feat: add OpenCode support and fix hook basename detection

ARCHITECTURE.md

@@ -71,20 +71,22 @@ $ 3 commits      ←─  Terminal      ←─   Format      ←─   Compact Sta
 4. **Fail-Safe**: If filtering fails, fall back to original output
 5. **Transparent**: Users can always see raw output with `-v` flags
 
-### Hook Architecture (v0.9.5+)
+### Hook/Plugin Architecture (v0.9.5+)
 
-The recommended deployment mode uses a Claude Code PreToolUse hook for 100% transparent command rewriting.
+The recommended deployment mode uses platform-specific hooks for 100% transparent command rewriting:
+- **Claude Code**: PreToolUse hook (`rtk-rewrite.sh`) registered in `settings.json`
+- **OpenCode**: TypeScript plugin (`rtk-rewrite.ts`) auto-loaded from `~/.config/opencode/plugins/`
 
 ```
 ┌────────────────────────────────────────────────────────────────────────┐
 │                    Hook-Based Command Rewriting                        │
 └────────────────────────────────────────────────────────────────────────┘
 
-Claude Code             settings.json        rtk-rewrite.sh        RTK binary
+AI Agent               Hook/Plugin          Rewrite Logic         RTK binary
      │                       │                     │                    │
      │  Bash: "git status"   │                     │                    │
      │ ─────────────────────►│                     │                    │
-     │                       │  PreToolUse hook    │                    │
+     │                       │  Intercept trigger  │                    │
      │                       │ ───────────────────►│                    │
      │                       │                     │  detect: git       │
      │                       │                     │  rewrite:          │
@@ -99,12 +101,16 @@ Claude Code             settings.json        rtk-rewrite.sh        RTK binary
      │◄──────────────────────────────────────────────────────────────────
      │  "3 modified, 1 untracked ✓"    (~10 tokens vs ~200 raw)
      │
-     │  Claude never sees the rewrite — it only sees optimized output.
+     │  The agent never sees the rewrite — it only sees optimized output.
 
-Files:
+Files (Claude Code):
   ~/.claude/hooks/rtk-rewrite.sh  ← shell script (command detection + rewrite)
   ~/.claude/settings.json         ← hook registry (PreToolUse registration)
   ~/.claude/RTK.md                ← minimal context hint (10 lines)
+
+Files (OpenCode):
+  ~/.config/opencode/plugins/rtk-rewrite.ts  ← TS plugin (auto-loaded)
+  ~/.config/opencode/AGENTS.md               ← rules file (optional)
 ```
 
 Two hook strategies:

INSTALL.md

@@ -72,7 +72,7 @@ rtk gain  # MUST show token savings, not "command not found"
 ### Which mode to choose?
 
 ```
-  Do you want RTK active across ALL Claude Code projects?
+  Do you want RTK active across ALL AI agent projects?
   │
   ├─ YES → rtk init -g              (recommended)
   │         Hook + RTK.md (~10 tokens in context)
@@ -110,14 +110,14 @@ rtk init --show  # Check hook is installed and executable
 **Token savings**: ~99.5% reduction (2000 tokens → 10 tokens in context)
 
 **What is settings.json?**
-Claude Code's hook registry. RTK adds a PreToolUse hook that rewrites commands transparently. Without this, Claude won't invoke the hook automatically.
+Claude Code's hook registry (OpenCode uses auto-loaded plugins instead). RTK adds a PreToolUse hook that rewrites commands transparently. Without this, the hook won't be invoked automatically.
 
 ```
-  Claude Code          settings.json        rtk-rewrite.sh        RTK binary
+  AI Agent             Hook/Plugin          Rewrite Logic         RTK binary
        │                    │                     │                    │
        │  "git status"      │                     │                    │
        │ ──────────────────►│                     │                    │
-       │                    │  PreToolUse trigger  │                    │
+       │                    │  Intercept trigger   │                    │
        │                    │ ───────────────────►│                    │
        │                    │                     │  rewrite command   │
        │                    │                     │  → rtk git status  │
@@ -172,7 +172,7 @@ rtk init -g
 # → Answer 'y' when prompted to patch settings.json
 # → Creates backup automatically
 
-# 3. Restart Claude Code
+# 3. Restart your AI agent (Claude Code or OpenCode)
 # 4. Test: git status (should use rtk)
 ```
 
@@ -191,8 +191,8 @@ rtk init --show | grep "Hook:"
 rtk init -g --no-patch
 
 # Review printed JSON snippet
-# Manually edit ~/.claude/settings.json
-# Restart Claude Code
+# Manually edit ~/.claude/settings.json (Claude Code only)
+# Restart your AI agent
 ```
 
 ### Temporary Trial
@@ -237,7 +237,7 @@ rtk init -g --uninstall
 #   - Reference: @RTK.md line from ~/.claude/CLAUDE.md
 #   - Registration: RTK hook entry from settings.json
 
-# Restart Claude Code after uninstall
+# Restart your AI agent after uninstall
 ```
 
 **For Local Projects**: Manually remove RTK block from `./CLAUDE.md`
@@ -309,7 +309,7 @@ rtk gain --history    # With command history
 | `pnpm list` | ~8,000 tokens | ~2,400 | **-70%** |
 | `pnpm outdated` | ~12,000 tokens | ~1,200-2,400 | **-80-90%** |
 
-### Typical Claude Code Session (30 min)
+### Typical AI Agent Session (30 min)
 - **Without RTK**: ~150,000 tokens
 - **With RTK**: ~45,000 tokens
 - **Savings**: **70% reduction**