diff --git a/AGENTS.md b/AGENTS.md
index ca22970..d4b4947 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -30,15 +30,15 @@ Surface hierarchy (strict — do not blur these in code, docs, or UI copy):
 ## Stack
 
 - Native UI: GPUI with `alacritty_terminal` as the terminal model and render buffer.
-- Application core: Rust, SQLite via `rusqlite`, exposed by `crates/runner-app`.
+- Application core: Rust, SQLite via `rusqlite`, exposed by `crates/runner-backend`.
 - PTY runtime: `portable-pty`.
 - Event transport: append-only NDJSON logs watched through `notify`.
 - Bundled CLI: `runner`, built from the `cli/` workspace member.
 
 ## Project Map
 
-- `crates/runner-native/`: GPUI application, terminal renderer, composer, and terminal fixture corpus.
-- `crates/runner-app/`: UI-agnostic application core, including SQLite, session manager, event bus, router, and MCP server.
+- `crates/runner-app/`: GPUI application, terminal renderer, and terminal fixture corpus.
+- `crates/runner-backend/`: UI-agnostic application core, including SQLite, session manager, event bus, router, and MCP server.
 - `cli/`: bundled `runner` CLI used by spawned agents.
 - `crates/runner-core/`: shared event-log primitives.
 - `design/`: Pencil source files.
@@ -56,7 +56,7 @@ Surface hierarchy (strict — do not blur these in code, docs, or UI copy):
 - Workspace tests: `make test`.
 - Everything CI runs: `make verify` (check + test + clippy + fmt-check).
 
-Prefer the smallest check that covers the change. For native UI changes, run the `runner-native` tests plus workspace clippy; for core behavior, run the relevant crate tests.
+Prefer the smallest check that covers the change. For native UI changes, run the `runner-app` tests plus workspace clippy; for core behavior, run the relevant crate tests.
 
 ## Engineering Conventions
 
diff --git a/Cargo.lock b/Cargo.lock
index 5a1017b..ad3c17c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4873,6 +4873,24 @@ checksum = "6c20b6793b5c2fa6553b250154b78d6d0db37e72700ae35fad9387a46f487c97"
 [[package]]
 name = "runner-app"
 version = "0.3.17"
+dependencies = [
+ "alacritty_terminal",
+ "anyhow",
+ "base64",
+ "futures",
+ "gpui-ce",
+ "runner-backend",
+ "runner-terminal",
+ "serde",
+ "serde_json",
+ "tempfile",
+ "tokio",
+ "unicode-segmentation",
+]
+
+[[package]]
+name = "runner-backend"
+version = "0.3.17"
 dependencies = [
  "base64",
  "chrono",
@@ -4927,24 +4945,6 @@ dependencies = [
  "ulid",
 ]
 
-[[package]]
-name = "runner-native"
-version = "0.3.17"
-dependencies = [
- "alacritty_terminal",
- "anyhow",
- "base64",
- "futures",
- "gpui-ce",
- "runner-app",
- "runner-terminal",
- "serde",
- "serde_json",
- "tempfile",
- "tokio",
- "unicode-segmentation",
-]
-
 [[package]]
 name = "runner-terminal"
 version = "0.3.17"
@@ -4952,7 +4952,7 @@ dependencies = [
  "alacritty_terminal",
  "anyhow",
  "base64",
- "runner-app",
+ "runner-backend",
  "serde",
  "serde_json",
  "tempfile",
diff --git a/Cargo.toml b/Cargo.toml
index 32075fa..500af30 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,9 +1,9 @@
 [workspace]
 resolver = "2"
 members = [
-    "crates/runner-app",
+    "crates/runner-backend",
     "crates/runner-core",
-    "crates/runner-native",
+    "crates/runner-app",
     "crates/runner-terminal",
     "cli",
 ]
diff --git a/Makefile b/Makefile
index 57cfc38..94c9172 100644
--- a/Makefile
+++ b/Makefile
@@ -21,4 +21,4 @@ test:
 verify: check test clippy fmt-check
 
 run:
-	cargo run -p runner-native
+	cargo run -p runner-app
diff --git a/crates/runner-app/Cargo.toml b/crates/runner-app/Cargo.toml
index f50b538..9f577b4 100644
--- a/crates/runner-app/Cargo.toml
+++ b/crates/runner-app/Cargo.toml
@@ -1,58 +1,27 @@
 [package]
 name = "runner-app"
 version = "0.3.17"
-description = "UI-agnostic application core for Runner: command bodies, session manager, event bus, router, and MCP server"
 edition.workspace = true
 authors.workspace = true
+publish = false
+default-run = "runner-app"
 
-[lib]
-name = "runner_app"
+[[bin]]
+name = "runner-app"
+path = "src/main.rs"
 
 [dependencies]
-runner-core = { path = "../runner-core" }
-log = "0.4"
-serde = { workspace = true }
-serde_json = { workspace = true }
+alacritty_terminal = "0.26"
+anyhow = "1"
 base64 = "0.22"
-rusqlite = { version = "0.32", features = ["bundled", "chrono", "serde_json"] }
-# Derived row<->struct mapping for the repo layer (impl 0021). 0.36.x is
-# the release whose rusqlite dependency is 0.32, matching the workspace
-# rusqlite exactly so the Row types unify.
-serde_rusqlite = "0.36"
-r2d2 = "0.8"
-r2d2_sqlite = "0.25"
-chrono = { workspace = true }
-thiserror = { workspace = true }
-ulid = { workspace = true }
-uuid = { workspace = true }
-# Regular dep (not dev-only) because the sidecar writer needs
-# NamedTempFile::persist for a Windows-safe atomic replace.
-tempfile = "3"
-# Filesystem watcher for the per-mission event-log tail (C7). The
-# `macos_fsevent` backend is the default on macOS; on Linux it falls back to
-# inotify, on Windows to ReadDirectoryChangesW.
-notify = "6"
-# MCP server (impl 0013): Unix socket listener for external clients.
-# The `runner-mcp` sidecar bridges stdio ↔ this socket.
-rmcp = { version = "1.7", features = ["server"] }
-schemars = "1"
-tokio = { version = "1", features = ["net", "rt", "io-util", "sync"] }
-tokio-util = { version = "0.7", features = ["rt"] }
-# Codex MCP config lives in ~/.codex/config.toml; toml_edit preserves
-# user-authored comments + formatting on round-trip writes.
-toml_edit = "0.25"
-
-# Unix-only deps:
-#  - libc: FIFO mkfifo + poll() inside session::tmux_runtime.
-#  - portable-pty: backing crate for session::pty_runtime, the
-#    in-process replacement for tmux (impl 0011). Windows keeps the
-#    tmux fallback until a named-pipe equivalent lands.
-[target.'cfg(unix)'.dependencies]
-libc = "0.2"
-portable-pty = "0.9"
+futures = "0.3"
+gpui = { package = "gpui-ce", version = "0.3" }
+runner-backend = { path = "../runner-backend" }
+runner-terminal = { path = "../runner-terminal" }
+serde.workspace = true
+serde_json.workspace = true
+tokio = { version = "1", features = ["sync"] }
+unicode-segmentation = "1"
 
