diff --git a/inc/Abilities/WorkspaceAbilities.php b/inc/Abilities/WorkspaceAbilities.php
index 2deece2..9cd3e97 100644
--- a/inc/Abilities/WorkspaceAbilities.php
+++ b/inc/Abilities/WorkspaceAbilities.php
@@ -113,8 +113,8 @@ private function registerAbilities(): void {
 							),
 							'type' => array(
 								'type'        => 'string',
-								'enum'        => array( 'primary', 'worktree' ),
-								'description' => 'Optional checkout type filter. Use "primary" for base checkouts or "worktree" for branch worktrees.',
+								'enum'        => array( 'primary', 'worktree', 'context' ),
+								'description' => 'Optional checkout type filter. Use "primary" for base checkouts, "worktree" for branch worktrees, or "context" for read-only context repositories.',
 							),
 						),
 					),
diff --git a/inc/Tools/WorkspaceTools.php b/inc/Tools/WorkspaceTools.php
index fb9fe7e..31bf15c 100644
--- a/inc/Tools/WorkspaceTools.php
+++ b/inc/Tools/WorkspaceTools.php
@@ -1035,8 +1035,8 @@ public function getListDefinition(): array
                     ),
                     'type' => array(
                         'type'        => 'string',
-                        'enum'        => array( 'primary', 'worktree' ),
-                        'description' => 'Optional checkout type filter. Use "primary" for base checkouts or "worktree" for branch worktrees.',
+                        'enum'        => array( 'primary', 'worktree', 'context' ),
+                        'description' => 'Optional checkout type filter. Use "primary" for base checkouts, "worktree" for branch worktrees, or "context" for read-only context repositories.',
                     ),
             ),
             'required'   => array(),
diff --git a/inc/Workspace/RemoteWorkspaceBackend.php b/inc/Workspace/RemoteWorkspaceBackend.php
index 7bdc025..f966e1e 100644
--- a/inc/Workspace/RemoteWorkspaceBackend.php
+++ b/inc/Workspace/RemoteWorkspaceBackend.php
@@ -198,6 +198,11 @@ public function worktree_prune(): array {
 	 * @return array<string,mixed>|\WP_Error
 	 */
 	public function read_file( string $handle, string $path, int $max_size, ?int $offset = null, ?int $limit = null ): array|\WP_Error {
+		$policy_error = WorkspaceAliasResolver::read_error_if_disallowed($handle, $path);
+		if ( null !== $policy_error ) {
+			return $policy_error;
+		}
+
 		$context = $this->resolve_handle($handle);
 		if ( is_wp_error($context) ) {
 			return $context;
@@ -234,13 +239,18 @@ public function read_file( string $handle, string $path, int $max_size, ?int $of
 			$result_content = implode("\n", $lines);
 		}
 
-		return array(
+		$result = array(
 			'success' => true,
 			'backend' => 'github_api',
 			'content' => $result_content,
 			'path'    => $path,
 			'size'    => $size,
 		);
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($handle);
+		}
+
+		return $result;
 	}
 
 	/**
@@ -249,6 +259,11 @@ public function read_file( string $handle, string $path, int $max_size, ?int $of
 	 * @return array<string,mixed>|\WP_Error
 	 */
 	public function list_directory( string $handle, ?string $path = null ): array|\WP_Error {
+		$policy_error = WorkspaceAliasResolver::read_error_if_disallowed($handle, $path ?? '');
+		if ( null !== $policy_error ) {
+			return $policy_error;
+		}
+
 		$context = $this->resolve_handle($handle);
 		if ( is_wp_error($context) ) {
 			return $context;
@@ -287,13 +302,20 @@ public function list_directory( string $handle, ?string $path = null ): array|\W
 			);
 		}
 
-		return array(
+		$entries = WorkspaceAliasResolver::filter_context_entries($handle, '' === $prefix ? '/' : $prefix, $entries);
+
+		$result = array(
 			'success' => true,
 			'backend' => 'github_api',
 			'repo'    => $handle,
 			'path'    => '' === $prefix ? '/' : $prefix,
 			'entries' => $entries,
 		);
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($handle);
+		}
+
+		return $result;
 	}
 
 	/**
@@ -302,6 +324,11 @@ public function list_directory( string $handle, ?string $path = null ): array|\W
 	 * @return array<string,mixed>|\WP_Error
 	 */
 	public function grep( string $handle, string $pattern, ?string $path = null, ?string $include_pattern = null, int $max_results = 100, int $context_lines = 0 ): array|\WP_Error {
+		$policy_error = WorkspaceAliasResolver::read_error_if_disallowed($handle, $path ?? '');
+		if ( null !== $policy_error ) {
+			return $policy_error;
+		}
+
 		$context = $this->resolve_handle($handle);
 		if ( is_wp_error($context) ) {
 			return $context;
@@ -353,7 +380,11 @@ public function grep( string $handle, string $pattern, ?string $path = null, ?st
 		}
 
 		foreach ( $files as $file ) {
-			$file_path = (string) ( $file['path'] ?? '' );
+			$file_path      = (string) ( $file['path'] ?? '' );
+			$context_policy = WorkspaceAliasResolver::context_policy_for($handle);
+			if ( null !== $context_policy && ! WorkspaceAliasResolver::path_allowed_by_policy($file_path, $context_policy) ) {
+				continue;
+			}
 			if ( '' === $file_path || isset($seen[ $file_path ]) || ! $this->path_matches_include($file_path, $include_pattern) ) {
 				continue;
 			}
@@ -380,7 +411,7 @@ public function grep( string $handle, string $pattern, ?string $path = null, ?st
 			}
 		}
 
-		return array(
+		$result = array(
 			'success'   => true,
 			'backend'   => 'github_api',
 			'repo'      => $handle,
@@ -390,6 +421,11 @@ public function grep( string $handle, string $pattern, ?string $path = null, ?st
 			'count'     => count($matches),
 			'truncated' => count($matches) >= $max_results,
 		);
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($handle);
+		}
+
+		return $result;
 	}
 
 	/**
@@ -398,6 +434,10 @@ public function grep( string $handle, string $pattern, ?string $path = null, ?st
 	 * @return array<string,mixed>|\WP_Error
 	 */
 	public function write_file( string $handle, string $path, string $content ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'write');
+		}
+
 		$context = $this->resolve_handle($handle);
 		if ( is_wp_error($context) ) {
 			return $context;
@@ -428,6 +468,10 @@ public function write_file( string $handle, string $path, string $content ): arr
 	 * @return array<string,mixed>|\WP_Error
 	 */
 	public function edit_file( string $handle, string $path, string $old_string, string $new_string, bool $replace_all = false ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'edit');
+		}
+
 		$context = $this->resolve_handle($handle);
 		if ( is_wp_error($context) ) {
 			return $context;
@@ -490,12 +534,13 @@ public function show( string $handle ): array|\WP_Error {
 
 		$files = array_values(array_unique(array_values( (array) $context['changed_files'])));
 
-		return array(
+		$result = array(
 			'success'     => true,
 			'backend'     => 'github_api',
 			'name'        => $handle,
 			'repo'        => $context['repo_name'],
-			'is_worktree' => isset($context['branch']) && '' !== (string) $context['branch'],
+			'is_worktree' => empty($context['read_only_context']) && isset($context['branch']) && '' !== (string) $context['branch'],
+			'is_context'  => ! empty($context['read_only_context']),
 			'path'        => 'github://' . $context['repo'] . ( '' !== (string) $context['branch']
 			? '#' . $context['branch']
 			: '' ),
@@ -505,6 +550,11 @@ public function show( string $handle ): array|\WP_Error {
 			'dirty'       => count($files),
 			'files'       => $files,
 		);
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($handle);
+		}
+
+		return $result;
 	}
 
