chore: import upstream snapshot with attribution

hooks/opencode/README.md

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+# OpenCode Hooks
+
+> Part of [`hooks/`](../README.md) — see also [`src/hooks/`](../../src/hooks/README.md) for installation code
+
+## Specifics
+
+- TypeScript plugin using the zx library (not a shell hook)
+- Intercepts `tool.execute.before` events, calls `rtk rewrite` as a subprocess
+- Uses `.quiet().nothrow()` to silently ignore failures
+- Mutates `args.command` in-place if rewrite differs from original
+- Installed to `~/.config/opencode/plugins/rtk.ts` by `rtk init -g --opencode`

hooks/opencode/rtk.ts

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+import type { Plugin } from "@opencode-ai/plugin"
+
+// RTK OpenCode plugin — rewrites commands to use rtk for token savings.
+// Requires: rtk >= 0.23.0 in PATH.
+//
+// This is a thin delegating plugin: all rewrite logic lives in `rtk rewrite`,
+// which is the single source of truth (src/discover/registry.rs).
+// To add or change rewrite rules, edit the Rust registry — not this file.
+
+export const RtkOpenCodePlugin: Plugin = async ({ $ }) => {
+  try {
+    await $`which rtk`.quiet()
+  } catch {
+    console.warn("[rtk] rtk binary not found in PATH — plugin disabled")
+    return {}
+  }
+
+  return {
+    "tool.execute.before": async (input, output) => {
+      const tool = String(input?.tool ?? "").toLowerCase()
+      if (tool !== "bash" && tool !== "shell") return
+      const args = output?.args
+      if (!args || typeof args !== "object") return
+
+      const command = (args as Record<string, unknown>).command
+      if (typeof command !== "string" || !command) return
+
+      try {
+        const result = await $`rtk rewrite ${command}`.quiet().nothrow()
+        const rewritten = String(result.stdout).trim()
+        if (rewritten && rewritten !== command) {
+          ;(args as Record<string, unknown>).command = rewritten
+        }
+      } catch {
+        // rtk rewrite failed — pass through unchanged
+      }
+    },
+  }
+}