Workspace Session Undo

You manage session-scoped history for Roslyn MCP applies. You do not replace git.

Input

Identify `workspaceId` (from `workspace_list` or the session the user is using).

Server discovery

MCP prompt `session_undo` summarizes this workflow. Full inventory: `roslyn://server/catalog`.

Workflow

1. `workspace_changes` — list mutations (tool, files, timestamps) for the session.
2. `revert_last_apply` — undo only the latest solution-level apply for that workspaceId.
3. `workspace_reload` — re-read from disk when files changed outside MCP or the snapshot is stale (confirm with the user when destructive).
4. `workspace_close` — tear down the session when finished.

Atomic apply + verify (v1.15+)

`apply_with_verify(previewToken, rollbackOnError=true)` wraps the three-step pattern (apply → compile_check → revert_last_apply on new errors) in a single atomic call. Prefer it over the manual chain when you're applying a preview whose outcome you're not sure about.

• On a clean apply: returns {status: "applied", appliedFiles: [...]}.
• On new compile errors with rollbackOnError=true (default): returns {status: "rolled_back", introducedErrors: [...]} and the workspace is back to the pre-apply state.
• Pass rollbackOnError=false to preserve the broken state for manual inspection (returns {status: "applied_with_errors"}).

Diff view — what changed since a previous apply point

When the user asks "what has this session changed?" or "show me the diff since the last apply," produce a structured diff view without committing to an undo:

1. `workspace_changes` — pull the session ledger (tool name, files, timestamps, optional preview token if still live).
2. For each file in the ledger, show the current-vs-original state:

• Prefer the server's own change record (if workspace_changes returns pre-/post-apply text snippets or a preview-token-backed diff).
• Otherwise read the current file via get_source_text, then cross-reference with git diff if the repo has git (assume the user controls the working tree; do not shell out without asking).

1. Group by apply-event timestamp, with a heading per event showing tool + affected files.
2. At the bottom, offer next actions:

• revert_last_apply to undo the most recent apply
• workspace_reload if on-disk state drifted from the workspace snapshot
• Manual git rollback for multi-step undo

This mode is read-only — don't mutate anything without explicit user direction.

Limits

• `revert_last_apply` is one step — not arbitrary history.
• For multi-step rollback use git or manual edits.
• After reload or revert, run `compile_check` or `build_workspace`.
• Diff view relies on what workspace_changes records in this session; applies from a previous session are not in scope — use git for cross-session history.