 	/**
@@ -514,6 +564,10 @@ public function show( string $handle ): array|\WP_Error {
 	 */
 	public function git_diff( string $handle, ?string $from = null, ?string $to = null, bool $staged = false, ?string $path = null ): array|\WP_Error {
 		unset($staged);
+		$policy_error = WorkspaceAliasResolver::read_error_if_disallowed($handle, $path ?? '');
+		if ( null !== $policy_error ) {
+			return $policy_error;
+		}
 
 		$context = $this->resolve_handle($handle);
 		if ( is_wp_error($context) ) {
@@ -549,13 +603,18 @@ public function git_diff( string $handle, ?string $from = null, ?string $to = nu
 			$diff .= $this->build_unified_file_diff($changed_path, $old_content, (string) $new_content);
 		}
 
-		return array(
+		$result = array(
 			'success' => true,
 			'backend' => 'github_api',
 			'name'    => $handle,
 			'repo'    => $context['repo_name'],
 			'diff'    => $diff,
 		);
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($handle);
+		}
+
+		return $result;
 	}
 
 	/**
@@ -569,13 +628,14 @@ public function git_status( string $handle ): array|\WP_Error {
 			return $context;
 		}
 
-		$files = array_values(array_unique(array_values( (array) $context['changed_files'])));
-		return array(
+		$files  = array_values(array_unique(array_values( (array) $context['changed_files'])));
+		$result = array(
 			'success'     => true,
 			'backend'     => 'github_api',
 			'name'        => $handle,
 			'repo'        => $context['repo_name'],
-			'is_worktree' => true,
+			'is_worktree' => empty($context['read_only_context']),
+			'is_context'  => ! empty($context['read_only_context']),
 			'path'        => 'github://' . $context['repo'] . '#' . $context['branch'],
 			'branch'      => $context['branch'],
 			'remote'      => 'https://github.com/' . $context['repo'] . '.git',
@@ -583,6 +643,11 @@ public function git_status( string $handle ): array|\WP_Error {
 			'dirty'       => count($files),
 			'files'       => $files,
 		);
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($handle);
+		}
+
+		return $result;
 	}
 
 	/**
@@ -591,6 +656,10 @@ public function git_status( string $handle ): array|\WP_Error {
 	 * @return array<string,mixed>|\WP_Error
 	 */
 	public function git_add( string $handle, array $paths ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'git add');
+		}
+
 		$context = $this->resolve_handle($handle);
 		if ( is_wp_error($context) ) {
 			return $context;
@@ -611,6 +680,10 @@ public function git_add( string $handle, array $paths ): array|\WP_Error {
 	 * @return array<string,mixed>|\WP_Error
 	 */
 	public function git_commit( string $handle, string $message ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'git commit');
+		}
+
 		$context = $this->resolve_handle($handle);
 		if ( is_wp_error($context) ) {
 			return $context;
@@ -1103,6 +1176,10 @@ private function group_diff_hunks( array $ops, int $context_lines ): array {
 	 * @return array<string,mixed>|\WP_Error
 	 */
 	public function git_push( string $handle, string $remote = 'origin', ?string $branch = null ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'git push');
+		}
+
 		$context = $this->resolve_handle($handle);
 		if ( is_wp_error($context) ) {
 			return $context;
@@ -1131,6 +1208,26 @@ public function git_push( string $handle, string $remote = 'origin', ?string $br
 	 * @return array<string,mixed>
 	 */
 	private function resolve_handle( string $handle ): array|\WP_Error {
+		$context_policy = WorkspaceAliasResolver::context_policy_for($handle);
+		if ( null !== $context_policy ) {
+			$repo = (string) ( $context_policy['repo'] ?? '' );
+			if ( '' === $repo ) {
+				$repo = (string) ( $context_policy['target'] ?? $handle );
+			}
+
+			return array(
+				'handle'            => (string) $context_policy['alias'],
+				'repo_name'         => (string) $context_policy['alias'],
+				'repo'              => $repo,
+				'branch'            => (string) ( $context_policy['ref'] ?? '' ),
+				'read_ref'          => (string) ( $context_policy['ref'] ?? '' ),
+				'pending_files'     => array(),
+				'changed_files'     => array(),
+				'last_commit_sha'   => '',
+				'read_only_context' => true,
+			);
+		}
+
 		$handle = $this->resolve_alias($handle);
 		$state  = $this->state();
 		if ( isset($state['worktrees'][ $handle ]) ) {
diff --git a/inc/Workspace/WorkspaceAliasResolver.php b/inc/Workspace/WorkspaceAliasResolver.php
index ea7dc30..190a52b 100644
--- a/inc/Workspace/WorkspaceAliasResolver.php
+++ b/inc/Workspace/WorkspaceAliasResolver.php
@@ -13,7 +13,8 @@ class WorkspaceAliasResolver {
 
 
 
-	private const OPTION = 'datamachine_code_workspace_aliases';
+	private const OPTION         = 'datamachine_code_workspace_aliases';
+	private const CONTEXT_OPTION = 'datamachine_code_context_repositories';
 
 	/**
 	 * Return normalized alias specs keyed by agent-facing alias.
@@ -21,7 +22,7 @@ class WorkspaceAliasResolver {
 	 * Runners can persist aliases in the option, or inject them just-in-time via
 	 * the filter when a single conversation should see an opaque project name.
 	 *
-	 * @return array<string,array{target:string,root:string}>
+	 * @return array<string,array{target:string,root:string,access:string,is_context:bool,repo:string,ref:string,paths:array<int,string>}>
 	 */
 	public static function aliases(): array {
 		$aliases = function_exists('get_option') ? get_option(self::OPTION, array()) : array();
@@ -33,6 +34,17 @@ public static function aliases(): array {
 			$aliases = apply_filters('datamachine_code_workspace_aliases', $aliases);
 		}
 
+		foreach ( self::context_repositories() as $alias => $context ) {
+			$aliases[ $alias ] = array_merge(
+				$context,
+				array(
+					'target'     => (string) ( $context['target'] ?? $alias ),
+					'access'     => 'read_only',
+					'is_context' => true,
+				)
+			);
+		}
+
 		$normalized = array();
 		foreach ( $aliases as $alias => $spec ) {
 			$alias = trim( (string) $alias);
@@ -48,8 +60,13 @@ public static function aliases(): array {
 				continue;
 			}
 			$normalized[ $alias ] = array(
-				'target' => $handle,
-				'root'   => $root,
+				'target'     => $handle,
+				'root'       => $root,
+				'access'     => is_array($spec) ? (string) ( $spec['access'] ?? 'read_write' ) : 'read_write',
+				'is_context' => is_array($spec) && ! empty($spec['is_context']),
+				'repo'       => is_array($spec) ? (string) ( $spec['repo'] ?? '' ) : '',
+				'ref'        => is_array($spec) ? (string) ( $spec['ref'] ?? '' ) : '',
+				'paths'      => is_array($spec) ? self::normalize_paths($spec['paths'] ?? array()) : array(),
 			);
 		}
 
@@ -64,7 +81,7 @@ public static function resolve( string $handle ): string {
 	/**
 	 * Return the normalized alias spec for an agent-facing handle.
 	 *
-	 * @return array{target:string,root:string}|null
+	 * @return array{target:string,root:string,access:string,is_context:bool,repo:string,ref:string,paths:array<int,string>}|null
 	 */
 	public static function spec( string $handle ): ?array {
 		return self::aliases()[ $handle ] ?? null;
@@ -88,6 +105,177 @@ public static function root_for( string $handle ): string {
 		return self::aliases()[ $handle ]['root'] ?? '';
 	}
 
