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ADR 0110: Roslyn Range Refactorings - Intent Melody/IDE Bridge and Roslyn MCP

Status: Proposed
Date: 2026-05-11

ADR Role
0081 parametric tail :start:end, §3 about refactorings
0109 directory [[melody_root]], build args in code
0058 pairing an agent with Roslyn MCP
0030 command_id

Outside ADR

Document Role
roslyn-mcp separate MCP server

Context

Full C# refactorings (Extract Method, Extract Interface, etc.) in the Cascade ecosystem are implemented in the Roslyn MCP process: roslyn_get_code_actions and roslyn_apply_code_action with an optional range (end_line, end_column) - see the tool diagrams and ServiceLayer/CodeActions.cs in the roslyn-mcp repository.

The CascadeIDE core does not duplicate the Microsoft.CodeAnalysis.CSharp.Features and MSBuildWorkspace stack for the same operations: the in-process editor uses simplified semantics (CSharpLanguageService) without a full code actions pipeline.

Previously discussed mnemonic like rmx / rix (0081); do not store stubs in the code without a real command_id - this is out of sync with the catalog and palette.

Problem

  1. The user expects one line c:... or IdeCommands leading to the same result as manually calling Roslyn MCP.
  2. Duplicate implementation of refactorings inside CascadeIDE.exe is expensive and at odds with the single source of truth in roslyn-mcp.
  3. We need an explicit architectural place for the future solution (bridge, delegation, settings), without dummy entries in TOML.

Solution (direction)

  1. Canon of range operations in the IDE core for today: already implemented layers - select (select), replace text (apply_edit), URL portal, etc. through the catalog 0109.
  2. Extract Method / Extract Interface and analogs up to a separate ADR Accepted do not declare mandatory slugs in intent-melody-aliases.toml. Options for the next iteration (mutually exclusive or combinable - decide upon implementation):
  3. Agent/external host calls Roslyn MCP with the same solution/project path and range after the IDE has set the selection (c:els:… or equivalent).
  4. Optional bridge in IDE: configurable path (localhost MCP, stdio, future in-proc host) and thin command_id that serializes intent + range and delegates to roslyn-mcp - see 0058.

  5. Rejection of individual mnemonics rmx/rix in favor of the documented script “select range → code actions in Roslyn MCP”.

  6. Catalog stubs without command_id in the bundle do not use - violate the invariant 0109 (execution via command_id + args).

Consequences

  • Document 0081 with reference to this ADR fixes the border: el* - in the core product zone; r* and Roslyn refactorings - after an explicit bridge or only through an external MCP.
  • Implementation of the bridge - separate commits: contract args, settings, tests, if necessary, new IdeCommands and regeneration of ProtocolDocGen.

Rejected alternatives (briefly)

Alternative Why not now
Embed CSharp.Features + MSBuildWorkspace entirely in CascadeIDE Duplication of roslyn-mcp, heavy pipeline, deployment size
Leave rmx/rix in TOML without execution Confuses palette and chord (0060)