code-actions

Roslyn Code Actions

You help apply Roslyn code actions exposed by the MCP host: list actions at a span, preview the diff, apply with the preview token, then validate.

Input

From $ARGUMENTS (or the user's message), obtain:

• Absolute filePath
• startLine, startColumn (1-based)
• Optionally endLine, endColumn for selection-range refactorings (e.g. introduce parameter, inline temporary)

If a workspace is not loaded, ask for the solution path and call workspace_load first.

Server discovery

Use server_info, roslyn://server/catalog, MCP prompt discover_capabilities (refactoring), or refactor_and_validate when you already know the span and want a templated workflow message.

Safety rules

1. Preview before apply: preview_code_action → review diff → apply_code_action.
2. Verify after apply: compile_check or build_project / build_workspace.
3. One change at a time unless the user explicitly asked for a batch.

Workflow

1. Call get_code_actions with workspaceId, filePath, startLine, startColumn, and end coordinates if the user highlighted a range.
2. Present the numbered actions. Ask which index to run if unclear.
3. Call preview_code_action with that index. Show the diff summary.
4. After confirmation, call apply_code_action with the preview token.
5. Run compile_check (fast) or build_workspace.
6. If the result is wrong, consider revert_last_apply then retry with a different action or span.

For diagnostics-first flows, combine with diagnostic_details, code_fix_preview / code_fix_apply, or fix_all_preview when fixing every instance of one ID.

Filter by safety

get_code_actions often returns 10+ actions at any given span, mixing safe renames/introduce-local/inline-variable with higher-risk moves/restructures. Filter them into three tiers before presenting:

Tier	Examples of action titles	Recommended default
Safe	"Inline temporary variable", "Introduce local", "Use expression body", "Convert to auto-property", "Add/remove modifier", "Use var / explicit type", "Add missing using", "Sort usings", "Remove unused using", "Use pattern matching", "Use nameof", "Use ?? / ??=", "Use compound assignment"	Safe to auto-apply under --auto-apply-safe
Structural	"Extract method", "Introduce parameter", "Encapsulate field", "Convert to record", "Make class sealed", "Move declaration near reference"	Present and confirm per-action
Risky	"Move type to new file", "Move type to new namespace", "Remove async modifier", "Convert between await and Task.Run", anything involving cross-file moves	Present with a warning; never auto-apply

Workflow with the filter:

1. Call get_code_actions as usual.
2. Classify each action title against the table above. When ambiguous, treat as Structural.
3. If the user passed --auto-apply-safe, preview + apply every Safe-tier action at once via composite preview when possible, then run compile_check.
4. Otherwise, present the tiered list and let the user pick.

This filter is a heuristic — action titles vary by analyzer version. When a title doesn't match any row, default to Structural (confirm per-action). A user can override the classification for a specific action by name.