+	/**
+	 * Return normalized read-only context repository specs keyed by alias.
+	 *
+	 * Runners can persist the list in `datamachine_code_context_repositories` or
+	 * inject it per run via the `datamachine_code_context_repositories` filter.
+	 *
+	 * @return array<string,array<string,mixed>>
+	 */
+	public static function context_repositories(): array {
+		$contexts = function_exists('get_option') ? get_option(self::CONTEXT_OPTION, array()) : array();
+		if ( ! is_array($contexts) ) {
+			$contexts = array();
+		}
+
+		if ( function_exists('apply_filters') ) {
+			$contexts = apply_filters('datamachine_code_context_repositories', $contexts);
+		}
+
+		$normalized = array();
+		foreach ( $contexts as $key => $spec ) {
+			if ( ! is_array($spec) ) {
+				continue;
+			}
+
+			$alias = trim( (string) ( $spec['alias'] ?? $key ));
+			if ( '' === $alias ) {
+				continue;
+			}
+
+			$repo   = trim( (string) ( $spec['repo'] ?? '' ));
+			$target = trim( (string) ( $spec['target'] ?? $spec['handle'] ?? $spec['name'] ?? $alias ));
+			$root   = self::normalize_root( (string) ( $spec['root'] ?? $spec['agent_root'] ?? $spec['path_prefix'] ?? '' ));
+			$paths  = self::normalize_paths($spec['paths'] ?? array());
+
+			$normalized[ $alias ] = array(
+				'alias'  => $alias,
+				'repo'   => $repo,
+				'ref'    => trim( (string) ( $spec['ref'] ?? '' )),
+				'target' => $target,
+				'root'   => $root,
+				'paths'  => $paths,
+			);
+		}
+
+		return $normalized;
+	}
+
+	/**
+	 * Return context policy for either the alias or its resolved target handle.
+	 *
+	 * @return array<string,mixed>|null
+	 */
+	public static function context_policy_for( string $handle ): ?array {
+		foreach ( self::aliases() as $alias => $spec ) {
+			if ( empty($spec['is_context']) ) {
+				continue;
+			}
+
+			if ( $handle === $alias || $handle === (string) $spec['target'] ) {
+				return array_merge($spec, array( 'alias' => $alias ));
+			}
+		}
+
+		return null;
+	}
+
+	public static function is_context_repository( string $handle ): bool {
+		return null !== self::context_policy_for($handle);
+	}
+
+	public static function mutation_error( string $handle, string $operation = 'mutation' ): \WP_Error {
+		$policy = self::context_policy_for($handle);
+		$alias  = (string) ( $policy['alias'] ?? $handle );
+
+		return new \WP_Error(
+			'context_repository_read_only',
+			sprintf(
+				'Context repository "%s" is read-only for this run; %s operations must target the writable workspace repository instead.',
+				$alias,
+				$operation
+			),
+			array(
+				'status'           => 403,
+				'workspace_policy' => self::policy_attestation($handle),
+			)
+		);
+	}
+
+	public static function read_error_if_disallowed( string $handle, ?string $path ): ?\WP_Error {
+		$policy = self::context_policy_for($handle);
+		if ( null === $policy ) {
+			return null;
+		}
+
+		$normalized_path = self::normalize_path( (string) ( $path ?? '' ) );
+		if ( self::path_allowed_by_policy($normalized_path, $policy, true) ) {
+			return null;
+		}
+
+		return new \WP_Error(
+			'context_repository_path_not_allowed',
+			sprintf('Path "%s" is outside the read allowlist for context repository "%s".', '' === $normalized_path ? '/' : $normalized_path, (string) $policy['alias']),
+			array(
+				'status'           => 403,
+				'workspace_policy' => self::policy_attestation($handle),
+			)
+		);
+	}
+
+	public static function filter_context_entries( string $handle, string $listed_path, array $entries ): array {
+		$policy = self::context_policy_for($handle);
+		if ( null === $policy || empty($policy['paths']) ) {
+			return $entries;
+		}
+
+		$base = self::normalize_path($listed_path);
+		return array_values(
+			array_filter(
+				$entries,
+				static function ( array $entry ) use ( $base, $policy ): bool {
+					$name = (string) ( $entry['name'] ?? '' );
+					$path = '' === $base || '/' === $base ? $name : $base . '/' . $name;
+					return self::path_allowed_by_policy($path, $policy, true);
+				}
+			)
+		);
+	}
+
+	public static function policy_attestation( string $handle ): array {
+		$policy = self::context_policy_for($handle);
+		if ( null === $policy ) {
+			return array(
+				'access'    => 'read_write',
+				'writable'  => true,
+				'read_only' => false,
+			);
+		}
+
+		$attestation = array(
+			'access'        => 'read_only',
+			'writable'      => false,
+			'read_only'     => true,
+			'alias'         => (string) $policy['alias'],
+			'target'        => (string) $policy['target'],
+			'repo'          => (string) ( $policy['repo'] ?? '' ),
+			'ref'           => (string) ( $policy['ref'] ?? '' ),
+			'allowed_paths' => array_values( (array) ( $policy['paths'] ?? array() ) ),
+		);
+
+		$policy_json                = function_exists('wp_json_encode') ? wp_json_encode($attestation) : http_build_query($attestation, '', '&', PHP_QUERY_RFC3986);
+		$attestation['policy_hash'] = hash('sha256', (string) $policy_json);
+
+		return $attestation;
+	}
+
+	public static function path_allowed_by_policy( string $path, array $policy, bool $allow_ancestors = false ): bool {
+		$paths = self::normalize_paths($policy['paths'] ?? array());
+		if ( empty($paths) ) {
+			return true;
+		}
+
+		$path = self::normalize_path($path);
+		foreach ( $paths as $allowed ) {
+			if ( self::path_matches($path, $allowed, $allow_ancestors) ) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
 	public static function scope_path( string $path, string $root ): string|false {
 		$root = self::normalize_root($root);
 		if ( '' === $root ) {
@@ -182,6 +370,64 @@ private static function normalize_root( string $root ): string {
 		return implode('/', $segments);
 	}
 
+	private static function normalize_paths( mixed $paths ): array {
+		if ( ! is_array($paths) ) {
+			return array();
+		}
+
+		$normalized = array();
+		foreach ( $paths as $path ) {
+			$path = self::normalize_path( (string) $path );
+			if ( '' !== $path ) {
+				$normalized[] = $path;
+			}
+		}
+
+		return array_values(array_unique($normalized));
+	}
+
+	private static function normalize_path( string $path ): string {
+		$path     = trim(str_replace('\\', '/', $path), '/');
+		$segments = array();
+		foreach ( explode('/', $path) as $segment ) {
+			if ( '' === $segment || '.' === $segment || '..' === $segment || str_contains($segment, "\0") ) {
+				continue;
+			}
+			$segments[] = $segment;
+		}
+
+		return implode('/', $segments);
+	}
+
+	private static function path_matches( string $path, string $allowed, bool $allow_ancestors ): bool {
+		$path    = self::normalize_path($path);
+		$allowed = self::normalize_path($allowed);
+		if ( '' === $allowed ) {
+			return true;
+		}
+
+		if ( $path === $allowed || fnmatch($allowed, $path) ) {
+			return true;
+		}
+
+		if ( str_ends_with($allowed, '/**') ) {
+			$prefix = substr($allowed, 0, -3);
+			if ( $path === $prefix || str_starts_with($path, $prefix . '/') ) {
+				return true;
+			}
+		}
+
+		if ( $allow_ancestors && '' === $path ) {
+			return true;
+		}
+
+		if ( $allow_ancestors ) {
+			return str_starts_with($allowed, $path . '/');
+		}
+
+		return false;
+	}
+
 	private static function sanitize_scoped_string( string $value, string $root ): string {
 		$root = self::normalize_root($root);
 		if ( '' === $root ) {
diff --git a/inc/Workspace/WorkspaceGitOperations.php b/inc/Workspace/WorkspaceGitOperations.php
index 0463b54..1577940 100644
--- a/inc/Workspace/WorkspaceGitOperations.php
+++ b/inc/Workspace/WorkspaceGitOperations.php
@@ -62,6 +62,9 @@ public function git_status( string $handle ): array|\WP_Error {
 		if ( null !== $policy_attestation ) {
 			$response['workspace_policy'] = $policy_attestation;
 		}
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			$response['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($handle);
+		}
 
