Implementation Tasks

1. Adapter

1.1 Add src/core/command-generation/adapters/devin.ts: .devin/workflows/opsx-<id>.md, frontmatter name/description/category/tags via the shared helpers in command-generation/yaml.ts.
1.2 Keep the adapter a pure formatter: the opsx- filename prefix makes Devin a flat invocation, so the generator rewrites /opsx:<id> body references to /opsx-<id> — the name Devin registers for a workflow file.
1.3 Delete adapters/windsurf.ts and its registry/barrel entries; register devinAdapter in their place.

2.1 Replace the windsurf row in AI_TOOLS with devin (skillsDir: '.devin', detectionPaths: ['.devin', '.windsurf']). Detection, the init picker, --tools validation, update, and profile sync all derive from this row.
2.2 Add TOOL_ID_ALIASES / resolveToolIdAlias in src/core/config.ts and apply it when parsing --tools, so --tools windsurf still resolves.
2.3 Re-key the pre-opsx .windsurf/workflows/openspec-*.md entry in LEGACY_SLASH_COMMAND_PATHS to devin — that map's keys are tool ids.
2.4 In getTransformerForTool, give devin the skill-reference transformer whenever skills are generated, so skill bodies and the getting-started hint say /openspec-* — the Devin Local agent has no workflows. Under commands-only delivery, fall through to the invocation rewrite.

3.1 Replace LEGACY_SKILLS_DIRS with LEGACY_TOOL_ROOTS, each root carrying whether leaving it needs consent (.kimi no, .windsurf yes).
3.2 Extend the move to command files, deriving the legacy path from the adapter's own getFilePath so no layout is hard-coded. Skip absolute paths.
3.3 Split find from apply (findLegacyToolMigrations / migrateLegacyToolDirs) so a consent-gated move can be described before it happens.
3.4 openspec update: explain the rebrand, prompt interactively, migrate under --force or non-interactively, and say plainly what declining costs.
3.5 openspec init: treat selecting the tool as consent and migrate for the selected tools only.

4.1 docs/supported-tools.md: give Devin its own row in the authoritative "How To Invoke" table — the catch-all row would otherwise claim /opsx-<id> for both agents. Replace the Windsurf directory row and rewrite the footnote to cover the rename, the alias, and the migration.
4.2 Drop windsurf from the --tools ID lists in docs/cli.md and docs/supported-tools.md, noting it is still accepted as an alias.
4.3 Update the command-syntax tables in docs/commands.md and docs/how-commands-work.md, plus prose mentions in faq.md, migration-guide.md, opsx.md, and the website tool list.

5.1 Adapter: tool id, getFilePath, and frontmatter. Hyphen rewriting is asserted end to end in the generateCommand flat-tool loop, and YAML escaping by the registry-derived parity matrix — both enroll Devin automatically.
5.2 Detection: .devin and legacy .windsurf both resolve to devin; neither present means not detected.
5.3 Alias: --tools windsurf writes .devin/ and leaves no .windsurf/.
5.4 Migration: skills and workflows move, user-authored files in .windsurf/ survive, and a second run migrates nothing.
5.5 init/update: both surfaces — .devin/workflows/opsx-*.md carry /opsx-*, .devin/skills/openspec-*/SKILL.md carry /openspec-*, and neither carries /opsx:.
5.6 getTransformerForTool returns the skill transformer for Devin under both/skills delivery and the hyphen form under commands.

6.1 openspec validate add-devin-desktop-support --strict.
6.2 openspec archive add-devin-desktop-support --yes merges cleanly and additively (run on a scratch copy, then reverted).
6.3 Full suite green.
6.4 Manual journeys in scratch repos: legacy .windsurf install upgraded; both directories populated; IDE-written .devin/rules/ preserved; --tools windsurf alias.