 [dev-dependencies]
-# Used by issue #124's forwarder-contention regression test to hold the
-# event-log flock from a second fd; matches the version `runner-core`
-# pulls in transitively so the trait impl resolves identically.
-fs2 = "0.4"
+tempfile = "3"
diff --git a/crates/runner-native/README.md b/crates/runner-app/README.md
similarity index 87%
rename from crates/runner-native/README.md
rename to crates/runner-app/README.md
index 064ddc4..89a4946 100644
--- a/crates/runner-native/README.md
+++ b/crates/runner-app/README.md
@@ -1,6 +1,6 @@
-# runner-native
+# runner-app
 
-Phase 3 walking skeleton for [the gpui-rewrite plan](../../docs/impls/gpui-rewrite/plan.md). It opens Runner's existing direct chats from the same SQLite database as the released app, spawns or resumes them through `runner_app::session::SessionManager`, and renders the manager's PTY byte stream with `alacritty_terminal` on GPUI.
+Phase 3 walking skeleton for [the gpui-rewrite plan](../../docs/impls/gpui-rewrite/plan.md). It opens Runner's existing direct chats from the same SQLite database as the released app, spawns or resumes them through `runner_backend::session::SessionManager`, and renders the manager's PTY byte stream with `alacritty_terminal` on GPUI.
 
 ## Run
 
@@ -17,8 +17,8 @@ GPUI requires the Xcode 26 Metal Toolchain component, already installed on the d
 Recorded PTY byte logs in `fixtures/*.ndjson` (header line + base64 data/input/exit events), replayed into a headless `Term` and compared against blessed `*.snapshot.txt` grids:
 
 ```sh
-cargo test -p runner-native
-UPDATE_SNAPSHOTS=1 cargo test -p runner-native
+cargo test -p runner-app
+UPDATE_SNAPSHOTS=1 cargo test -p runner-app
 ```
 
 Current corpus: `claude-session` (real interactive TUI boot → prompt → streamed reply → /exit palette), `top-busy` (full-screen redraw churn), `width-torture` (CJK/emoji/ZWJ/box-drawing/SGR glyph classes).
diff --git a/crates/runner-native/src/bootstrap.rs b/crates/runner-app/src/bootstrap.rs
similarity index 96%
rename from crates/runner-native/src/bootstrap.rs
rename to crates/runner-app/src/bootstrap.rs
index 37be842..5742aad 100644
--- a/crates/runner-native/src/bootstrap.rs
+++ b/crates/runner-app/src/bootstrap.rs
@@ -2,7 +2,7 @@ use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
 use anyhow::{bail, Context as _, Result};
-use runner_app::{db, event_bus, events, mcp, repo, session, shell_path, windows, AppCore};
+use runner_backend::{db, event_bus, events, mcp, repo, session, shell_path, windows, AppCore};
 
 pub const APP_IDENTIFIER: &str = "com.wycstudios.runner";
 
@@ -62,7 +62,7 @@ pub fn boot_core(paths: &NativePaths) -> Result<AppCore> {
         app_data_dir: paths.app_data_dir.clone(),
         sessions,
         buses: event_bus::BusRegistry::new(),
-        routers: runner_app::router::RouterRegistry::new(),
+        routers: runner_backend::router::RouterRegistry::new(),
         mcp: Arc::new(mcp::McpHandle::new()),
         windows: window_registry,
         events: events::EventChannel::new(),
@@ -148,7 +148,7 @@ mod tests {
             app_data_dir: PathBuf::new(),
             sessions: session::SessionManager::new(shell_path::LoginShellEnv::default(), runtime),
             buses: event_bus::BusRegistry::new(),
-            routers: runner_app::router::RouterRegistry::new(),
+            routers: runner_backend::router::RouterRegistry::new(),
             mcp: Arc::new(mcp::McpHandle::new()),
             windows: Arc::new(windows::WindowRegistry::new()),
             events: events::EventChannel::new(),
diff --git a/crates/runner-native/src/chat.rs b/crates/runner-app/src/chat.rs
similarity index 97%
rename from crates/runner-native/src/chat.rs
rename to crates/runner-app/src/chat.rs
index 2516149..c2c4ccf 100644
--- a/crates/runner-native/src/chat.rs
+++ b/crates/runner-app/src/chat.rs
@@ -33,7 +33,7 @@ impl NativeRoot {
         window: &mut Window,
         cx: &mut Context<Self>,
     ) -> Result<()> {
-        let _entry = runner_app::ops::session::session_get(&self.core, session_id)?
+        let _entry = runner_backend::ops::session::session_get(&self.core, session_id)?
             .with_context(|| format!("direct chat not found: {session_id}"))?;
         let pane_id = layout
             .root
@@ -194,14 +194,14 @@ impl NativeRoot {
             return;
         };
         let keystroke = &event.keystroke;
-        if runner_native::terminal_ime::terminal_key_route(
+        if runner_app::terminal_ime::terminal_key_route(
             chat.terminal_input.read(cx).is_composing(),
             keystroke.modifiers.platform,
             keystroke.modifiers.control,
             keystroke.modifiers.alt,
             keystroke.modifiers.function,
             &keystroke.key,
-        ) != runner_native::terminal_ime::TerminalKeyRoute::Raw
+        ) != runner_app::terminal_ime::TerminalKeyRoute::Raw
         {
             return;
         }
@@ -310,7 +310,7 @@ impl NativeRoot {
         };
         let mut spawned_id = None;
         let result = (|| -> Result<String> {
-            let spawned = runner_app::ops::session::session_start_direct(
+            let spawned = runner_backend::ops::session::session_start_direct(
                 &self.core,
                 runner_id.to_owned(),
                 None,
@@ -371,7 +371,7 @@ impl NativeRoot {
                 .get(session_id)
                 .map(|chat| chat.terminal.size())
                 .unwrap_or_else(|| self.estimated_terminal_size(&layout, pane_id, window));
-            runner_app::ops::session::session_resume(
+            runner_backend::ops::session::session_resume(
                 &self.core,
                 session_id,
                 Some(size.0),
@@ -434,7 +434,7 @@ impl NativeRoot {
             .active()
             .context("active tab is missing")?
             .upsert_input()?;
-        runner_app::ops::node::node_tab_upsert(&self.core, input)?;
+        runner_backend::ops::node::node_tab_upsert(&self.core, input)?;
         Ok(())
     }
 