 		return $response;
 	}
@@ -74,6 +77,10 @@ public function git_status( string $handle ): array|\WP_Error {
 	 * @return array
 	 */
 	public function git_pull( string $handle, bool $allow_dirty = false, bool $allow_primary_mutation = false ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'git pull');
+		}
+
 		$parsed    = $this->parse_handle($handle);
 		$repo_path = $this->resolve_repo_path($handle);
 		if ( is_wp_error($repo_path) ) {
@@ -120,6 +127,10 @@ public function git_pull( string $handle, bool $allow_dirty = false, bool $allow
 	 * @return array
 	 */
 	public function git_add( string $handle, array $paths, bool $allow_primary_mutation = false ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'git add');
+		}
+
 		$parsed    = $this->parse_handle($handle);
 		$repo_name = $parsed['repo'];
 		$repo_path = $this->resolve_repo_path($handle);
@@ -217,6 +228,10 @@ public function git_add( string $handle, array $paths, bool $allow_primary_mutat
 	 * @return array{success: bool, name: string, repo: string, path: string, deleted: array<int,string>, was_tracked: bool}|\WP_Error
 	 */
 	public function delete_path( string $handle, string $path, bool $recursive = false, bool $allow_primary_mutation = false ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'delete');
+		}
+
 		$parsed    = $this->parse_handle($handle);
 		$repo_name = $parsed['repo'];
 		$repo_path = $this->resolve_repo_path($handle);
@@ -360,6 +375,10 @@ private function remove_directory_recursive( string $absolute, string $repo_path
 	 * @return array
 	 */
 	public function git_commit( string $handle, string $message, bool $allow_primary_mutation = false ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'git commit');
+		}
+
 		$parsed    = $this->parse_handle($handle);
 		$repo_name = $parsed['repo'];
 		$repo_path = $this->resolve_repo_path($handle);
@@ -438,6 +457,10 @@ public function git_commit( string $handle, string $message, bool $allow_primary
 	 * @return array
 	 */
 	public function git_push( string $handle, string $remote = 'origin', ?string $branch = null, bool $allow_primary_mutation = false, bool $force_with_lease = false, ?string $expected_sha = null ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'git push');
+		}
+
 		$parsed    = $this->parse_handle($handle);
 		$repo_name = $parsed['repo'];
 		$repo_path = $this->resolve_repo_path($handle);
@@ -557,6 +580,10 @@ public function git_push( string $handle, string $remote = 'origin', ?string $br
 	 * @return array<string,mixed>|\WP_Error
 	 */
 	public function git_rebase( string $handle, ?string $onto = null, ?string $strategy_option = null, bool $continue_rebase = false, bool $allow_primary_mutation = false ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'git rebase');
+		}
+
 		$parsed    = $this->parse_handle($handle);
 		$repo_name = $parsed['repo'];
 		$repo_path = $this->resolve_repo_path($handle);
@@ -627,6 +654,10 @@ public function git_rebase( string $handle, ?string $onto = null, ?string $strat
 	 * @return array<string,mixed>|\WP_Error
 	 */
 	public function git_reset( string $handle, string $mode = 'mixed', ?string $target = null, bool $allow_destructive = false, bool $allow_primary_mutation = false ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($handle) ) {
+			return WorkspaceAliasResolver::mutation_error($handle, 'git reset');
+		}
+
 		$parsed    = $this->parse_handle($handle);
 		$repo_name = $parsed['repo'];
 		$repo_path = $this->resolve_repo_path($handle);
@@ -890,12 +921,17 @@ public function git_log( string $name, int $limit = 20 ): array|\WP_Error {
 		}
 
 		$parsed = $this->parse_handle($name);
-		return array(
+		$result = array(
 			'success' => true,
 			'name'    => $parsed['dir_name'],
 			'repo'    => $parsed['repo'],
 			'entries' => $entries,
 		);
+		if ( WorkspaceAliasResolver::is_context_repository($name) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($name);
+		}
+
+		return $result;
 	}
 
 	/**
@@ -909,6 +945,11 @@ public function git_log( string $name, int $limit = 20 ): array|\WP_Error {
 	 * @return array
 	 */
 	public function git_diff( string $name, ?string $from = null, ?string $to = null, bool $staged = false, ?string $path = null ): array|\WP_Error {
+		$policy_error = WorkspaceAliasResolver::read_error_if_disallowed($name, $path ?? '');
+		if ( null !== $policy_error ) {
+			return $policy_error;
+		}
+
 		$repo_path = $this->resolve_repo_path($name);
 		if ( is_wp_error($repo_path) ) {
 			return $repo_path;
@@ -943,12 +984,17 @@ public function git_diff( string $name, ?string $from = null, ?string $to = null
 		}
 
 		$parsed = $this->parse_handle($name);
-		return array(
+		$result = array(
 			'success' => true,
 			'name'    => $parsed['dir_name'],
 			'repo'    => $parsed['repo'],
 			'diff'    => $diff['output'] ?? '',
 		);
+		if ( WorkspaceAliasResolver::is_context_repository($name) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($name);
+		}
+
+		return $result;
 	}
 
 	/**
diff --git a/inc/Workspace/WorkspaceReader.php b/inc/Workspace/WorkspaceReader.php
index 2b9b37f..a454588 100644
--- a/inc/Workspace/WorkspaceReader.php
+++ b/inc/Workspace/WorkspaceReader.php
@@ -40,6 +40,11 @@ public function __construct( Workspace $workspace ) {
 	 * @return array{success: bool, content?: string, path?: string, size?: int, lines_read?: int, offset?: int}|\WP_Error
 	 */
 	public function read_file( string $name, string $path, int $max_size = Workspace::MAX_READ_SIZE, ?int $offset = null, ?int $limit = null ): array|\WP_Error {
+		$policy_error = WorkspaceAliasResolver::read_error_if_disallowed($name, $path);
+		if ( null !== $policy_error ) {
+			return $policy_error;
+		}
+
 		$repo_path = $this->workspace->get_repo_path($name);
 		$path      = ltrim($path, '/');
 
@@ -51,10 +56,10 @@ public function read_file( string $name, string $path, int $max_size = Workspace
 		$validation = $this->workspace->validate_containment($file_path, $repo_path);
 
 		if ( ! $validation['valid'] ) {
-			return new \WP_Error('path_traversal', $validation['message'], array( 'status' => 403 ));
+			return new \WP_Error('path_traversal', (string) ( $validation['message'] ?? 'Path traversal detected. Access denied.' ), array( 'status' => 403 ));
 		}
 
-		$real_path = $validation['real_path'];
+		$real_path = (string) ( $validation['real_path'] ?? '' );
 
 		if ( ! is_file($real_path) ) {
 			return new \WP_Error('file_not_found', sprintf('File not found: %s', $path), array( 'status' => 404 ));
@@ -65,6 +70,9 @@ public function read_file( string $name, string $path, int $max_size = Workspace
 		}
 
 		$size = filesize($real_path);
+		if ( false === $size ) {
+			return new \WP_Error('file_size_failed', sprintf('Failed to determine file size: %s', $path), array( 'status' => 500 ));
+		}
 
 		if ( $size > $max_size ) {
 			return new \WP_Error(
@@ -117,6 +125,10 @@ public function read_file( string $name, string $path, int $max_size = Workspace
 			'size'    => $size,
 		);
 
