fix(extensions): preserve existing MCP servers

TODO.md

@@ -5,7 +5,7 @@
 - [x] Validate every path read from `.ai-config-manifest.tsv` and reject links before backup, overwrite, or removal. Both manifest writers join unchecked recorded paths to the destination; a `../` entry or linked target can reach files outside the managed directory. (`scripts/lib/manifest.ps1:20`, `scripts/lib/manifest.ps1:136`, `scripts/lib/manifest.sh:20`, `scripts/lib/manifest.sh:170`)
 - [x] Keep an installed semantic retrieval runtime when an `auto` benchmark says no. `benchmark()` deletes the whole runtime and ownership state even when `state['clients']` still contains active clients. (`scripts/lib/semantic-retrieval.py:117`, `scripts/lib/semantic-retrieval.py:142`)
 - [x] Check semantic retrieval ownership and links before copying or deleting its directory. An existing owned runtime's source files are overwritten without comparing recorded hashes; a replaced target symlink is followed on enable, and disabling the last client removes foreign files inside the runtime. (`scripts/lib/semantic-retrieval.py:82`, `scripts/lib/semantic-retrieval.py:100`)
-- [ ] Preserve pre-existing MCPorter server entries. `ensure_mcporter()` adds a server and claims ownership without checking existing configuration; if the add succeeds for an existing name, a later removal deletes that user's entry. (`scripts/lib/managed-extensions.py:395`, `scripts/lib/managed-extensions.py:263`)
+- [x] Preserve pre-existing MCPorter server entries. `ensure_mcporter()` adds a server and claims ownership without checking existing configuration; if the add succeeds for an existing name, a later removal deletes that user's entry. (`scripts/lib/managed-extensions.py:395`, `scripts/lib/managed-extensions.py:263`)
 - [ ] Preserve pre-existing global CLI packages. `ensure_cli()` and `ensure_qmd()` install and claim npm packages without checking whether they were already installed; later removal can uninstall a user's package. (`scripts/lib/managed-extensions.py:342`, `scripts/lib/managed-extensions.py:378`)
 - [x] Fetch skill archives by an immutable commit and record that same commit. The archive uses GitHub `HEAD`, while `resolvedRevision` comes from a separate later request, so the recorded revision may not identify the installed payload. (`scripts/lib/managed-extensions.py:94`, `scripts/lib/managed-extensions.py:140`, `scripts/lib/managed-extensions.py:409`)
 - [x] Protect the semantic retrieval daemon's IPC protocol. It uses a hardcoded authentication key and `multiprocessing.connection.recv()`, which deserializes messages; a process that can reach its socket or pipe can submit arbitrary roots and potentially crafted objects. Use a private per-install credential and a non-pickle wire format, or restrict the endpoint to the current user. (`shared/retrieval/server.py:47`, `shared/retrieval/server.py:306`, `shared/retrieval/server.py:314`)

scripts/lib/managed-extensions.py

@@ -401,6 +401,20 @@ class Manager:
         if not re.fullmatch(r'[a-z0-9-]+', server) or not re.fullmatch(r'https://[^\s]+', url):
             raise ValueError('Invalid MCPorter server definition.')
         record = next((r for r in self.state['resources'] if r['client'] == 'shared' and r['name'] == entry['name']), None)
+        config_path = safe_path(self.home, '.mcporter/mcporter.json')
+        if config_path.exists():
+            config = json.loads(config_path.read_text(encoding='utf-8'))
+            if not isinstance(config, dict) or not isinstance(config.get('mcpServers', {}), dict):
+                raise ValueError('Invalid MCPorter server configuration.')
+            existing = config.get('mcpServers', {}).get(server)
+            if existing is not None and not isinstance(existing, dict):
+                raise ValueError('Invalid MCPorter server entry.')
+            if existing is not None and record is None:
+                if not self.summary:
+                    print(f'PASS Preserving pre-existing MCPorter server: {server}')
+                return
+            if existing is not None and record is not None and existing.get('baseUrl') != record['url']:
+                raise ValueError('Owned MCPorter server changed locally; refusing to overwrite it.')
         if record is not None and not self.update:
             return
         self.command(['mcporter', '--config', str(self.home / '.mcporter/mcporter.json'), 'config', 'add', server, url])