diff --git a/crates/runner-app/src/lib.rs b/crates/runner-app/src/lib.rs
index e806645..1ba78fe 100644
--- a/crates/runner-app/src/lib.rs
+++ b/crates/runner-app/src/lib.rs
@@ -1,91 +1,5 @@
-// Runner's UI-agnostic application core (impl 0031 Phase 2).
-//
-// Everything a frontend needs to run Runner lives here: the SQLite layer,
-// the PTY session manager, the per-mission event bus + signal router, the
-// MCP server, and the command bodies (`ops`). Frontends — the Tauri app
-// today, the native GPUI binary in Phase 3 — are thin adapters: they build
-// an `AppCore`, subscribe to its event channel, and delegate their command
-// surface to `ops::*`.
-
-pub mod cli_install;
-pub mod db;
-pub mod error;
-pub mod event_bus;
-pub mod events;
-pub mod mcp;
-pub mod model;
-pub mod ops;
-pub mod repo;
-pub mod router;
-pub mod session;
-pub mod shell_path;
-pub mod windows;
-
-use std::path::PathBuf;
-use std::sync::Arc;
-
-use events::EventChannel;
-use session::manager::CoreSessionEvents;
-
-/// Shared application state. One instance per process, cheap to clone
-/// (every field is an `Arc` or small value) — the Tauri layer stores it in
-/// `app.manage`, the MCP handler clones it per connection.
-#[derive(Clone)]
-pub struct AppCore {
-    pub db: Arc<db::DbPool>,
-    /// Root of the app's per-user data tree — `$APPDATA/runner/` on real
-    /// installs, a tempdir in tests. Mission commands resolve event-log paths
-    /// relative to this via `runner_core::event_log::path`.
-    pub app_data_dir: PathBuf,
-    /// Live per-mission session manager. Created at app
-    /// start, shared across all frontends and the per-session
-    /// forwarder threads it spawns.
-    pub sessions: Arc<session::SessionManager>,
-    /// Live per-mission event-bus watchers. Mounted by `mission_start` once
-    /// the opening events are durable; unmounted by `mission_stop` and on
-    /// any rollback path.
-    pub buses: Arc<event_bus::BusRegistry>,
-    /// Live per-mission signal routers. Mounted alongside the bus so the
-    /// router observes the bootstrap `mission_goal` event during initial
-    /// replay and pushes the launch prompt into the lead's stdin.
-    pub routers: Arc<router::RouterRegistry>,
-    /// MCP server lifecycle handle (impl 0013). Unix socket listener
-    /// that external clients connect to via the `runner-mcp` bridge.
-    pub mcp: Arc<mcp::McpHandle>,
-    /// Cross-window coordination map (impl 0018). Tracks which subject
-    /// (mission / direct chat) each window is looking at + when it
-    /// was last focused, so exactly one window owns a duplicated subject's
-    /// PTY.
-    pub windows: Arc<windows::WindowRegistry>,
-    /// Broadcast channel every app-observable event flows through. The
-    /// frontend subscribes and forwards to its own event surface (the
-    /// Tauri layer re-emits to the webview verbatim).
-    pub events: EventChannel,
-    /// The application's user-facing version (the Tauri crate's
-    /// `CARGO_PKG_VERSION`, which the release bump updates). Advertised by
-    /// the MCP server's `ServerInfo`.
-    pub app_version: String,
-}
-
-impl AppCore {
-    /// Session-event sink for spawn/resume/inject call sites. Holds the
-    /// manager as `Weak` because instances get stored inside the manager's
-    /// own session state (codex capture context) — a strong ref would cycle.
-    pub fn session_events(&self) -> CoreSessionEvents {
-        CoreSessionEvents::new(
-            Arc::clone(&self.db),
-            Arc::downgrade(&self.sessions),
-            Arc::clone(&self.windows),
-            self.events.clone(),
-        )
-    }
-
-    /// Broadcast the current window→subject map. Called after every window
-    /// registry mutation so all windows converge on a consistent picture of
-    /// who owns what. Broadcast, not targeted: each window filters by its
-    /// own subject (spec decision 5).
-    pub fn broadcast_focus_map(&self) {
-        self.events
-            .emit("window_focus_map", &self.windows.snapshot());
-    }
-}
+pub mod bootstrap;
+pub mod pane_layout;
+pub mod terminal_ime;
+pub mod terminal_resize;
+pub mod text_util;
diff --git a/crates/runner-native/src/main.rs b/crates/runner-app/src/main.rs
similarity index 92%
rename from crates/runner-native/src/main.rs
rename to crates/runner-app/src/main.rs
index 9158ada..a584cc4 100644
--- a/crates/runner-native/src/main.rs
+++ b/crates/runner-app/src/main.rs
@@ -12,21 +12,21 @@ use gpui::{
     MouseButton, ScrollDelta, ScrollWheelEvent, SharedString, Subscription, TitlebarOptions,
     Window, WindowBounds, WindowOptions,
 };
-use runner_app::model::{Runner, SessionStatus};
-use runner_app::ops::session::DirectSessionEntry;
-use runner_app::AppCore;
-use runner_native::bootstrap::{
+use runner_backend::model::{Runner, SessionStatus};
+use runner_backend::ops::session::DirectSessionEntry;
+use runner_backend::AppCore;
+use runner_app::bootstrap::{
     boot_core, native_paths, stop_running_sessions_on_quit, NativePaths,
 };
-use runner_native::pane_layout::{
+use runner_app::pane_layout::{
     PaneLayout, PaneLeaf, PaneNode, PresetKind, SplitOrientation, TabSet,
 };
-use runner_native::terminal_ime::TerminalInput;
+use runner_app::terminal_ime::TerminalInput;
 use runner_terminal::terminal::{TerminalBridge, TerminalSession};
 
 use terminal_element::TerminalElement;
 