+		if ( WorkspaceAliasResolver::is_context_repository($name) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($name);
+		}
+
 		if ( null !== $offset || null !== $limit ) {
 			$result['lines_read'] = $lines_read;
 			$result['offset']     = $start_line;
@@ -133,6 +145,11 @@ public function read_file( string $name, string $path, int $max_size = Workspace
 	 * @return array{success: bool, repo?: string, path?: string, entries?: array}|\WP_Error
 	 */
 	public function list_directory( string $name, ?string $path = null ): array|\WP_Error {
+		$policy_error = WorkspaceAliasResolver::read_error_if_disallowed($name, $path ?? '');
+		if ( null !== $policy_error ) {
+			return $policy_error;
+		}
+
 		$repo_path = $this->workspace->get_repo_path($name);
 
 		if ( ! is_dir($repo_path) ) {
@@ -148,10 +165,10 @@ public function list_directory( string $name, ?string $path = null ): array|\WP_
 			$validation = $this->workspace->validate_containment($target_path, $repo_path);
 
 			if ( ! $validation['valid'] ) {
-				return new \WP_Error('path_traversal', $validation['message'], array( 'status' => 403 ));
+				return new \WP_Error('path_traversal', (string) ( $validation['message'] ?? 'Path traversal detected. Access denied.' ), array( 'status' => 403 ));
 			}
 
-			$target_path = $validation['real_path'];
+			$target_path = (string) ( $validation['real_path'] ?? '' );
 		}
 
 		if ( ! is_dir($target_path) ) {
@@ -195,12 +212,20 @@ function ( $a, $b ) {
 			}
 		);
 
-		return array(
+		$items = WorkspaceAliasResolver::filter_context_entries($name, $path ?? '/', $items);
+
+		$result = array(
 			'success' => true,
 			'repo'    => $name,
 			'path'    => $path ?? '/',
 			'entries' => $items,
 		);
+
+		if ( WorkspaceAliasResolver::is_context_repository($name) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($name);
+		}
+
+		return $result;
 	}
 
 	/**
@@ -215,6 +240,11 @@ function ( $a, $b ) {
 	 * @return array{success: bool, repo?: string, path?: string, pattern?: string, matches?: array, count?: int, truncated?: bool}|\WP_Error
 	 */
 	public function grep( string $name, string $pattern, ?string $path = null, ?string $include_pattern = null, int $max_results = 100, int $context_lines = 0 ): array|\WP_Error {
+		$policy_error = WorkspaceAliasResolver::read_error_if_disallowed($name, $path ?? '');
+		if ( null !== $policy_error ) {
+			return $policy_error;
+		}
+
 		$repo_path = $this->workspace->get_repo_path($name);
 		if ( ! is_dir($repo_path) ) {
 			return new \WP_Error('repo_not_found', sprintf('Repository "%s" not found in workspace.', $name), array( 'status' => 404 ));
@@ -232,9 +262,9 @@ public function grep( string $name, string $pattern, ?string $path = null, ?stri
 			$target_path = $repo_real . '/' . $path;
 			$validation  = $this->workspace->validate_containment($target_path, $repo_real);
 			if ( ! $validation['valid'] ) {
-				return new \WP_Error('path_traversal', $validation['message'], array( 'status' => 403 ));
+				return new \WP_Error('path_traversal', (string) ( $validation['message'] ?? 'Path traversal detected. Access denied.' ), array( 'status' => 403 ));
 			}
-			$target_path = $validation['real_path'];
+			$target_path = (string) ( $validation['real_path'] ?? '' );
 			$search_path = $path;
 		}
 
@@ -253,7 +283,11 @@ public function grep( string $name, string $pattern, ?string $path = null, ?stri
 		$files         = is_file($target_path) ? array( $target_path ) : $this->iterable_files($target_path);
 
 		foreach ( $files as $file_path ) {
-			$relative_path = ltrim(substr($file_path, strlen($repo_real)), '/');
+			$relative_path  = ltrim(substr($file_path, strlen($repo_real)), '/');
+			$context_policy = WorkspaceAliasResolver::context_policy_for($name);
+			if ( null !== $context_policy && ! WorkspaceAliasResolver::path_allowed_by_policy($relative_path, $context_policy) ) {
+				continue;
+			}
 			if ( str_starts_with($relative_path, '.git/') || ! $this->path_matches_include($relative_path, $include_pattern) ) {
 				continue;
 			}
@@ -269,7 +303,7 @@ public function grep( string $name, string $pattern, ?string $path = null, ?stri
 			}
 		}
 
-		return array(
+		$result = array(
 			'success'   => true,
 			'repo'      => $name,
 			'path'      => $search_path,
@@ -278,6 +312,12 @@ public function grep( string $name, string $pattern, ?string $path = null, ?stri
 			'count'     => count($matches),
 			'truncated' => count($matches) >= $max_results,
 		);
+
+		if ( WorkspaceAliasResolver::is_context_repository($name) ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($name);
+		}
+
+		return $result;
 	}
 
 	private function compile_search_pattern( string $pattern ): string|\WP_Error {
@@ -331,6 +371,10 @@ private function path_matches_include( string $path, ?string $include_pattern ):
 	 * @return array<int,array<string,mixed>>|\WP_Error
 	 */
 	private function grep_file( string $repo, string $file_path, string $relative_path, string $regex, int $context_lines, int $limit ): array|\WP_Error {
+		if ( $limit < 1 ) {
+			return new \WP_Error('grep_limit_exhausted', 'Search result limit exhausted.', array( 'status' => 400 ));
+		}
+
 		$size = filesize($file_path);
 		if ( false === $size || $size > Workspace::MAX_READ_SIZE ) {
 			return array();
diff --git a/inc/Workspace/WorkspaceRepositoryLifecycle.php b/inc/Workspace/WorkspaceRepositoryLifecycle.php
index 88bc64a..b0036c5 100644
--- a/inc/Workspace/WorkspaceRepositoryLifecycle.php
+++ b/inc/Workspace/WorkspaceRepositoryLifecycle.php
@@ -36,8 +36,8 @@ public function list_repos( ?string $repo = null, ?string $type = null ): array|
 
 		$repo_filter = null !== $repo && '' !== trim($repo) ? $this->parse_handle($repo)['repo'] : null;
 		$type_filter = null !== $type && '' !== trim($type) ? strtolower(trim($type)) : null;
-		if ( null !== $type_filter && ! in_array($type_filter, array( 'primary', 'worktree' ), true) ) {
-			return new \WP_Error('invalid_workspace_type', 'Workspace list type must be "primary" or "worktree".', array( 'status' => 400 ));
+		if ( null !== $type_filter && ! in_array($type_filter, array( 'primary', 'worktree', 'context' ), true) ) {
+			return new \WP_Error('invalid_workspace_type', 'Workspace list type must be "primary", "worktree", or "context".', array( 'status' => 400 ));
 		}
 
 		if ( ! is_dir($path) ) {
@@ -51,63 +51,86 @@ public function list_repos( ?string $repo = null, ?string $type = null ): array|
 		$repos   = array();
 		$entries = scandir($path);
 
-		foreach ( $entries as $entry ) {
-			if ( '.' === $entry || '..' === $entry ) {
-				continue;
-			}
-
-			$entry_path = $path . '/' . $entry;
-			if ( ! is_dir($entry_path) ) {
-				continue;
-			}
+		if ( 'context' !== $type_filter ) {
+			foreach ( $entries as $entry ) {
+				if ( '.' === $entry || '..' === $entry ) {
+					continue;
+				}
 
-			$git_path = $entry_path . '/.git';
-			$is_git   = is_dir($git_path) || is_file($git_path);
-			$is_wt    = is_file($git_path);
-			$parsed   = $this->parse_handle($entry);
+				$entry_path = $path . '/' . $entry;
+				if ( ! is_dir($entry_path) ) {
+					continue;
+				}
 
-			if ( null !== $repo_filter && $parsed['repo'] !== $repo_filter ) {
-				continue;
-			}
+				$git_path = $entry_path . '/.git';
+				$is_git   = is_dir($git_path) || is_file($git_path);
+				$is_wt    = is_file($git_path);
+				$parsed   = $this->parse_handle($entry);
 
