feat(tui): make pi-tui the default renderer

pi-tui reached parity and then some — copy mode, image paste, history
search, ghost suggestions, dynamic title, and a differential renderer
that doesn't flicker or churn on long transcripts. It's now the default;
CODEBASE_REACT_TUI=1 falls back to legacy ink during the deprecation
window.

Author: halfaipg

CLAUDE.md

@@ -96,12 +96,21 @@ SEARXNG_URL             self-hosted SearXNG instance
 ### Behavior toggles
 ```
 CODEBASE_FRESH=1              skip auto-resume of prior session (same as --new)
+CODEBASE_REACT_TUI=1          legacy ink renderer (pi-tui is the default)
 CODEBASE_NO_SUGGESTIONS=1     disable ghost-text prompt suggestions
+CODEBASE_NO_NOTIFY=1          silence the turn-completion bell + OS notification
 CODEBASE_DEBUG=1              verbose stderr logging
 CODEBASE_DEBUG_INPUT=1        log every keystroke to ~/.codebase/logs/input.log
 NO_HYPERLINK=1                disable OSC 8 clickable file paths
 ```
 
+The default UI is **pi-tui** (differential renderer): Ctrl-O copy-mode
+(clean OSC-52 copy of code/`present_copy` boxes), Ctrl-V image paste,
+Ctrl-R history search, ghost suggestions, dynamic terminal title. New
+slash commands: `/effort <off…xhigh>` (reasoning level), `/permissions`
+(view/edit allow-deny rules), `/resume` (multi-session picker),
+`/export`, `/doctor`, `/skills`, `/agents`.
+
 ### Unrestricted mode (trust-the-developer escape hatches)
 
 By default the agent has three soft guards. Each one has an opt-out

src/cli.tsx

@@ -119,16 +119,17 @@ if (argv[0] === "--version" || argv[0] === "-v") {
 	// back to the login wizard. A network failure here is silent — the
 	// wizard path catches it downstream.
 	await ensureFreshCredentials();
-	if (process.env.CODEBASE_PI_TUI === "1") {
-		// Opt-in pi-tui render path — differential renderer, no React.
-		// During the migration this is feature-gated; the ink path stays
-		// default until parity is verified.
+	// pi-tui (differential renderer, no React) is the default. It has the
+	// full feature set plus click-free copy mode, dynamic title, and
+	// smoother streaming on long transcripts. CODEBASE_REACT_TUI=1 falls
+	// back to the legacy ink path during the deprecation window.
+	if (process.env.CODEBASE_REACT_TUI !== "1") {
 		const { runPiTuiApp } = await import("./ui-pi/runtime.js");
 		installTerminalRestoreHandlers();
 		await runPiTuiApp();
 		process.exit(0);
 	}
-	// Default ink/React path. Disable ink's default ctrl-c handling — ink
+	// Legacy ink/React path. Disable ink's default ctrl-c handling — ink
 	// unmounts on ctrl-c but doesn't exit the process — leaves the user
 	// staring at a frozen terminal. We handle ctrl-c ourselves.
 	const instance = render(<App />, { exitOnCtrlC: false });

src/ui-pi/runtime.ts

@@ -4,7 +4,8 @@ import { App } from "./app.js";
 import { FirstRunWizard } from "./first-run-wizard.js";
 
 /**
- * Entry point for the pi-tui render path (CODEBASE_PI_TUI=1). Mirrors
+ * Entry point for the pi-tui render path (the default; CODEBASE_REACT_TUI=1
+ * falls back to legacy ink). Mirrors
  * `render(<App />)` from cli.tsx's ink path but constructs a pi-tui
  * TUI with our root `App` Container instead. Returns when the App
  * resolves its exit promise.