-actions!(runner_native_ui, [Quit, TermPaste, NewTab]);
+actions!(runner_app_ui, [Quit, TermPaste, NewTab]);
 
 mod chat;
 mod panes;
@@ -103,21 +103,21 @@ impl NativeRoot {
         .detach();
 
         let mut errors = Vec::new();
-        let sessions = match runner_app::ops::session::session_list_recent_direct(&core) {
+        let sessions = match runner_backend::ops::session::session_list_recent_direct(&core) {
             Ok(sessions) => sessions,
             Err(error) => {
                 errors.push(error.to_string());
                 Vec::new()
             }
         };
-        let runners = match runner_app::ops::runner::runner_list(&core) {
+        let runners = match runner_backend::ops::runner::runner_list(&core) {
             Ok(runners) => runners,
             Err(error) => {
                 errors.push(error.to_string());
                 Vec::new()
             }
         };
-        let tabs = match runner_app::ops::node::node_list(&core)
+        let tabs = match runner_backend::ops::node::node_list(&core)
             .map_err(anyhow::Error::from)
             .and_then(|rows| TabSet::from_rows(&rows))
         {
@@ -151,14 +151,14 @@ impl NativeRoot {
     }
 
     fn refresh_sessions(&mut self) {
-        match runner_app::ops::session::session_list_recent_direct(&self.core) {
+        match runner_backend::ops::session::session_list_recent_direct(&self.core) {
             Ok(sessions) => self.sessions = sessions,
             Err(error) => self.error = Some(error.to_string()),
         }
     }
 
     fn reload_tabs(&mut self) -> Result<()> {
-        let rows = runner_app::ops::node::node_list(&self.core)?;
+        let rows = runner_backend::ops::node::node_list(&self.core)?;
         self.tabs.replace_rows(&rows)
     }
 
diff --git a/crates/runner-native/src/pane_layout.rs b/crates/runner-app/src/pane_layout.rs
similarity index 99%
rename from crates/runner-native/src/pane_layout.rs
rename to crates/runner-app/src/pane_layout.rs
index 631ae8d..b7bd1fa 100644
--- a/crates/runner-native/src/pane_layout.rs
+++ b/crates/runner-app/src/pane_layout.rs
@@ -1,8 +1,8 @@
 use std::collections::BTreeMap;
 
 use anyhow::{bail, Context as _, Result};
-use runner_app::ops::node::NodeTabUpsertInput;
-use runner_app::repo::node::{NodeRow, NodeType};
+use runner_backend::ops::node::NodeTabUpsertInput;
+use runner_backend::repo::node::{NodeRow, NodeType};
 use serde::{Deserialize, Serialize};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
diff --git a/crates/runner-native/src/panes.rs b/crates/runner-app/src/panes.rs
similarity index 100%
rename from crates/runner-native/src/panes.rs
rename to crates/runner-app/src/panes.rs
diff --git a/crates/runner-native/src/sidebar.rs b/crates/runner-app/src/sidebar.rs
similarity index 100%
rename from crates/runner-native/src/sidebar.rs
rename to crates/runner-app/src/sidebar.rs
diff --git a/crates/runner-native/src/terminal_element.rs b/crates/runner-app/src/terminal_element.rs
similarity index 99%
rename from crates/runner-native/src/terminal_element.rs
rename to crates/runner-app/src/terminal_element.rs
index 54491f2..a6a7595 100644
--- a/crates/runner-native/src/terminal_element.rs
+++ b/crates/runner-app/src/terminal_element.rs
@@ -22,8 +22,8 @@ use gpui::{
     Window,
 };
 
-use runner_native::terminal_ime::TerminalInput;
-use runner_native::terminal_resize::{
+use runner_app::terminal_ime::TerminalInput;
+use runner_app::terminal_resize::{
     size_push_verdict, terminal_grid_size, SizePushVerdict, TerminalGridSize,
 };
 use runner_terminal::palette;
diff --git a/crates/runner-native/src/terminal_ime.rs b/crates/runner-app/src/terminal_ime.rs
similarity index 96%
rename from crates/runner-native/src/terminal_ime.rs
rename to crates/runner-app/src/terminal_ime.rs
index 5e8eca5..c8b011c 100644
--- a/crates/runner-native/src/terminal_ime.rs
+++ b/crates/runner-app/src/terminal_ime.rs
@@ -175,7 +175,7 @@ impl TerminalInput {
         self.write_result.take()
     }
 
-    pub fn commit_text(&mut self, text: &str) -> runner_app::error::Result<()> {
+    pub fn commit_text(&mut self, text: &str) -> runner_backend::error::Result<()> {
         self.composition.clear();
         if text.is_empty() {
             return Ok(());
@@ -185,12 +185,12 @@ impl TerminalInput {
         Ok(())
     }
 
-    fn commit_marked_text(&mut self) -> runner_app::error::Result<()> {
+    fn commit_marked_text(&mut self) -> runner_backend::error::Result<()> {
         let text = self.marked_text().unwrap_or_default().to_owned();
         self.commit_text(&text)
     }
 
-    fn record_write_result(&mut self, result: runner_app::error::Result<()>) {
+    fn record_write_result(&mut self, result: runner_backend::error::Result<()>) {
         self.write_result = Some(result.map_err(|error| error.to_string()));
     }
 }
diff --git a/crates/runner-native/src/terminal_resize.rs b/crates/runner-app/src/terminal_resize.rs
similarity index 100%
rename from crates/runner-native/src/terminal_resize.rs
rename to crates/runner-app/src/terminal_resize.rs
diff --git a/crates/runner-native/src/text_util.rs b/crates/runner-app/src/text_util.rs
similarity index 100%
rename from crates/runner-native/src/text_util.rs
rename to crates/runner-app/src/text_util.rs
diff --git a/crates/runner-native/src/theme.rs b/crates/runner-app/src/theme.rs
similarity index 100%
rename from crates/runner-native/src/theme.rs
rename to crates/runner-app/src/theme.rs
diff --git a/crates/runner-native/tests/pane_layout.rs b/crates/runner-app/tests/pane_layout.rs
similarity index 97%
rename from crates/runner-native/tests/pane_layout.rs
rename to crates/runner-app/tests/pane_layout.rs
index 4de4c0e..49a62ee 100644
--- a/crates/runner-native/tests/pane_layout.rs
+++ b/crates/runner-app/tests/pane_layout.rs
@@ -1,5 +1,5 @@
-use runner_app::repo::node::{NodeRow, NodeType};
-use runner_native::pane_layout::{PaneLayout, PaneNode, PresetKind, SplitOrientation, TabSet};
+use runner_backend::repo::node::{NodeRow, NodeType};
+use runner_app::pane_layout::{PaneLayout, PaneNode, PresetKind, SplitOrientation, TabSet};
 
 fn row(id: &str, position: i64, layout: &PaneLayout) -> NodeRow {
     NodeRow {
diff --git a/crates/runner-native/tests/session_manager_integration.rs b/crates/runner-app/tests/session_manager_integration.rs
similarity index 85%
rename from crates/runner-native/tests/session_manager_integration.rs
rename to crates/runner-app/tests/session_manager_integration.rs
index 0825f7a..aba5457 100644
--- a/crates/runner-native/tests/session_manager_integration.rs
+++ b/crates/runner-app/tests/session_manager_integration.rs
@@ -3,10 +3,10 @@ use std::sync::Arc;
 use std::thread;
 use std::time::{Duration, Instant};
 
