Add symf docs

docs/cody/core-concepts/keyword-search.mdx

@@ -4,6 +4,6 @@
 
 Keyword search is the traditional approach to text search. It splits content into terms and builds a mapping from terms to documents. At query time, it extracts terms from the query and uses the mapping to retrieve your documents.
 
-Both Cody chat and completions use Keyword Search. It comes out of the box without any additional setup. Cody with Keyword Search searches your local VS Code workspace and is a cost-effective and time-saving solution.
+Both Cody chat and completions use Keyword Search. It comes out of the box without any additional setup. Cody with Keyword Search searches your [local VS Code workspace](/cody/core-concepts/local-indexing) and is a cost-effective and time-saving solution.
 
 For an enterprise admin who has set up Cody with a Code Search instance, developers on their local machines can seamlessly access it.

docs/cody/core-concepts/local-indexing.mdx

@@ -0,0 +1,114 @@
+# Local Indexing
+
+<p className="subtitle">Learn how Cody's local indexing engine works to provide fast keyword search in your workspace.</p>
+
+Cody uses **symf** (symbol finder), a local keyword search engine, to create and maintain code indexes for your workspace folders. This enables fast context retrieval directly from your local codebase.
+
+## How Local Indexing Works
+
+Symf automatically creates and maintains indexes of your code:
+
+- Starts automatically when you open a workspace and authenticate
+- Runs in the background with minimal performance impact
+- Detects file changes and reindexes as needed
+- Persists across restarts for instant availability
+
+## Configuration Settings
+
+### VS Code Settings
+
+Configure symf behavior through VS Code settings (`settings.json`):
+
+**`cody.experimental.symf.enabled`** (default: `true`)
+- Enables or disables symf functionality
+- Set to `false` to completely disable local indexing
+
+**`cody.internal.symf.path`**
+- Specify a custom path to the symf binary
+- When set, automatic download is skipped
+- Useful for custom builds or air-gapped environments
+
+**Manual Index Control:**
+
+Use the Command Palette to manually trigger indexing:
+
+- **`Cody: Update search index for current workspace folder`** - Reindex the active workspace folder
+- **`Cody: Update search index for all workspace folders`** - Reindex all open workspace folders
+
+### JetBrains Settings
+
+Configure symf behavior in your project's custom settings file:
+
+**Location:** `.idea/.sourcegraph/cody_settings.json`
+
+**`cody.experimental.symf.enabled`** (default: `true`)
+```json
+{
+  "cody.experimental.symf.enabled": "true"
+}
+```
+
+**Note:** JetBrains does not currently expose manual index control commands. Indexing happens automatically in the background through the Cody Agent.
+
+### Enterprise Configuration
+
+Administrators can use the **`symf-retrieval-disabled`** feature flag to completely disable symf for their organization. This:
+
+- Prevents automatic binary downloads
+- Disables all symf operations
+- Useful for organizations with strict firewall policies
+- Works for both VS Code and JetBrains clients
+
+## Index Storage Location
+
+Indexes are stored in your VS Code extension's global storage directory under `symf/indexroot/`. The exact location varies by operating system:
+
+### Windows
+```
+%APPDATA%\Code\User\globalStorage\sourcegraph.cody-ai\symf\indexroot\
+```
+
+### macOS
+```
+~/Library/Application Support/Code/User/globalStorage/sourcegraph.cody-ai/symf/indexroot/
+```
+
+### Linux
+```
+~/.config/Code/User/globalStorage/sourcegraph.cody-ai/symf/indexroot/
+```
+
+Each workspace folder gets its own subdirectory based on its absolute path. The symf binary itself is stored in the parent `symf/` directory.
+
+### Additional Storage Directories
+
+- **`.tmp/`** - Temporary indexes during rebuilding
+- **`.trash/`** - Deleted indexes
+- **`.failed/`** - Tracks failed index attempts to prevent retry loops
+
+## Limitations
+
+- **Desktop only** - Only works on VS Code Desktop with local file systems (file:// URIs)
+- **Not supported** on VS Code Web, remote workspaces, or virtual file systems
+- **Authentication required** - Indexing only starts after you authenticate with Cody
+- **Retry logic** - If indexing fails, it won't automatically retry unless you manually trigger a reindex
+
+### Network Requirements
+
+The symf binary is automatically downloaded from GitHub (`https://github.com/sourcegraph/symf/releases/`). Organizations with firewall restrictions should either:
+
+1. Allow downloads from GitHub releases
+2. Use the `cody.internal.symf.path` setting to point to a manually installed binary
+3. Enable the `symf-retrieval-disabled` feature flag to disable symf entirely
+
+## Troubleshooting
+
+If you experience issues with local indexing:
+
+1. **Check the Cody output channel** for debug logs (View → Output → Cody)
+2. **Manually trigger reindexing** using the Command Palette commands
+3. **Clear indexes** by deleting the storage directory and restarting VS Code
+4. **Use a custom binary** if automatic downloads fail due to network restrictions
+5. **Verify authentication** - Ensure you're signed in to Cody
+
+For persistent issues, consider disabling symf with `cody.experimental.symf.enabled: false` and relying on other context retrieval methods.