feat: add text clipboard copy/read with mouse selection support

Add cross-platform text clipboard operations (macOS, Linux, Windows)
with OSC 52 support for SSH/tmux environments. Wire up onMouseUp and
Ctrl+Y in the TUI to copy selected text to the system clipboard via
OpenTUI's renderer selection API.

src/constants/clipboard.ts

@@ -0,0 +1,23 @@
+/**
+ * Clipboard constants for text copy/read operations
+ */
+
+/** OSC 52 escape sequence for clipboard write (insert base64 payload) */
+export const OSC52_SEQUENCE_PREFIX = "\x1b]52;c;";
+export const OSC52_SEQUENCE_SUFFIX = "\x07";
+
+/** DCS tmux passthrough wrapping */
+export const TMUX_DCS_PREFIX = "\x1bPtmux;\x1b";
+export const TMUX_DCS_SUFFIX = "\x1b\\";
+
+/** Environment variables indicating tmux/screen session */
+export const TMUX_ENV_VAR = "TMUX";
+export const SCREEN_ENV_VAR = "STY";
+export const WAYLAND_DISPLAY_ENV_VAR = "WAYLAND_DISPLAY";
+
+/** Platform command timeout in milliseconds */
+export const CLIPBOARD_COMMAND_TIMEOUT_MS = 5000;
+
+/** Supported MIME types for clipboard content */
+export const CLIPBOARD_MIME_TEXT = "text/plain" as const;
+export const CLIPBOARD_MIME_IMAGE_PNG = "image/png" as const;

src/constants/mouse-handler.ts

@@ -26,11 +26,38 @@ export const PARTIAL_X10_REGEX = /\x1b\[M.{0,2}$/;
 // Mouse tracking escape sequences
 export const MOUSE_TRACKING_SEQUENCES = {
   ENABLE_BUTTON: "\x1b[?1000h",
+  ENABLE_BUTTON_EVENT: "\x1b[?1002h",
   ENABLE_SGR: "\x1b[?1006h",
   DISABLE_SGR: "\x1b[?1006l",
+  DISABLE_BUTTON_EVENT: "\x1b[?1002l",
   DISABLE_BUTTON: "\x1b[?1000l",
 } as const;
 
+// Enable button-event tracking + SGR encoding (for scroll + drag selection)
+export const MOUSE_TRACKING_ENABLE =
+  MOUSE_TRACKING_SEQUENCES.ENABLE_BUTTON_EVENT +
+  MOUSE_TRACKING_SEQUENCES.ENABLE_SGR;
+
+// Mouse button action codes (SGR encoding)
+export const MOUSE_BUTTON = {
+  LEFT_PRESS: 0,
+  MIDDLE_PRESS: 1,
+  RIGHT_PRESS: 2,
+  LEFT_DRAG: 32,
+  MIDDLE_DRAG: 33,
+  RIGHT_DRAG: 34,
+  SCROLL_UP: 64,
+  SCROLL_DOWN: 65,
+} as const;
+
+// Disable button-event tracking + SGR encoding
+export const MOUSE_TRACKING_DISABLE =
+  MOUSE_TRACKING_SEQUENCES.DISABLE_BUTTON_EVENT +
+  MOUSE_TRACKING_SEQUENCES.DISABLE_SGR;
+
+// Time in ms to re-enable mouse tracking after selection ends
+export const MOUSE_SELECTION_REENABLE_MS = 2000;
+
 // Scroll direction type
 export type MouseScrollDirection = "up" | "down";
 

src/constants/plan-approval.ts

@@ -0,0 +1,58 @@
+/**
+ * Plan Approval Constants
+ *
+ * Options and configuration for the plan approval prompt,
+ * modeled after Claude Code's plan approval flow.
+ */
+
+/** How edits should be handled after plan approval */
+export type PlanEditMode =
+  | "auto_accept_clear"   // Clear context and auto-accept edits
+  | "auto_accept"         // Auto-accept edits
+  | "manual_approve"      // Manually approve each edit
+  | "feedback";           // User provides feedback/changes
+
+/** A selectable option in the plan approval modal */
+export interface PlanApprovalOption {
+  key: string;
+  label: string;
+  description: string;
+  editMode: PlanEditMode;
+  shortcut?: string;
+}
+
+/** Available plan approval options, matching Claude Code's pattern */
+export const PLAN_APPROVAL_OPTIONS: PlanApprovalOption[] = [
+  {
+    key: "1",
+    label: "Yes, clear context and auto-accept edits",
+    description: "Approve plan, clear conversation context, and auto-accept all file edits",
+    editMode: "auto_accept_clear",
+    shortcut: "shift+tab",
+  },
+  {
+    key: "2",
+    label: "Yes, auto-accept edits",
+    description: "Approve plan and auto-accept all file edits without prompting",
+    editMode: "auto_accept",
+  },
+  {
+    key: "3",
+    label: "Yes, manually approve edits",
+    description: "Approve plan but require manual approval for each file edit",
+    editMode: "manual_approve",
+  },
+  {
+    key: "4",
+    label: "Type here to tell CodeTyper what to change",
+    description: "Provide feedback or modifications to the plan",
+    editMode: "feedback",
+  },
+];
+
+/** Maximum visible options before scrolling */
+export const PLAN_APPROVAL_MAX_VISIBLE_OPTIONS = 4;
+
+/** Footer help text for plan approval modal */
+export const PLAN_APPROVAL_FOOTER_TEXT =
+  "ctrl-g to edit in editor";

src/constants/terminal.ts

@@ -7,3 +7,14 @@ export const DISABLE_MOUSE_TRACKING =
   "\x1b[?1003l" + // All mouse events (motion)
   "\x1b[?1002l" + // Button event mouse tracking
   "\x1b[?1000l"; // Normal tracking mode
+
+/**
+ * Full terminal reset sequence for cleanup on exit
+ * Disables all tracking modes, restores cursor, exits alternate screen
+ */
+export const TERMINAL_RESET =
+  DISABLE_MOUSE_TRACKING +
+  "\x1b[?25h" + // Show cursor
+  "\x1b[?1049l" + // Leave alternate screen
+  "\x1b[>4;0m" + // Disable Kitty keyboard protocol (pop)
+  "\x1b[?2004l"; // Disable bracketed paste mode

src/constants/thinking-tags.ts

@@ -0,0 +1,30 @@
+/**
+ * Thinking Tags Constants
+ *
+ * XML tag names that LLM providers use for reasoning/thinking blocks.
+ * These should be stripped from visible streaming output and displayed
+ * as dimmed thinking indicators instead.
+ */
+
+/** Tag names to strip from streaming content */
+export const THINKING_TAGS = [
+  "thinking",
+  "search",
+  "plan",
+  "execute",
+] as const;
+
+export type ThinkingTagName = (typeof THINKING_TAGS)[number];
+
+/** Regex pattern to match a complete opening tag: <thinking>, <search>, etc. */
+export const THINKING_OPEN_TAG_REGEX = new RegExp(
+  `<(${THINKING_TAGS.join("|")})>`,
+);
+
+/** Regex pattern to match a complete closing tag: </thinking>, </search>, etc. */
+export const THINKING_CLOSE_TAG_REGEX = new RegExp(
+  `</(${THINKING_TAGS.join("|")})>`,
+);
+
+/** Maximum buffer size before flushing as visible text (safety valve) */
+export const THINKING_BUFFER_MAX_SIZE = 256;