-use runner_app::ops::runner::CreateRunnerInput;
-use runner_app::router::runtime::PermissionMode;
-use runner_native::bootstrap::{boot_core, NativePaths};
-use runner_native::terminal_ime::TerminalInput;
+use runner_backend::ops::runner::CreateRunnerInput;
+use runner_backend::router::runtime::PermissionMode;
+use runner_app::bootstrap::{boot_core, NativePaths};
+use runner_app::terminal_ime::TerminalInput;
 use runner_terminal::replay::visible_lines;
 use runner_terminal::terminal::{TerminalBridge, TerminalSession};
 
@@ -30,7 +30,7 @@ fn direct_chat_flows_from_app_core_session_manager_into_terminal_grid() {
     let temp = tempfile::tempdir().unwrap();
     let paths = NativePaths::new(temp.path().join("app-data"), temp.path().join("logs"));
     let core = boot_core(&paths).unwrap();
-    let runner = runner_app::ops::runner::runner_create(
+    let runner = runner_backend::ops::runner::runner_create(
         &core,
         CreateRunnerInput {
             handle: "phase3-seam".into(),
@@ -47,7 +47,7 @@ fn direct_chat_flows_from_app_core_session_manager_into_terminal_grid() {
         },
     )
     .unwrap();
-    let spawned = runner_app::ops::session::session_start_direct(
+    let spawned = runner_backend::ops::session::session_start_direct(
         &core,
         runner.id,
         None,
@@ -69,7 +69,7 @@ fn direct_chat_flows_from_app_core_session_manager_into_terminal_grid() {
     terminal.submit_text("manager-owned-pty").unwrap();
     let rendered = wait_for_text(&terminal, "manager-owned-pty");
 
-    runner_app::ops::session::session_kill(&core, &spawned.id).unwrap();
+    runner_backend::ops::session::session_kill(&core, &spawned.id).unwrap();
     assert!(
         rendered,
         "manager output never reached the alacritty terminal grid"
@@ -81,7 +81,7 @@ fn terminal_ime_commit_forwards_utf8_through_session_manager() {
     let temp = tempfile::tempdir().unwrap();
     let paths = NativePaths::new(temp.path().join("app-data"), temp.path().join("logs"));
     let core = boot_core(&paths).unwrap();
-    let runner = runner_app::ops::runner::runner_create(
+    let runner = runner_backend::ops::runner::runner_create(
         &core,
         CreateRunnerInput {
             handle: "terminal-ime".into(),
@@ -98,7 +98,7 @@ fn terminal_ime_commit_forwards_utf8_through_session_manager() {
         },
     )
     .unwrap();
-    let spawned = runner_app::ops::session::session_start_direct(
+    let spawned = runner_backend::ops::session::session_start_direct(
         &core,
         runner.id,
         None,
@@ -124,7 +124,7 @@ fn terminal_ime_commit_forwards_utf8_through_session_manager() {
         visible_lines(&*term).join("\n")
     };
 
-    runner_app::ops::session::session_kill(&core, &spawned.id).unwrap();
+    runner_backend::ops::session::session_kill(&core, &spawned.id).unwrap();
     assert!(rendered, "committed UTF-8 did not reach the terminal grid");
     assert!(!visible.contains("pinyin"), "marked text reached the PTY");
 }
@@ -134,7 +134,7 @@ fn bridge_keeps_multiple_tab_sessions_attached_with_independent_geometry() {
     let temp = tempfile::tempdir().unwrap();
     let paths = NativePaths::new(temp.path().join("app-data"), temp.path().join("logs"));
     let core = boot_core(&paths).unwrap();
-    let runner = runner_app::ops::runner::runner_create(
+    let runner = runner_backend::ops::runner::runner_create(
         &core,
         CreateRunnerInput {
             handle: "phase4-tabs".into(),
@@ -151,7 +151,7 @@ fn bridge_keeps_multiple_tab_sessions_attached_with_independent_geometry() {
         },
     )
     .unwrap();
-    let first = runner_app::ops::session::session_start_direct(
+    let first = runner_backend::ops::session::session_start_direct(
         &core,
         runner.id.clone(),
         None,
@@ -161,7 +161,7 @@ fn bridge_keeps_multiple_tab_sessions_attached_with_independent_geometry() {
         Some(24),
     )
     .unwrap();
-    let second = runner_app::ops::session::session_start_direct(
+    let second = runner_backend::ops::session::session_start_direct(
         &core,
         runner.id,
         None,
@@ -190,6 +190,6 @@ fn bridge_keeps_multiple_tab_sessions_attached_with_independent_geometry() {
     assert_eq!(first_terminal.size(), (80, 24));
     assert_eq!(second_terminal.size(), (120, 40));
 
-    runner_app::ops::session::session_kill(&core, &first.id).unwrap();
-    runner_app::ops::session::session_kill(&core, &second.id).unwrap();
+    runner_backend::ops::session::session_kill(&core, &first.id).unwrap();
+    runner_backend::ops::session::session_kill(&core, &second.id).unwrap();
 }
diff --git a/crates/runner-native/tests/terminal_ime.rs b/crates/runner-app/tests/terminal_ime.rs
similarity index 96%
rename from crates/runner-native/tests/terminal_ime.rs
rename to crates/runner-app/tests/terminal_ime.rs
index f537539..7f2cc60 100644
--- a/crates/runner-native/tests/terminal_ime.rs
+++ b/crates/runner-app/tests/terminal_ime.rs
@@ -1,4 +1,4 @@
-use runner_native::terminal_ime::{terminal_key_route, TerminalComposition, TerminalKeyRoute};
+use runner_app::terminal_ime::{terminal_key_route, TerminalComposition, TerminalKeyRoute};
 
 #[test]
 fn composition_replaces_and_clears_marked_text_with_utf16_selection_math() {
diff --git a/crates/runner-native/tests/text_util.rs b/crates/runner-app/tests/text_util.rs
similarity index 98%
rename from crates/runner-native/tests/text_util.rs
rename to crates/runner-app/tests/text_util.rs
index 9b8cb1a..b78725d 100644
--- a/crates/runner-native/tests/text_util.rs
+++ b/crates/runner-app/tests/text_util.rs
@@ -2,7 +2,7 @@
 //! selection offsets are relative to the marked string, and cursor
 //! navigation must respect grapheme clusters, not Unicode scalars.
 
