 100644
--- a/plugins/saas-api-platform/.claude-plugin/plugin.json
+++ b/plugins/saas-api-platform/.claude-plugin/plugin.json
@@ -21,6 +21,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "saas"
+  ]
 }
diff --git a/plugins/saas-db-migrate/.claude-plugin/metadata.json b/plugins/saas-db-migrate/.claude-plugin/metadata.json
new file mode 100644
index 0000000..1ed9b8f
--- /dev/null
+++ b/plugins/saas-db-migrate/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "saas"
+}
diff --git a/plugins/saas-db-migrate/.claude-plugin/plugin.json b/plugins/saas-db-migrate/.claude-plugin/plugin.json
index c169f77..6445238 100644
--- a/plugins/saas-db-migrate/.claude-plugin/plugin.json
+++ b/plugins/saas-db-migrate/.claude-plugin/plugin.json
@@ -20,6 +20,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "saas"
+  ]
 }
diff --git a/plugins/saas-react-platform/.claude-plugin/metadata.json b/plugins/saas-react-platform/.claude-plugin/metadata.json
new file mode 100644
index 0000000..1ed9b8f
--- /dev/null
+++ b/plugins/saas-react-platform/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "saas"
+}
diff --git a/plugins/saas-react-platform/.claude-plugin/plugin.json b/plugins/saas-react-platform/.claude-plugin/plugin.json
index 7948e92..1e2a29a 100644
--- a/plugins/saas-react-platform/.claude-plugin/plugin.json
+++ b/plugins/saas-react-platform/.claude-plugin/plugin.json
@@ -21,6 +21,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "saas"
+  ]
 }
diff --git a/plugins/saas-test-pilot/.claude-plugin/metadata.json b/plugins/saas-test-pilot/.claude-plugin/metadata.json
new file mode 100644
index 0000000..1ed9b8f
--- /dev/null
+++ b/plugins/saas-test-pilot/.claude-plugin/metadata.json
@@ -0,0 +1,3 @@
+{
+  "domain": "saas"
+}
diff --git a/plugins/saas-test-pilot/.claude-plugin/plugin.json b/plugins/saas-test-pilot/.claude-plugin/plugin.json
index e5a3ac9..06a2a17 100644
--- a/plugins/saas-test-pilot/.claude-plugin/plugin.json
+++ b/plugins/saas-test-pilot/.claude-plugin/plugin.json
@@ -21,6 +21,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "saas"
+  ]
 }
diff --git a/plugins/viz-platform/.claude-plugin/metadata.json b/plugins/viz-platform/.claude-plugin/metadata.json
index 3b6981d..4d82a2f 100644
--- a/plugins/viz-platform/.claude-plugin/metadata.json
+++ b/plugins/viz-platform/.claude-plugin/metadata.json
@@ -1 +1,6 @@
-{"mcp_servers": ["viz-platform"]}
+{
+  "mcp_servers": [
+    "viz-platform"
+  ],
+  "domain": "data"
+}
diff --git a/plugins/viz-platform/.claude-plugin/plugin.json b/plugins/viz-platform/.claude-plugin/plugin.json
index c85810b..e2e4424 100644
--- a/plugins/viz-platform/.claude-plugin/plugin.json
+++ b/plugins/viz-platform/.claude-plugin/plugin.json
@@ -21,6 +21,5 @@
   ],
   "commands": [
     "./commands/"
-  ],
-  "domain": "data"
+  ]
 }
diff --git a/scripts/validate-marketplace.sh b/scripts/validate-marketplace.sh
index aa57c2d..4787655 100755
--- a/scripts/validate-marketplace.sh
+++ b/scripts/validate-marketplace.sh
@@ -92,17 +92,23 @@ for i in $(seq 0 $((PLUGIN_COUNT - 1))); do
         exit 1
     fi
 
-    # v8.0.0: Check domain field
-    PLUGIN_DOMAIN=$(jq -r ".plugins[$i].domain // empty" "$MARKETPLACE_JSON")
+    # v8.0.0/v9.1.2: Check domain field in metadata.json (moved from marketplace.json for schema compliance)
+    PLUGIN_SOURCE=$(jq -r ".plugins[$i].source" "$MARKETPLACE_JSON")
+    METADATA_JSON="$ROOT_DIR/$PLUGIN_SOURCE/.claude-plugin/metadata.json"
+    if [[ -f "$METADATA_JSON" ]]; then
+        PLUGIN_DOMAIN=$(jq -r '.domain // empty' "$METADATA_JSON")
+    else
+        PLUGIN_DOMAIN=""
+    fi
     if [[ -z "$PLUGIN_DOMAIN" ]]; then
-        echo "ERROR: Missing 'domain' in marketplace entry for $PLUGIN_NAME (required v8.0.0+)"
+        echo "ERROR: Missing 'domain' in $PLUGIN_NAME/.claude-plugin/metadata.json (required v8.0.0+)"
         exit 1
     fi
     if ! echo "$VALID_DOMAINS" | grep -qw "$PLUGIN_DOMAIN"; then
-        echo "ERROR: Invalid domain '$PLUGIN_DOMAIN' in marketplace entry for $PLUGIN_NAME (allowed: $VALID_DOMAINS)"
+        echo "ERROR: Invalid domain '$PLUGIN_DOMAIN' in $PLUGIN_NAME/metadata.json (allowed: $VALID_DOMAINS)"
         exit 1
     fi
-    echo "  ✓ domain: $PLUGIN_DOMAIN"
+    echo "  ✓ domain: $PLUGIN_DOMAIN (from metadata.json)"
 