-			$is_worktree = $is_wt || $parsed['is_worktree'];
-			if ( 'primary' === $type_filter && $is_worktree ) {
-				continue;
-			}
-			if ( 'worktree' === $type_filter && ! $is_worktree ) {
-				continue;
-			}
+				if ( null !== $repo_filter && $parsed['repo'] !== $repo_filter ) {
+					continue;
+				}
 
-			$repo_info = array(
-				'name'        => $entry,
-				'path'        => $entry_path,
-				'git'         => $is_git,
-				'is_worktree' => $is_worktree,
-				'repo'        => $parsed['repo'],
-			);
+				$is_worktree = $is_wt || $parsed['is_worktree'];
+				if ( 'primary' === $type_filter && $is_worktree ) {
+					continue;
+				}
+				if ( 'worktree' === $type_filter && ! $is_worktree ) {
+					continue;
+				}
 
-			if ( $parsed['is_worktree'] ) {
-				$repo_info['branch_slug'] = $parsed['branch_slug'];
-			}
+				$repo_info = array(
+					'name'        => $entry,
+					'path'        => $entry_path,
+					'git'         => $is_git,
+					'is_worktree' => $is_worktree,
+					'repo'        => $parsed['repo'],
+				);
 
-			// Get git remote if available.
-			if ( $is_git ) {
-				$remote = $this->git_get_remote($entry_path);
-				if ( null !== $remote ) {
-					$repo_info['remote'] = $remote;
+				if ( $parsed['is_worktree'] ) {
+					$repo_info['branch_slug'] = $parsed['branch_slug'];
 				}
 
-				$branch = $this->git_get_branch($entry_path);
-				if ( null !== $branch ) {
-					$repo_info['branch'] = $branch;
+				// Get git remote if available.
+				if ( $is_git ) {
+					$remote = $this->git_get_remote($entry_path);
+					if ( null !== $remote ) {
+						$repo_info['remote'] = $remote;
+					}
+
+					$branch = $this->git_get_branch($entry_path);
+					if ( null !== $branch ) {
+						$repo_info['branch'] = $branch;
+					}
+
+					if ( ! $is_worktree ) {
+						$repo_info['primary_freshness'] = $this->build_primary_freshness_report($entry_path, $entry);
+					}
 				}
 
-				if ( ! $is_worktree ) {
-					$repo_info['primary_freshness'] = $this->build_primary_freshness_report($entry_path, $entry);
-				}
+				$repos[] = $repo_info;
 			}
+		}
+
+		if ( null === $type_filter || 'context' === $type_filter ) {
+			foreach ( WorkspaceAliasResolver::context_repositories() as $alias => $context ) {
+				if ( null !== $repo_filter && $this->parse_handle( (string) ( $context['target'] ?? $alias ) )['repo'] !== $repo_filter && $alias !== $repo_filter ) {
+					continue;
+				}
 
-			$repos[] = $repo_info;
+				$target  = (string) ( $context['target'] ?? $alias );
+				$path    = $this->workspace_path . '/' . $this->parse_handle($target)['dir_name'];
+				$repos[] = array(
+					'name'             => $alias,
+					'path'             => is_dir($path) ? $path : null,
+					'git'              => is_dir($path . '/.git') || is_file($path . '/.git'),
+					'is_worktree'      => false,
+					'is_context'       => true,
+					'repo'             => (string) ( $context['repo'] ?? $target ),
+					'ref'              => (string) ( $context['ref'] ?? '' ),
+					'workspace_policy' => WorkspaceAliasResolver::policy_attestation($alias),
+				);
+			}
 		}
 
 		return array(
@@ -149,8 +172,8 @@ public function clone_repo( string $url, ?string $name = null, array $options =
 			return new \WP_Error('invalid_clone_name', 'Repository names cannot contain "@". The "@<branch-slug>" suffix is reserved for worktrees (use "workspace worktree add" instead).', array( 'status' => 400 ));
 		}
 
-		$name      = $this->sanitize_name($name);
-		$repo_path = $this->workspace_path . '/' . $name;
+		$name                   = $this->sanitize_name($name);
+		$repo_path              = $this->workspace_path . '/' . $name;
 		$allow_duplicate_remote = ! empty($options['allow_duplicate_remote']);
 
 		// Check if already exists.
@@ -428,10 +451,10 @@ private function clone_remote_exists_error( string $url, string $name, array $ex
 			'repo_remote_exists',
 			sprintf('A primary checkout for %s already exists as "%s" at %s. Do not clone the same remote as "%s"; refresh/reuse the existing primary instead. Next steps: %s', $url, $existing_name, (string) ( $existing['path'] ?? '' ), $name, implode(' ', $next_steps)),
 			array(
-				'status'   => 409,
-				'url'      => $url,
-				'name'     => $name,
-				'existing' => $existing,
+				'status'     => 409,
+				'url'        => $url,
+				'name'       => $name,
+				'existing'   => $existing,
 				'next_steps' => $next_steps,
 			)
 		);
@@ -620,6 +643,30 @@ public function remove_repo( string $handle ): array|\WP_Error {
 	 * @return array{success: bool, name?: string, path?: string, branch?: string, remote?: string, commit?: string, dirty?: int}|\WP_Error
 	 */
 	public function show_repo( string $handle ): array|\WP_Error {
+		$context_policy = WorkspaceAliasResolver::context_policy_for($handle);
+		if ( null !== $context_policy ) {
+			$target    = (string) ( $context_policy['target'] ?? $handle );
+			$parsed    = $this->parse_handle($target);
+			$repo_path = $this->workspace_path . '/' . $parsed['dir_name'];
+			$ref       = (string) ( $context_policy['ref'] ?? '' );
+			if ( ! is_dir($repo_path) ) {
+				return array(
+					'success'          => true,
+					'name'             => (string) $context_policy['alias'],
+					'repo'             => (string) ( $context_policy['repo'] ?? $target ),
+					'is_worktree'      => false,
+					'is_context'       => true,
+					'path'             => null,
+					'branch'           => '' !== $ref ? $ref : null,
+					'remote'           => '' !== (string) ( $context_policy['repo'] ?? '' ) ? 'https://github.com/' . (string) $context_policy['repo'] . '.git' : null,
+					'commit'           => null,
+					'dirty'            => 0,
+					'workspace_policy' => WorkspaceAliasResolver::policy_attestation($handle),
+				);
+			}
+			$handle = $target;
+		}
+
 		$parsed    = $this->parse_handle($handle);
 		$repo_path = $this->workspace_path . '/' . $parsed['dir_name'];
 
@@ -636,17 +683,23 @@ public function show_repo( string $handle ): array|\WP_Error {
 		$status = trim( (string) exec(sprintf('git -C %s status --porcelain 2>/dev/null | wc -l', $escaped)));
      // phpcs:enable
 
-		return array(
-			'success'     => true,
-			'name'        => $parsed['dir_name'],
-			'repo'        => $parsed['repo'],
-			'is_worktree' => $parsed['is_worktree'],
-			'path'        => $repo_path,
-			'branch'      => $branch ? $branch : null,
-			'remote'      => $remote ? $remote : null,
-			'commit'      => $commit ? $commit : null,
-			'dirty'       => (int) $status,
+		$result = array(
+			'success'           => true,
+			'name'              => null !== $context_policy ? (string) $context_policy['alias'] : $parsed['dir_name'],
+			'repo'              => $parsed['repo'],
+			'is_worktree'       => $parsed['is_worktree'],
+			'is_context'        => null !== $context_policy,
+			'path'              => $repo_path,
+			'branch'            => $branch ? $branch : null,
+			'remote'            => $remote ? $remote : null,
+			'commit'            => $commit ? $commit : null,
+			'dirty'             => (int) $status,
 			'primary_freshness' => ! $parsed['is_worktree'] ? $this->build_primary_freshness_report($repo_path, $parsed['dir_name']) : null,
 		);
+		if ( null !== $context_policy ) {
+			$result['workspace_policy'] = WorkspaceAliasResolver::policy_attestation($handle);
+		}
+
+		return $result;
 	}
 }
diff --git a/inc/Workspace/WorkspaceWriter.php b/inc/Workspace/WorkspaceWriter.php
index 49b9499..7e2b5cc 100644
--- a/inc/Workspace/WorkspaceWriter.php
+++ b/inc/Workspace/WorkspaceWriter.php
@@ -15,7 +15,6 @@
 
 namespace DataMachineCode\Workspace;
 
