feat(#2100): drive Windsurf through the EoS descriptor + wire Cascade's blocking hook bus (ADR-1239)

Fold all 10 residual isWindsurf branches in bin/install.js onto descriptor-driven
hostBehaviors (byte-parity — no fold changes any install output):
- 2 dead destructures dropped (uninstall, finishInstall); the dead
  `else if (isWindsurf)` legacy agent-loop arm removed (windsurf ∈
  _DESCRIPTOR_AGENTS_RUNTIMES → unreachable).
- skipSharedHooksInstall:true folds the two `!isWindsurf` shared-hooks exclusions.
- legacyDevinSkillsCleanup:true folds the `.devin`→`.windsurf` one-time cleanup gate.
- installsCommandBodiesForWorkflowDelegation:true folds the #1629 command-body copy
  (workflow-delegation target — load-bearing; local-install verified intact).
- verificationStyle:"windsurf-workflows" folds the workflow-count report.
- Corrected stale _LEGACY_SCAN_SUBDIR_NAMES + hooks-json manifest comments (cursor + windsurf).
Zero live runtime==='windsurf'/isWindsurf branches remain across bin/install.js,
install-engine.cts, surface.cts, runtime-artifact-conversion.cts (AC2 guard scans all four).

UPGRADE (Cascade hook bus): wire GSD's write/command safety guards into Windsurf's
native hook bus. New hooksSurface 'windsurf-hooks-json' (VALID_HOOKS_SURFACES 7→8, GATE A
profile-marker-only allowlist, the HooksSurface union) + writeWindsurfHooksJson
(Cursor-templated, Cascade's flat {hooks:{<event>:[{command}]}} shape) writing
.windsurf/hooks.json with two BLOCKING pre-hooks:
- pre_write_code → gsd-windsurf-pre-write.js: blocks writes to a file outside the
  active git worktree / into .git internals.
- pre_run_command → gsd-windsurf-pre-command.js: conservative destructive-command
  deny-list (rm -rf of root/home incl. sudo/env/path-prefixed forms; fork bombs;
  force-push refspec forms — HEAD:main, +main, --force/-f — to main/master/next).
Both use Cascade's protocol (stdin JSON, exit 2 + stderr to block, exit 0 to allow,
fail-open on error/timeout). Tokenize-based classifier (no catastrophic-backtracking regex;
4096-char cap) with the fail-closed false-positives fixed post-review.

The 4 advisory GSD guards + pre_mcp_tool_use + 5 post_* logging events are deliberately
NOT wired: Cascade has no context-injection channel for advisory hooks and GSD has no MCP
guard — porting them would be non-functional padding (documented; codebuddy #2098 / copilot
#2099 faithful-subset precedent). extendedHookEvents stays [].

Golden: the 2 guard scripts ship in the shared hook bundle (HOOKS_TO_COPY + the shared
managed-hooks-registry), exactly like cursor's 6 gsd-cursor-*.js scripts — so the 8
shared-bundle runtimes' fixtures gain the 2 inert windsurf scripts + the registry hash
(functionally inert for non-windsurf; the established cursor pattern). No install-output
change beyond that (the folds are byte-parity; skip-bundle runtimes untouched). New scripts
registered in managed-hooks-registry + build-hooks + INVENTORY. Tests: declarative-reference-
windsurf (adapter/axes/fail-closed + AC2 guard) + windsurf-hooks-bridge (live exit-2 blocking
+ allow/fail-open + ReDoS-bound + writer/reconcile/remove idempotency); VALID_HOOKS_SURFACES
pin updated to 8. Matrix hookBus delta + changeset (Changed). capability-registry regenerated.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/reference/host-integration-capability-matrix.md

@@ -508,7 +508,7 @@ Documentation gaps:
 | embeddingMode | declarative | https://docs.devin.ai/desktop/cascade/cascade | "Cascade operates through configuration files rather than code plugins: .codeiumignore for file filtering, Memories and Rules for customizing" |
 | commandSurface | slash-file | https://docs.devin.ai/desktop/cascade/workflows | "Workflows are authored as markdown files (.md extension) … triggered through slash commands using the format /[workflow-name]." |
 | modelMode | passive | https://docs.devin.ai/desktop/models.md | "Models are selectable via configuration/UI only (SWE-1.5, SWE-1.6, Adaptive, Arena tiers, Claude, GPT)." |
-| hookBus | host | https://docs.devin.ai/desktop/cascade/hooks.md | "Cascade supports twelve hook events covering critical workflow points … Pre-hooks (can block actions): pre_read_code, pre_write_code, pre_ru" |
+| hookBus | host | https://docs.devin.ai/desktop/cascade/hooks.md | "Cascade supports twelve hook events covering critical workflow points … Pre-hooks (can block actions): pre_read_code, pre_write_code, pre_run_command, …" (quote elided beyond the pre-hook enumeration — see #2100 CASCADE FACTS reference) |
 | stateIO | filesystem | https://docs.devin.ai/desktop/cascade/cascade | "Cascade can create and modify codebases directly … File access can be restricted through .codeiumignore files" |
 | transport | mcp | https://docs.devin.ai/desktop/cascade/mcp | "Cascade now natively integrates with MCP, allowing you to bring your own selection of MCP servers for Cascade to use." |
 | runtime | undocumented | no authoritative doc — searched: https://docs.devin.ai/windsurf/plugins/getting-started.md, /llmstxt/windsurf_llms-full_txt (Context7) | — |
@@ -537,6 +537,8 @@ Documentation gaps:
 - dispatch.subagentToolkit — no documentation for toolkit restrictions on Cascade sub-agents.
 - runtime — Windsurf IDE is Electron-based but no programmatic plugin runtime is documented to developers.
 
+**EoS migration status (#2100 Stage 2 — HOOK-BRIDGE):** `hooksSurface` moved from `"none"` to `"windsurf-hooks-json"`. GSD now wires two of Cascade's documented pre-hooks with BLOCKING semantics via `.windsurf/hooks.json` (local) / `~/.codeium/windsurf/hooks.json` (global): `pre_write_code` (write-path guard — blocks a write resolving to a different git root than cwd, or into a `.git/` internals directory) and `pre_run_command` (a conservative destructive-command deny-list — whole-disk/home `rm -rf`, force-push to a protected branch). Cascade blocks via **exit code 2** (+ a stderr reason string) — a materially different protocol from Cursor's stdout-JSON `{block, reason}` hooks.json form, even though the surrounding install/reconcile infra (`writeWindsurfHooksJson`/`removeWindsurfHooksJson` in `src/runtime-hooks-surface.cts`) mirrors `writeCursorHooksJson`/`removeCursorHooksJson`'s shape. Cascade has **no context-injection channel** (no `additional_context`-style advisory response channel), so the 4 advisory hook events GSD registers on Cursor (`sessionStart`, `postToolUse`, `stop`, `subagentStart`/`subagentStop`) have no Windsurf/Cascade counterpart and are deliberately **not ported** — only the 2 events with a genuine blocking analog are wired. `installSurface` stays `profile-marker-only` (unchanged); the hook bus is wired from inside that branch, gated on `hooksSurface === 'windsurf-hooks-json'` rather than a hardcoded runtime check.
+
 ---
 
 ## trae