-use runner_native::text_util::{
+use runner_app::text_util::{
     marked_selection, next_grapheme_boundary, offset_from_utf16, offset_to_utf16,
     prev_grapheme_boundary, range_from_utf16,
 };
diff --git a/crates/runner-backend/Cargo.toml b/crates/runner-backend/Cargo.toml
new file mode 100644
index 0000000..cf6386f
--- /dev/null
+++ b/crates/runner-backend/Cargo.toml
@@ -0,0 +1,58 @@
+[package]
+name = "runner-backend"
+version = "0.3.17"
+description = "UI-agnostic application core for Runner: command bodies, session manager, event bus, router, and MCP server"
+edition.workspace = true
+authors.workspace = true
+
+[lib]
+name = "runner_backend"
+
+[dependencies]
+runner-core = { path = "../runner-core" }
+log = "0.4"
+serde = { workspace = true }
+serde_json = { workspace = true }
+base64 = "0.22"
+rusqlite = { version = "0.32", features = ["bundled", "chrono", "serde_json"] }
+# Derived row<->struct mapping for the repo layer (impl 0021). 0.36.x is
+# the release whose rusqlite dependency is 0.32, matching the workspace
+# rusqlite exactly so the Row types unify.
+serde_rusqlite = "0.36"
+r2d2 = "0.8"
+r2d2_sqlite = "0.25"
+chrono = { workspace = true }
+thiserror = { workspace = true }
+ulid = { workspace = true }
+uuid = { workspace = true }
+# Regular dep (not dev-only) because the sidecar writer needs
+# NamedTempFile::persist for a Windows-safe atomic replace.
+tempfile = "3"
+# Filesystem watcher for the per-mission event-log tail (C7). The
+# `macos_fsevent` backend is the default on macOS; on Linux it falls back to
+# inotify, on Windows to ReadDirectoryChangesW.
+notify = "6"
+# MCP server (impl 0013): Unix socket listener for external clients.
+# The `runner-mcp` sidecar bridges stdio ↔ this socket.
+rmcp = { version = "1.7", features = ["server"] }
+schemars = "1"
+tokio = { version = "1", features = ["net", "rt", "io-util", "sync"] }
+tokio-util = { version = "0.7", features = ["rt"] }
+# Codex MCP config lives in ~/.codex/config.toml; toml_edit preserves
+# user-authored comments + formatting on round-trip writes.
+toml_edit = "0.25"
+
+# Unix-only deps:
+#  - libc: FIFO mkfifo + poll() inside session::tmux_runtime.
+#  - portable-pty: backing crate for session::pty_runtime, the
+#    in-process replacement for tmux (impl 0011). Windows keeps the
+#    tmux fallback until a named-pipe equivalent lands.
+[target.'cfg(unix)'.dependencies]
+libc = "0.2"
+portable-pty = "0.9"
+
+[dev-dependencies]
+# Used by issue #124's forwarder-contention regression test to hold the
+# event-log flock from a second fd; matches the version `runner-core`
+# pulls in transitively so the trait impl resolves identically.
+fs2 = "0.4"
diff --git a/crates/runner-app/migrations/0001_init.sql b/crates/runner-backend/migrations/0001_init.sql
similarity index 100%
rename from crates/runner-app/migrations/0001_init.sql
rename to crates/runner-backend/migrations/0001_init.sql
diff --git a/crates/runner-app/migrations/0002_persona_only_seeds.sql b/crates/runner-backend/migrations/0002_persona_only_seeds.sql
similarity index 100%
rename from crates/runner-app/migrations/0002_persona_only_seeds.sql
rename to crates/runner-backend/migrations/0002_persona_only_seeds.sql
diff --git a/crates/runner-app/migrations/0003_session_runtime.sql b/crates/runner-backend/migrations/0003_session_runtime.sql
similarity index 100%
rename from crates/runner-app/migrations/0003_session_runtime.sql
rename to crates/runner-backend/migrations/0003_session_runtime.sql
diff --git a/crates/runner-app/migrations/0004_mission_archived_at.sql b/crates/runner-backend/migrations/0004_mission_archived_at.sql
similarity index 100%
rename from crates/runner-app/migrations/0004_mission_archived_at.sql
rename to crates/runner-backend/migrations/0004_mission_archived_at.sql
diff --git a/crates/runner-app/migrations/0005_crew_system_prompt_addendum.sql b/crates/runner-backend/migrations/0005_crew_system_prompt_addendum.sql
similarity index 100%
rename from crates/runner-app/migrations/0005_crew_system_prompt_addendum.sql
rename to crates/runner-backend/migrations/0005_crew_system_prompt_addendum.sql
diff --git a/crates/runner-app/migrations/0006_drop_crews_signal_types.sql b/crates/runner-backend/migrations/0006_drop_crews_signal_types.sql
similarity index 100%
rename from crates/runner-app/migrations/0006_drop_crews_signal_types.sql
rename to crates/runner-backend/migrations/0006_drop_crews_signal_types.sql
diff --git a/crates/runner-app/migrations/0007_direct_runtime_sessions.sql b/crates/runner-backend/migrations/0007_direct_runtime_sessions.sql
similarity index 100%
rename from crates/runner-app/migrations/0007_direct_runtime_sessions.sql
rename to crates/runner-backend/migrations/0007_direct_runtime_sessions.sql
diff --git a/crates/runner-app/migrations/0008_drop_crews_orchestrator_policy.sql b/crates/runner-backend/migrations/0008_drop_crews_orchestrator_policy.sql
similarity index 100%
rename from crates/runner-app/migrations/0008_drop_crews_orchestrator_policy.sql
rename to crates/runner-backend/migrations/0008_drop_crews_orchestrator_policy.sql
diff --git a/crates/runner-app/migrations/0009_folders_tabs.sql b/crates/runner-backend/migrations/0009_folders_tabs.sql
similarity index 100%
rename from crates/runner-app/migrations/0009_folders_tabs.sql
rename to crates/runner-backend/migrations/0009_folders_tabs.sql
diff --git a/crates/runner-app/migrations/0010_tab_attention.sql b/crates/runner-backend/migrations/0010_tab_attention.sql
similarity index 100%
rename from crates/runner-app/migrations/0010_tab_attention.sql
rename to crates/runner-backend/migrations/0010_tab_attention.sql
diff --git a/crates/runner-app/migrations/0011_projects.sql b/crates/runner-backend/migrations/0011_projects.sql
similarity index 100%
rename from crates/runner-app/migrations/0011_projects.sql
rename to crates/runner-backend/migrations/0011_projects.sql
diff --git a/crates/runner-app/migrations/0012_drop_collapsed_view_state.sql b/crates/runner-backend/migrations/0012_drop_collapsed_view_state.sql
similarity index 100%
rename from crates/runner-app/migrations/0012_drop_collapsed_view_state.sql
