diff --git a/docs/codebase-summary.md b/docs/codebase-summary.md
index df29f733..17ae9fca 100644
--- a/docs/codebase-summary.md
+++ b/docs/codebase-summary.md
@@ -1,6 +1,6 @@
 # CCS Codebase Summary
 
-Last Updated: 2026-03-17
+Last Updated: 2026-03-18
 
 Comprehensive overview of the modularized CCS codebase structure following the Phase 9 modularization effort (Settings, Analytics, Auth Monitor splits + Test Infrastructure), v7.1 Remote CLIProxy feature, v7.2 Kiro + GitHub Copilot (ghcp) OAuth providers, v7.14 Hybrid Quota Management, v7.34 Image Analysis Hook, and account-context validation hardening.
 
@@ -222,6 +222,13 @@ src/
   - API route rejects `context_group`/`continuity_mode` when mode is not `shared`
   - registry normalization drops malformed persisted `context_group` values
 
+### Shared Plugin Layout
+
+- Shared payload owner: `src/management/shared-manager.ts`.
+- Profile entry point: `src/management/instance-manager.ts`.
+- `plugins/marketplaces/`, `plugins/cache/`, and `installed_plugins.json` stay shared through the `~/.ccs/shared/` topology.
+- `known_marketplaces.json` is now instance-local under `~/.ccs/instances/<profile>/plugins/` so Claude Code validates `installLocation` against the active `CLAUDE_CONFIG_DIR` instead of a last-writer-wins shared file.
+
 ### Target Adapter Module
 
 The targets module provides an extensible interface for dispatching profiles to different CLI implementations.
diff --git a/docs/project-roadmap.md b/docs/project-roadmap.md
index 347851b2..ebaef666 100644
--- a/docs/project-roadmap.md
+++ b/docs/project-roadmap.md
@@ -1,6 +1,6 @@
 # CCS Project Roadmap
 
-Last Updated: 2026-03-17
+Last Updated: 2026-03-18
 
 Forward-looking roadmap documenting current priorities, GitHub issues, and future feature plans.
 
@@ -41,6 +41,7 @@ All major modularization work is complete. The codebase evolved from monolithic
 
 ### Recent Fixes
 
+- **2026-03-18**: **#755** Marketplace refresh no longer reuses one shared `known_marketplaces.json` across isolated instances. CCS now keeps marketplace payload directories shared while reconciling per-instance marketplace metadata so Claude Code validation succeeds for alternating or concurrent profiles, including Windows copy fallback.
 - **2026-03-17**: Deprecated user-facing GLMT discovery across CLI help, completions, presets, and docs. Existing `glmt` profiles now run through a compatibility path that normalizes legacy proxy settings to the direct GLM endpoint.
 - **#748**: API profile creation now keeps provider selection compact by collapsing advanced presets behind an explicit toggle, shrinking chooser cards so the form fields stay visually primary, and giving `llama.cpp` a dedicated provider logo.
 - **#744**: API profile creation now keeps featured providers in a horizontal rail with scroll fallback, moves Anthropic Direct API to the end, reuses the shared Claude logo, and separates the custom-endpoint entry point from advanced template discovery.
diff --git a/docs/system-architecture/index.md b/docs/system-architecture/index.md
index a13cd68e..7de060eb 100644
--- a/docs/system-architecture/index.md
+++ b/docs/system-architecture/index.md
@@ -1,6 +1,6 @@
 # CCS System Architecture
 
-Last Updated: 2026-03-02
+Last Updated: 2026-03-18
 
 High-level architecture overview for the CCS (Claude Code Switch) system.
 
@@ -233,12 +233,27 @@ For detailed provider flows (CLIProxyAPI, legacy GLMT compatibility, quota manag
             +---> commands/        # Claude Code commands
             +---> skills/          # Custom skills
             +---> agents/          # Agent configurations
+            +---> plugins/
+                    |
+                    +---> cache/               # Shared plugin payload/cache data
+                    +---> marketplaces/        # Shared marketplace payload directories
+                    +---> installed_plugins.json
+
+  ~/.ccs/instances/<profile>/
+    |
+    +---> plugins/
+            |
+            +---> known_marketplaces.json      # Instance-local registry for active CLAUDE_CONFIG_DIR validation
 
   ~/.factory/ (Droid CLI)
     |
     +---> settings.json            # Droid config (custom models)
 ```
 
+Plugin ownership note:
+- `commands/`, `skills/`, `agents/`, and `settings.json` remain shared through the existing symlink/copy flow.
+- Marketplace payload directories stay shared, but `known_marketplaces.json` is reconciled per instance so Claude Code can validate `installLocation` against that instance's `CLAUDE_CONFIG_DIR/plugins/marketplaces`.
+
 ### Config Loading Order
 
 ```