fix(opencode): route webfetch through the WebFetch redirect (#1052)

[gegemeimingzi]

What / Why / How

Fixes #1052.

What — Add the missing OpenCode webfetch alias to TOOL_ALIASES in hooks/core/routing.mjs:

"fetch": "WebFetch",
"webfetch": "WebFetch",   // +1 line — opencode registers its fetch tool as `webfetch`
"agent": "Agent",

Why — OpenCode registers its fetch tool as webfetch (Tool.define("webfetch")), but TOOL_ALIASES only mapped "fetch". The alias lookup missed, canonical stayed webfetch, and the if (canonical === "WebFetch") redirect branch never matched — so the tool executed as a plain allow with zero routing interception (the page bytes enter the conversation, no ctx_fetch_and_index / ctx_search redirect).

How — One-line alias addition, same shape as the neighbouring "fetch": "WebFetch" entry. Hook-only change: hooks/core/routing.mjs is plain JS loaded fresh on each invocation, no rebuild needed (per CONTRIBUTING "What needs rebuild?").

Affected platforms

• Claude Code
• Cursor
• VS Code Copilot (GitHub Copilot)
• JetBrains Copilot
• Gemini CLI
• Qwen Code
• OpenCode
• KiloCode
• Codex CLI
• OpenClaw (Pi Agent)
• Pi
• Kiro
• Antigravity
• Zed
• All platforms

Test plan

TDD (red → green) — added one test to the existing tests/hooks/core-routing.test.ts (WebFetch domain, per CONTRIBUTING "Do NOT create new test files"):

• Red: routePreToolUse("webfetch", { url }, …, "opencode", …) → null (no interception) — test failed as expected
• Green: after the alias, the same call → { action: "deny", reason: "WebFetch redirected … ctx_fetch_and_index … ctx_search" }
• tests/hooks/core-routing.test.ts: 96/96 pass
• npm run typecheck: passes

Real-path verification (no OpenCode CLI on this machine, so done via the compiled plugin's actual hook surface): loaded the compiled build/adapters/opencode/plugin.js and invoked its real tool.execute.before hook with a webfetch payload:

• with the alias: throws the redirect error (context-mode: WebFetch redirected. Call context-mode_ctx_fetch_and_index(url: …)) → OpenCode blocks the call
• without the alias (stashed): passes through — reproduces the bug exactly

tool.execute.before's deny path in this plugin is throw Error, which OpenCode catches and turns into a denied tool call — so the throw observed is the same interception a live OpenCode session would hit.

Honest note on npm test: the full suite on this Windows box reports pre-existing environment failures unrelated to this change — EPERM on symlink creation (Windows needs admin to create symlinks) in tests/core/cli.test.ts, missing Python runtime + POSIX-shell expectations in tests/executor.test.ts, and temp-dir cleanup EPERM in session-path tests. I verified this by stashing my change and running the suite on the untouched next baseline: the same failures appear (49–57 failed depending on run). The routing suite itself (tests/hooks/core-routing.test.ts) passes 96/96 with the change.

Checklist

• Tests added/updated (TDD: red → green)
• npm test passes — routing suite 96/96; full-suite failures are pre-existing Windows-environment failures (verified identical on unmodified next baseline; see Test plan)
• npm run typecheck passes
• Docs updated if needed (README, platform-support.md) — n/a, one-line alias
• No Windows path regressions (forward slashes only)
• Targets next branch (unless hotfix)