rename to crates/runner-backend/migrations/0012_drop_collapsed_view_state.sql
diff --git a/crates/runner-app/migrations/0013_slot_runtime_override.sql b/crates/runner-backend/migrations/0013_slot_runtime_override.sql
similarity index 100%
rename from crates/runner-app/migrations/0013_slot_runtime_override.sql
rename to crates/runner-backend/migrations/0013_slot_runtime_override.sql
diff --git a/crates/runner-app/migrations/0014_nodes.sql b/crates/runner-backend/migrations/0014_nodes.sql
similarity index 100%
rename from crates/runner-app/migrations/0014_nodes.sql
rename to crates/runner-backend/migrations/0014_nodes.sql
diff --git a/crates/runner-app/migrations/0015_retire_folders.sql b/crates/runner-backend/migrations/0015_retire_folders.sql
similarity index 100%
rename from crates/runner-app/migrations/0015_retire_folders.sql
rename to crates/runner-backend/migrations/0015_retire_folders.sql
diff --git a/crates/runner-app/migrations/0016_session_last_size.sql b/crates/runner-backend/migrations/0016_session_last_size.sql
similarity index 100%
rename from crates/runner-app/migrations/0016_session_last_size.sql
rename to crates/runner-backend/migrations/0016_session_last_size.sql
diff --git a/crates/runner-app/migrations/0017_session_resume_on_launch.sql b/crates/runner-backend/migrations/0017_session_resume_on_launch.sql
similarity index 100%
rename from crates/runner-app/migrations/0017_session_resume_on_launch.sql
rename to crates/runner-backend/migrations/0017_session_resume_on_launch.sql
diff --git a/crates/runner-app/migrations/0018_slot_model_override.sql b/crates/runner-backend/migrations/0018_slot_model_override.sql
similarity index 100%
rename from crates/runner-app/migrations/0018_slot_model_override.sql
rename to crates/runner-backend/migrations/0018_slot_model_override.sql
diff --git a/crates/runner-app/migrations/0019_session_agent_options.sql b/crates/runner-backend/migrations/0019_session_agent_options.sql
similarity index 100%
rename from crates/runner-app/migrations/0019_session_agent_options.sql
rename to crates/runner-backend/migrations/0019_session_agent_options.sql
diff --git a/crates/runner-app/migrations/0020_slot_effort_override.sql b/crates/runner-backend/migrations/0020_slot_effort_override.sql
similarity index 100%
rename from crates/runner-app/migrations/0020_slot_effort_override.sql
rename to crates/runner-backend/migrations/0020_slot_effort_override.sql
diff --git a/crates/runner-app/src/cli_install.rs b/crates/runner-backend/src/cli_install.rs
similarity index 100%
rename from crates/runner-app/src/cli_install.rs
rename to crates/runner-backend/src/cli_install.rs
diff --git a/crates/runner-app/src/db.rs b/crates/runner-backend/src/db.rs
similarity index 100%
rename from crates/runner-app/src/db.rs
rename to crates/runner-backend/src/db.rs
diff --git a/crates/runner-app/src/error.rs b/crates/runner-backend/src/error.rs
similarity index 100%
rename from crates/runner-app/src/error.rs
rename to crates/runner-backend/src/error.rs
diff --git a/crates/runner-app/src/event_bus/mod.rs b/crates/runner-backend/src/event_bus/mod.rs
similarity index 100%
rename from crates/runner-app/src/event_bus/mod.rs
rename to crates/runner-backend/src/event_bus/mod.rs
diff --git a/crates/runner-app/src/events.rs b/crates/runner-backend/src/events.rs
similarity index 100%
rename from crates/runner-app/src/events.rs
rename to crates/runner-backend/src/events.rs
diff --git a/crates/runner-backend/src/lib.rs b/crates/runner-backend/src/lib.rs
new file mode 100644
index 0000000..e806645
--- /dev/null
+++ b/crates/runner-backend/src/lib.rs
@@ -0,0 +1,91 @@
+// Runner's UI-agnostic application core (impl 0031 Phase 2).
+//
+// Everything a frontend needs to run Runner lives here: the SQLite layer,
+// the PTY session manager, the per-mission event bus + signal router, the
+// MCP server, and the command bodies (`ops`). Frontends — the Tauri app
+// today, the native GPUI binary in Phase 3 — are thin adapters: they build
+// an `AppCore`, subscribe to its event channel, and delegate their command
+// surface to `ops::*`.
+
+pub mod cli_install;
+pub mod db;
+pub mod error;
+pub mod event_bus;
+pub mod events;
+pub mod mcp;
+pub mod model;
+pub mod ops;
+pub mod repo;
+pub mod router;
+pub mod session;
+pub mod shell_path;
+pub mod windows;
+
+use std::path::PathBuf;
+use std::sync::Arc;
+
+use events::EventChannel;
+use session::manager::CoreSessionEvents;
+
+/// Shared application state. One instance per process, cheap to clone
+/// (every field is an `Arc` or small value) — the Tauri layer stores it in
+/// `app.manage`, the MCP handler clones it per connection.
+#[derive(Clone)]
+pub struct AppCore {
+    pub db: Arc<db::DbPool>,
+    /// Root of the app's per-user data tree — `$APPDATA/runner/` on real
+    /// installs, a tempdir in tests. Mission commands resolve event-log paths
+    /// relative to this via `runner_core::event_log::path`.
+    pub app_data_dir: PathBuf,
+    /// Live per-mission session manager. Created at app
+    /// start, shared across all frontends and the per-session
+    /// forwarder threads it spawns.
+    pub sessions: Arc<session::SessionManager>,
+    /// Live per-mission event-bus watchers. Mounted by `mission_start` once
+    /// the opening events are durable; unmounted by `mission_stop` and on
+    /// any rollback path.
+    pub buses: Arc<event_bus::BusRegistry>,
+    /// Live per-mission signal routers. Mounted alongside the bus so the
+    /// router observes the bootstrap `mission_goal` event during initial
+    /// replay and pushes the launch prompt into the lead's stdin.
+    pub routers: Arc<router::RouterRegistry>,
+    /// MCP server lifecycle handle (impl 0013). Unix socket listener
+    /// that external clients connect to via the `runner-mcp` bridge.
+    pub mcp: Arc<mcp::McpHandle>,
+    /// Cross-window coordination map (impl 0018). Tracks which subject
+    /// (mission / direct chat) each window is looking at + when it
+    /// was last focused, so exactly one window owns a duplicated subject's
+    /// PTY.
