Add Copilot support and fix Windows startup

.github/hooks/rtk-rewrite.json

@@ -3,7 +3,7 @@
     "PreToolUse": [
       {
         "type": "command",
-        "command": "rtk hook",
+        "command": "rtk hook copilot",
         "cwd": ".",
         "timeout": 5
       }

INSTALL.md

@@ -78,6 +78,10 @@ rtk gain  # MUST show token savings, not "command not found"
   │         Hook + RTK.md (~10 tokens in context)
   │         Commands auto-rewritten transparently
   │
+  ├─ GitHub Copilot everywhere → rtk init -g --agent copilot
+  │         Global Copilot instructions in ~/.copilot/copilot-instructions.md
+  │         Helps both Copilot CLI and VS Code Copilot Chat use rtk
+  │
   ├─ YES, minimal → rtk init -g --hook-only
   │         Hook only, nothing added to CLAUDE.md
   │         Zero tokens in context
@@ -109,6 +113,26 @@ rtk init --show  # Check hook is installed and executable
 
 **Token savings**: ~99.5% reduction (2000 tokens → 10 tokens in context)
 
+### GitHub Copilot Setup
+
+**Best for: GitHub Copilot CLI and VS Code Copilot Chat**
+
+```bash
+# Global instructions for all Copilot sessions
+rtk init -g --agent copilot
+
+# Repository-local instructions + PreToolUse hook
+rtk init --agent copilot
+```
+
+Global mode writes `~/.copilot/copilot-instructions.md`, which Copilot CLI and VS Code Copilot Chat both load automatically.
+
+Repository mode writes:
+- `.github/copilot-instructions.md`
+- `.github/hooks/rtk-rewrite.json`
+
+The repository hook runs `rtk hook copilot`, which is cross-platform and works on Windows without `bash` or `jq`.
+
 **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.
 

README.md

@@ -287,6 +287,45 @@ rtk init --show             # Verify installation
 
 After install, **restart Claude Code**.
 
+## GitHub Copilot Support
+
+RTK supports both GitHub Copilot CLI and VS Code Copilot Chat.
+
+**Global instructions for Copilot (recommended for VS Code):**
+```bash
+rtk init -g --agent copilot
+```
+
+This writes `~/.copilot/copilot-instructions.md`, which Copilot CLI and VS Code Copilot Chat both load automatically.
+
+**Repository hook + instructions (for a specific repo):**
+```bash
+rtk init --agent copilot
+```
+
+This creates:
+- `.github/copilot-instructions.md`
+- `.github/hooks/rtk-rewrite.json`
+
+The hook uses the native Rust processor directly:
+
+```json
+{
+  "hooks": {
+    "PreToolUse": [
+      {
+        "type": "command",
+        "command": "rtk hook copilot",
+        "cwd": ".",
+        "timeout": 5
+      }
+    ]
+  }
+}
+```
+
+This is cross-platform and works on Windows without shell wrappers or `jq`.
+
 ## Gemini CLI Support (Global)
 
 RTK supports Gemini CLI via a native Rust hook processor. The hook intercepts `run_shell_command` tool calls and rewrites them to `rtk` equivalents using the same rewrite engine as Claude Code.

build.rs

@@ -3,6 +3,15 @@ use std::fs;
 use std::path::Path;
 
 fn main() {
+    #[cfg(windows)]
+    {
+        // Clap + the full command graph can exceed the default 1 MiB Windows
+        // main-thread stack during process startup. Reserve a larger stack for
+        // the CLI binary so `rtk.exe --version`, `--help`, and hook entry
+        // points start reliably without requiring ad-hoc RUSTFLAGS.
+        println!("cargo:rustc-link-arg=/STACK:8388608");
+    }
+
     let filters_dir = Path::new("src/filters");
     let out_dir = std::env::var("OUT_DIR").expect("OUT_DIR must be set by Cargo");
     let dest = Path::new(&out_dir).join("builtin_filters.toml");

hooks/copilot-global-rtk-awareness.md

@@ -0,0 +1,40 @@
+# RTK - Copilot Global Instructions
+
+**Usage**: Token-optimized CLI proxy (60-90% savings on dev operations)
+
+This file is intended for `~/.copilot/copilot-instructions.md` so GitHub Copilot CLI and VS Code Copilot Chat can load RTK guidance globally.
+
+## Golden Rule
+
+Always prefer `rtk` for shell commands that produce verbose output.
+
+Examples:
+
+```bash
+rtk git status
+rtk git diff
+rtk cargo test
+rtk npm run build
+rtk pytest -q
+rtk docker ps
+```
+
+## Meta Commands
+
+```bash
+rtk gain              # Show token savings analytics
+rtk gain --history    # Show command usage history with savings
+rtk discover          # Analyze sessions for missed RTK usage
+rtk proxy <cmd>       # Run raw command without filtering
+```
+
+## Verification
+
+```bash
+rtk --version
+rtk gain
+where rtk            # Windows
+which rtk            # macOS/Linux
+```
+
+⚠️ **Name collision**: If `rtk gain` fails, you may have the wrong `rtk` installed.

hooks/copilot-rtk-awareness.md

@@ -7,7 +7,7 @@
 The `.github/copilot-instructions.md` file is loaded at session start by both Copilot CLI and VS Code Copilot Chat.
 It instructs Copilot to prefix commands with `rtk` automatically.
 
-The `.github/hooks/rtk-rewrite.json` hook adds a `PreToolUse` safety net via `rtk hook` —
+The `.github/hooks/rtk-rewrite.json` hook adds a `PreToolUse` safety net via `rtk hook copilot` —
 a cross-platform Rust binary that intercepts raw bash tool calls and rewrites them.
 No shell scripts, no `jq` dependency, works on Windows natively.
 
@@ -33,21 +33,21 @@ which rtk       # Verify correct binary path
 
 ## How the hook works
 
-`rtk hook` reads `PreToolUse` JSON from stdin, detects the agent format, and responds appropriately:
+`rtk hook copilot` reads `PreToolUse` JSON from stdin, detects the agent format, and responds appropriately:
 
 **VS Code Copilot Chat** (supports `updatedInput` — transparent rewrite, no denial):
-1. Agent runs `git status` → `rtk hook` intercepts via `PreToolUse`
-2. `rtk hook` detects VS Code format (`tool_name`/`tool_input` keys)
+1. Agent runs `git status` → `rtk hook copilot` intercepts via `PreToolUse`
+2. `rtk hook copilot` detects VS Code format (`tool_name`/`tool_input` keys)
 3. Returns `hookSpecificOutput.updatedInput.command = "rtk git status"`
 4. Agent runs the rewritten command silently — no denial, no retry
 
 **GitHub Copilot CLI** (deny-with-suggestion — CLI ignores `updatedInput` today, see [issue #2013](https://github.com/github/copilot-cli/issues/2013)):
-1. Agent runs `git status` → `rtk hook` intercepts via `PreToolUse`
-2. `rtk hook` detects Copilot CLI format (`toolName`/`toolArgs` keys)
+1. Agent runs `git status` → `rtk hook copilot` intercepts via `PreToolUse`
+2. `rtk hook copilot` detects Copilot CLI format (`toolName`/`toolArgs` keys)
 3. Returns `permissionDecision: deny` with reason: `"Token savings: use 'rtk git status' instead"`
 4. Copilot reads the reason and re-runs `rtk git status`
 
-When Copilot CLI adds `updatedInput` support, only `rtk hook` needs updating — no config changes.
+When Copilot CLI adds `updatedInput` support, only `rtk hook copilot` needs updating — no config changes.
 
 ## Integration comparison