-use DataMachine\Core\FilesRepository\FilesystemHelper;
 use DataMachineCode\Support\GitRunner;
 use DataMachineCode\Support\PathSecurity;
 
@@ -50,6 +49,10 @@ public function __construct( Workspace $workspace ) {
 	 * @return array{success: bool, path?: string, size?: int, created?: bool}|\WP_Error
 	 */
 	public function write_file( string $name, string $path, string $content ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($name) ) {
+			return WorkspaceAliasResolver::mutation_error($name, 'write');
+		}
+
 		$repo_path = $this->workspace->get_repo_path($name);
 		$path      = ltrim($path, '/');
 
@@ -123,7 +126,10 @@ public function write_file( string $name, string $path, string $content ): array
 	 * @return array{success: bool, path?: string, replacements?: int}|\WP_Error
 	 */
 	public function edit_file( string $name, string $path, string $old_string, string $new_string, bool $replace_all = false ): array|\WP_Error {
-		$fs        = FilesystemHelper::get();
+		if ( WorkspaceAliasResolver::is_context_repository($name) ) {
+			return WorkspaceAliasResolver::mutation_error($name, 'edit');
+		}
+
 		$repo_path = $this->workspace->get_repo_path($name);
 		$path      = ltrim($path, '/');
 
@@ -135,16 +141,16 @@ public function edit_file( string $name, string $path, string $old_string, strin
 		$validation = $this->workspace->validate_containment($file_path, $repo_path);
 
 		if ( ! $validation['valid'] ) {
-			return new \WP_Error('path_traversal', $validation['message'], array( 'status' => 403 ));
+			return new \WP_Error('path_traversal', (string) ( $validation['message'] ?? 'Path traversal detected. Access denied.' ), array( 'status' => 403 ));
 		}
 
-		$real_path = $validation['real_path'];
+		$real_path = (string) ( $validation['real_path'] ?? '' );
 
 		if ( ! is_file($real_path) ) {
 			return new \WP_Error('file_not_found', sprintf('File not found: %s', $path), array( 'status' => 404 ));
 		}
 
-		if ( ! is_readable($real_path) || ! $fs->is_writable($real_path) ) {
+		if ( ! is_readable($real_path) || ! is_writable($real_path) ) { // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_is_writable
 			return new \WP_Error('file_not_writable', sprintf('File not readable/writable: %s', $path), array( 'status' => 403 ));
 		}
 
@@ -185,7 +191,10 @@ public function edit_file( string $name, string $path, string $old_string, strin
 		if ( $replace_all ) {
 			$new_content = str_replace($old_string, $new_string, $content);
 		} else {
-			$pos         = strpos($content, $old_string);
+			$pos = strpos($content, $old_string);
+			if ( false === $pos ) {
+				return new \WP_Error('string_not_found', 'old_string not found in file content.', array( 'status' => 400 ));
+			}
 			$new_content = substr_replace($content, $new_string, $pos, strlen($old_string));
 		}
 
@@ -215,6 +224,10 @@ public function edit_file( string $name, string $path, string $old_string, strin
 	 * @return array{success: bool, name: string, path: string, changed_files: string[], diff: string, status: string, check_output: string, apply_output: string}|\WP_Error
 	 */
 	public function apply_patch( string $name, string $patch, bool $allow_primary_mutation = false ): array|\WP_Error {
+		if ( WorkspaceAliasResolver::is_context_repository($name) ) {
+			return WorkspaceAliasResolver::mutation_error($name, 'apply-patch');
+		}
+
 		$repo_path = $this->workspace->get_repo_path($name);
 		$parsed    = $this->workspace->parse_handle($name);
 
diff --git a/tests/smoke-remote-workspace-backend.php b/tests/smoke-remote-workspace-backend.php
index f6c837d..a0c8c29 100644
--- a/tests/smoke-remote-workspace-backend.php
+++ b/tests/smoke-remote-workspace-backend.php
@@ -15,6 +15,10 @@ class GitHubAbilities
         'content' => "<?php\nreturn 'old';\n",
         'sha'     => 'file-sha-main-example',
         ),
+        'Automattic/studio:trunk:README.md' => array(
+        'content' => "Studio context\n",
+        'sha'     => 'file-sha-studio-readme',
+        ),
         );
         public static array $commits = array();
 
@@ -61,6 +65,7 @@ public static function getRepoTree( array $input ): array|\WP_Error
             'success' => true,
             'files'   => array(
             array( 'path' => 'src/example.php', 'type' => 'file', 'size' => 20 ),
+            array( 'path' => 'README.md', 'type' => 'file', 'size' => 15 ),
             ),
             );
         }
@@ -226,6 +231,28 @@ function update_option( string $key, mixed $value, bool $autoload = true ): bool
     $assert('push is successful compatibility no-op', ! is_wp_error($push) && 'fix/example' === $push['branch']);
     $assert('push backend result omits model-facing guidance', ! is_wp_error($push) && ! array_key_exists('next_required_tool', $push) && ! array_key_exists('next_required_args', $push));
 
+    update_option(
+        'datamachine_code_context_repositories',
+        array(
+            array(
+                'repo'  => 'Automattic/studio',
+                'ref'   => 'trunk',
+                'alias' => 'studio',
+                'paths' => array( 'README.md' ),
+            ),
+        )
+    );
+
+    $context_read = $backend->read_file('studio', 'README.md', 1000000);
+    $assert('remote context alias reads configured repo ref', ! is_wp_error($context_read) && str_contains($context_read['content'], 'Studio context'));
+    $assert('remote context read includes policy attestation', ! is_wp_error($context_read) && true === ( $context_read['workspace_policy']['read_only'] ?? false ));
+
+    $context_write = $backend->write_file('studio', 'README.md', "changed\n");
+    $assert('remote context write is rejected', is_wp_error($context_write) && 'context_repository_read_only' === $context_write->get_error_code());
+
+    $context_push = $backend->git_push('studio');
+    $assert('remote context push is rejected', is_wp_error($context_push) && 'context_repository_read_only' === $context_push->get_error_code());
+
     $second_worktree = $backend->worktree_add('example', 'fix/remove-me');
     $assert('second worktree add succeeds', ! is_wp_error($second_worktree) && 'example@fix-remove-me' === $second_worktree['handle']);
 