     echo "✓ Marketplace entry $PLUGIN_NAME valid"
 done
@@ -158,17 +164,22 @@ for plugin_dir in "$PLUGINS_DIR"/*/; do
         echo "WARNING: Missing 'keywords' array in $plugin_name/plugin.json"
     fi
 
-    # v8.0.0: Check domain field in plugin.json
-    PLUGIN_DOMAIN_PJ=$(jq -r '.domain // empty' "$plugin_json")
-    if [[ -z "$PLUGIN_DOMAIN_PJ" ]]; then
-        echo "ERROR: Missing 'domain' in $plugin_name/plugin.json (required v8.0.0+)"
+    # v8.0.0/v9.1.2: Check domain field in metadata.json (moved from plugin.json for schema compliance)
+    metadata_json="$plugin_dir.claude-plugin/metadata.json"
+    if [[ -f "$metadata_json" ]]; then
+        PLUGIN_DOMAIN_MD=$(jq -r '.domain // empty' "$metadata_json")
+    else
+        PLUGIN_DOMAIN_MD=""
+    fi
+    if [[ -z "$PLUGIN_DOMAIN_MD" ]]; then
+        echo "ERROR: Missing 'domain' in $plugin_name/.claude-plugin/metadata.json (required v8.0.0+)"
         exit 1
     fi
-    if ! echo "$VALID_DOMAINS" | grep -qw "$PLUGIN_DOMAIN_PJ"; then
-        echo "ERROR: Invalid domain '$PLUGIN_DOMAIN_PJ' in $plugin_name/plugin.json (allowed: $VALID_DOMAINS)"
+    if ! echo "$VALID_DOMAINS" | grep -qw "$PLUGIN_DOMAIN_MD"; then
+        echo "ERROR: Invalid domain '$PLUGIN_DOMAIN_MD' in $plugin_name/metadata.json (allowed: $VALID_DOMAINS)"
         exit 1
     fi
-    echo "  ✓ domain: $PLUGIN_DOMAIN_PJ"
+    echo "  ✓ domain: $PLUGIN_DOMAIN_MD (from metadata.json)"
 
     # Check README exists
     if [[ ! -f "$plugin_dir/README.md" ]]; then
@@ -324,20 +335,23 @@ if [[ ! -f "$ROOT_DIR/.mcp.json" ]]; then
 fi
 echo "✓ .mcp.json configuration exists"
 
-# v8.0.0: Cross-validate domains match between marketplace.json and plugin.json
+# v8.0.0/v9.1.2: Validate domain in metadata.json for all plugins (single source of truth)
 echo ""
-echo "=== Cross-Validating Domain Fields ==="
-for i in $(seq 0 $((PLUGIN_COUNT - 1))); do
-    PLUGIN_NAME=$(jq -r ".plugins[$i].name" "$MARKETPLACE_JSON")
-    MARKETPLACE_DOMAIN=$(jq -r ".plugins[$i].domain" "$MARKETPLACE_JSON")
-    PLUGIN_JSON_PATH="$PLUGINS_DIR/$PLUGIN_NAME/.claude-plugin/plugin.json"
-    if [[ -f "$PLUGIN_JSON_PATH" ]]; then
-        PLUGIN_DOMAIN=$(jq -r '.domain' "$PLUGIN_JSON_PATH")
-        if [[ "$MARKETPLACE_DOMAIN" != "$PLUGIN_DOMAIN" ]]; then
-            echo "ERROR: Domain mismatch for $PLUGIN_NAME: marketplace.json='$MARKETPLACE_DOMAIN' vs plugin.json='$PLUGIN_DOMAIN'"
+echo "=== Validating Domain Fields (metadata.json) ==="
+for plugin_dir in "$PLUGINS_DIR"/*/; do
+    plugin_name=$(basename "$plugin_dir")
+    metadata_file="$plugin_dir.claude-plugin/metadata.json"
+    if [[ -f "$metadata_file" ]]; then
+        domain=$(jq -r '.domain // empty' "$metadata_file")
+        if [[ -n "$domain" ]]; then
+            echo "✓ $plugin_name domain: $domain"
+        else
+            echo "ERROR: $plugin_name/metadata.json exists but missing domain field"
             exit 1
         fi
-        echo "✓ $PLUGIN_NAME domain consistent: $MARKETPLACE_DOMAIN"
+    else
+        echo "ERROR: $plugin_name missing .claude-plugin/metadata.json"
+        exit 1
     fi
 done