diff --git a/tests/smoke-workspace-context-repositories.php b/tests/smoke-workspace-context-repositories.php
new file mode 100644
index 0000000..440f648
--- /dev/null
+++ b/tests/smoke-workspace-context-repositories.php
@@ -0,0 +1,193 @@
+<?php
+/**
+ * Smoke test for read-only workspace context repositories.
+ *
+ * Run: php tests/smoke-workspace-context-repositories.php
+ */
+
+declare( strict_types=1 );
+
+if ( ! defined('ABSPATH') ) {
+	define('ABSPATH', sys_get_temp_dir() . '/dmc-workspace-context-repositories-abspath/');
+}
+
+if ( ! class_exists('WP_Error') ) {
+	class WP_Error {
+		public function __construct( private string $code, private string $message, private array $data = array() ) {}
+
+		public function get_error_code(): string {
+			return $this->code;
+		}
+
+		public function get_error_message(): string {
+			return $this->message;
+		}
+
+		public function get_error_data(): array {
+			return $this->data;
+		}
+	}
+}
+
+if ( ! function_exists('is_wp_error') ) {
+	function is_wp_error( mixed $value ): bool {
+		return $value instanceof WP_Error;
+	}
+}
+
+if ( ! function_exists('get_option') ) {
+	function get_option( string $name, mixed $default = false ): mixed {
+		return $GLOBALS['dmc_workspace_context_options'][ $name ] ?? $default;
+	}
+}
+
+if ( ! function_exists('apply_filters') ) {
+	function apply_filters( string $tag, mixed $value ): mixed {
+		return $value;
+	}
+}
+
+if ( ! function_exists('size_format') ) {
+	function size_format( int|float $bytes ): string {
+		return (string) $bytes . ' B';
+	}
+}
+
+require __DIR__ . '/../vendor/autoload.php';
+require __DIR__ . '/../inc/Workspace/Workspace.php';
+require __DIR__ . '/../inc/Workspace/WorkspaceAliasResolver.php';
+require __DIR__ . '/../inc/Workspace/WorkspaceReader.php';
+require __DIR__ . '/../inc/Workspace/WorkspaceWriter.php';
+
+use DataMachineCode\Workspace\Workspace;
+use DataMachineCode\Workspace\WorkspaceReader;
+use DataMachineCode\Workspace\WorkspaceWriter;
+
+$failures = array();
+$total    = 0;
+$assert   = function ( string $label, bool $condition ) use ( &$failures, &$total ): void {
+	++$total;
+	if ( $condition ) {
+		echo "  ok {$label}\n";
+		return;
+	}
+
+	$failures[] = $label;
+	echo "  fail {$label}\n";
+};
+
+$run = static function ( string $command, string $cwd ): string {
+	$output = array();
+	$code   = 0;
+	// phpcs:ignore WordPress.PHP.DiscouragedPHPFunctions.system_calls_exec
+	exec(sprintf('cd %s && %s 2>&1', escapeshellarg($cwd), $command), $output, $code);
+	if ( 0 !== $code ) {
+		throw new RuntimeException(sprintf("Command failed (%d): %s\n%s", $code, $command, implode("\n", $output)));
+	}
+	return implode("\n", $output);
+};
+
+$write = static function ( string $path, string $content ): void {
+	$dir = dirname($path);
+	if ( ! is_dir($dir) ) {
+		mkdir($dir, 0777, true);
+	}
+	file_put_contents($path, $content);
+};
+
+echo "Workspace context repositories - smoke\n";
+
+$tmp = sys_get_temp_dir() . '/dmc-workspace-context-' . bin2hex(random_bytes(4));
+mkdir($tmp, 0777, true);
+if ( ! defined('DATAMACHINE_WORKSPACE_PATH') ) {
+	define('DATAMACHINE_WORKSPACE_PATH', $tmp);
+}
+
+$context_repo = $tmp . '/studio';
+mkdir($context_repo, 0777, true);
+$run('git init -q', $context_repo);
+$run('git config user.email tester@example.com', $context_repo);
+$run('git config user.name Tester', $context_repo);
+$write($context_repo . '/README.md', "Studio contract\n");
+$write($context_repo . '/docs/contract.md', "Tool contract\n");
+$write($context_repo . '/src/private.php', "private contract\n");
+$run('git add README.md docs/contract.md src/private.php && git commit -q -m initial', $context_repo);
+
+$target = $tmp . '/target@feature';
+mkdir($target, 0777, true);
+$run('git init -q', $target);
+$run('git config user.email tester@example.com', $target);
+$run('git config user.name Tester', $target);
+$write($target . '/README.md', "target\n");
+$run('git add README.md && git commit -q -m initial', $target);
+
+$GLOBALS['dmc_workspace_context_options'] = array(
+	'datamachine_code_context_repositories' => array(
+		array(
+			'repo'  => 'Automattic/studio',
+			'ref'   => 'trunk',
+			'alias' => 'studio',
+			'paths' => array( 'README.md', 'docs/**' ),
+		),
+	),
+);
+
+$workspace = new Workspace();
+$reader    = new WorkspaceReader($workspace);
+$writer    = new WorkspaceWriter($workspace);
+
+$list = $workspace->list_repos(null, 'context');
+$assert('workspace_list exposes context repository row', ! is_wp_error($list) && 'studio' === ( $list['repos'][0]['name'] ?? '' ));
+$assert('context list row is read-only', ! is_wp_error($list) && false === ( $list['repos'][0]['workspace_policy']['writable'] ?? true ));
+
+$show = $workspace->show_repo('studio');
+$assert('workspace_show emits context attestation', ! is_wp_error($show) && true === ( $show['workspace_policy']['read_only'] ?? false ));
+
+$read = $reader->read_file('studio', 'README.md');
+$assert('allowed context file can be read', ! is_wp_error($read) && str_contains((string) ( $read['content'] ?? '' ), 'Studio contract'));
+$assert('read result includes context policy', ! is_wp_error($read) && false === ( $read['workspace_policy']['writable'] ?? true ));
+
+$blocked_read = $reader->read_file('studio', 'src/private.php');
+$assert('disallowed context file is rejected', is_wp_error($blocked_read) && 'context_repository_path_not_allowed' === $blocked_read->get_error_code());
+
+$root_list = $reader->list_directory('studio');
+$root_names = ! is_wp_error($root_list) ? array_column($root_list['entries'] ?? array(), 'name') : array();
+$assert('context directory listing includes allowed root entry', in_array('docs', $root_names, true) && in_array('README.md', $root_names, true));
+$assert('context directory listing hides disallowed root entry', ! in_array('src', $root_names, true));
+
+$grep = $reader->grep('studio', 'contract');
+$grep_paths = ! is_wp_error($grep) ? array_column($grep['matches'] ?? array(), 'path') : array();
+$assert('context grep searches allowed paths', in_array('README.md', $grep_paths, true) && in_array('docs/contract.md', $grep_paths, true));
+$assert('context grep skips disallowed paths', ! in_array('src/private.php', $grep_paths, true));
+
+$write_blocked = $writer->write_file('studio', 'docs/new.md', "nope\n");
+$assert('context write is rejected', is_wp_error($write_blocked) && 'context_repository_read_only' === $write_blocked->get_error_code());
+
+$edit_blocked = $writer->edit_file('studio', 'README.md', 'Studio', 'Edited');
+$assert('context edit is rejected', is_wp_error($edit_blocked) && 'context_repository_read_only' === $edit_blocked->get_error_code());
+
+$patch_blocked = $writer->apply_patch('studio', "diff --git a/README.md b/README.md\n--- a/README.md\n+++ b/README.md\n@@ -1 +1 @@\n-Studio contract\n+Edited contract\n");
+$assert('context apply-patch is rejected', is_wp_error($patch_blocked) && 'context_repository_read_only' === $patch_blocked->get_error_code());
+
+$git_add_blocked = $workspace->git_add('studio', array( 'README.md' ), true);
+$assert('context git add is rejected', is_wp_error($git_add_blocked) && 'context_repository_read_only' === $git_add_blocked->get_error_code());
+
+$git_commit_blocked = $workspace->git_commit('studio', 'Update context', true);
+$assert('context git commit is rejected', is_wp_error($git_commit_blocked) && 'context_repository_read_only' === $git_commit_blocked->get_error_code());
+
+$git_push_blocked = $workspace->git_push('studio', 'origin', 'trunk', true);
+$assert('context git push is rejected', is_wp_error($git_push_blocked) && 'context_repository_read_only' === $git_push_blocked->get_error_code());
+
+$target_write = $writer->write_file('target@feature', 'changed.txt', "target remains writable\n");
+$assert('target worktree remains writable', ! is_wp_error($target_write) && true === ( $target_write['success'] ?? false ));
+
+if ( ! empty($failures) ) {
+	echo "\nFAIL: " . count($failures) . " assertion(s) failed out of {$total}\n";
+	foreach ( $failures as $failure ) {
+		echo "  - {$failure}\n";
+	}
+	exit(1);
+}
+
+echo "\nOK ({$total} assertions)\n";
+exit(0);