+    pub windows: Arc<windows::WindowRegistry>,
+    /// Broadcast channel every app-observable event flows through. The
+    /// frontend subscribes and forwards to its own event surface (the
+    /// Tauri layer re-emits to the webview verbatim).
+    pub events: EventChannel,
+    /// The application's user-facing version (the Tauri crate's
+    /// `CARGO_PKG_VERSION`, which the release bump updates). Advertised by
+    /// the MCP server's `ServerInfo`.
+    pub app_version: String,
+}
+
+impl AppCore {
+    /// Session-event sink for spawn/resume/inject call sites. Holds the
+    /// manager as `Weak` because instances get stored inside the manager's
+    /// own session state (codex capture context) — a strong ref would cycle.
+    pub fn session_events(&self) -> CoreSessionEvents {
+        CoreSessionEvents::new(
+            Arc::clone(&self.db),
+            Arc::downgrade(&self.sessions),
+            Arc::clone(&self.windows),
+            self.events.clone(),
+        )
+    }
+
+    /// Broadcast the current window→subject map. Called after every window
+    /// registry mutation so all windows converge on a consistent picture of
+    /// who owns what. Broadcast, not targeted: each window filters by its
+    /// own subject (spec decision 5).
+    pub fn broadcast_focus_map(&self) {
+        self.events
+            .emit("window_focus_map", &self.windows.snapshot());
+    }
+}
diff --git a/crates/runner-app/src/mcp/mod.rs b/crates/runner-backend/src/mcp/mod.rs
similarity index 100%
rename from crates/runner-app/src/mcp/mod.rs
rename to crates/runner-backend/src/mcp/mod.rs
diff --git a/crates/runner-app/src/mcp/server.rs b/crates/runner-backend/src/mcp/server.rs
similarity index 100%
rename from crates/runner-app/src/mcp/server.rs
rename to crates/runner-backend/src/mcp/server.rs
diff --git a/crates/runner-app/src/mcp/tools/crew.rs b/crates/runner-backend/src/mcp/tools/crew.rs
similarity index 100%
rename from crates/runner-app/src/mcp/tools/crew.rs
rename to crates/runner-backend/src/mcp/tools/crew.rs
diff --git a/crates/runner-app/src/mcp/tools/mission.rs b/crates/runner-backend/src/mcp/tools/mission.rs
similarity index 100%
rename from crates/runner-app/src/mcp/tools/mission.rs
rename to crates/runner-backend/src/mcp/tools/mission.rs
diff --git a/crates/runner-app/src/mcp/tools/mod.rs b/crates/runner-backend/src/mcp/tools/mod.rs
similarity index 100%
rename from crates/runner-app/src/mcp/tools/mod.rs
rename to crates/runner-backend/src/mcp/tools/mod.rs
diff --git a/crates/runner-app/src/mcp/tools/project.rs b/crates/runner-backend/src/mcp/tools/project.rs
similarity index 100%
rename from crates/runner-app/src/mcp/tools/project.rs
rename to crates/runner-backend/src/mcp/tools/project.rs
diff --git a/crates/runner-app/src/mcp/tools/runner.rs b/crates/runner-backend/src/mcp/tools/runner.rs
similarity index 100%
rename from crates/runner-app/src/mcp/tools/runner.rs
rename to crates/runner-backend/src/mcp/tools/runner.rs
diff --git a/crates/runner-app/src/mcp/tools/session.rs b/crates/runner-backend/src/mcp/tools/session.rs
similarity index 100%
rename from crates/runner-app/src/mcp/tools/session.rs
rename to crates/runner-backend/src/mcp/tools/session.rs
diff --git a/crates/runner-app/src/mcp/tools/slot.rs b/crates/runner-backend/src/mcp/tools/slot.rs
similarity index 100%
rename from crates/runner-app/src/mcp/tools/slot.rs
rename to crates/runner-backend/src/mcp/tools/slot.rs
diff --git a/crates/runner-app/src/model.rs b/crates/runner-backend/src/model.rs
similarity index 100%
rename from crates/runner-app/src/model.rs
rename to crates/runner-backend/src/model.rs
diff --git a/crates/runner-app/src/ops/crew.rs b/crates/runner-backend/src/ops/crew.rs
similarity index 100%
rename from crates/runner-app/src/ops/crew.rs
rename to crates/runner-backend/src/ops/crew.rs
diff --git a/crates/runner-app/src/ops/mcp.rs b/crates/runner-backend/src/ops/mcp.rs
similarity index 100%
rename from crates/runner-app/src/ops/mcp.rs
rename to crates/runner-backend/src/ops/mcp.rs
diff --git a/crates/runner-app/src/ops/mission.rs b/crates/runner-backend/src/ops/mission.rs
similarity index 100%
rename from crates/runner-app/src/ops/mission.rs
rename to crates/runner-backend/src/ops/mission.rs
diff --git a/crates/runner-app/src/ops/mod.rs b/crates/runner-backend/src/ops/mod.rs
similarity index 100%
rename from crates/runner-app/src/ops/mod.rs
rename to crates/runner-backend/src/ops/mod.rs
diff --git a/crates/runner-app/src/ops/node.rs b/crates/runner-backend/src/ops/node.rs
similarity index 100%
rename from crates/runner-app/src/ops/node.rs
rename to crates/runner-backend/src/ops/node.rs
diff --git a/crates/runner-app/src/ops/project.rs b/crates/runner-backend/src/ops/project.rs
similarity index 100%
rename from crates/runner-app/src/ops/project.rs
rename to crates/runner-backend/src/ops/project.rs
diff --git a/crates/runner-app/src/ops/runner.rs b/crates/runner-backend/src/ops/runner.rs
similarity index 100%
rename from crates/runner-app/src/ops/runner.rs
rename to crates/runner-backend/src/ops/runner.rs
diff --git a/crates/runner-app/src/ops/runtime.rs b/crates/runner-backend/src/ops/runtime.rs
similarity index 100%
rename from crates/runner-app/src/ops/runtime.rs
rename to crates/runner-backend/src/ops/runtime.rs
diff --git a/crates/runner-app/src/ops/session.rs b/crates/runner-backend/src/ops/session.rs
similarity index 100%
rename from crates/runner-app/src/ops/session.rs
rename to crates/runner-backend/src/ops/session.rs
diff --git a/crates/runner-app/src/ops/slot.rs b/crates/runner-backend/src/ops/slot.rs
similarity index 100%
rename from crates/runner-app/src/ops/slot.rs
rename to crates/runner-backend/src/ops/slot.rs
diff --git a/crates/runner-app/src/repo/crew.rs b/crates/runner-backend/src/repo/crew.rs
similarity index 100%
rename from crates/runner-app/src/repo/crew.rs
rename to crates/runner-backend/src/repo/crew.rs
diff --git a/crates/runner-app/src/repo/mission.rs b/crates/runner-backend/src/repo/mission.rs
similarity index 100%
rename from crates/runner-app/src/repo/mission.rs
rename to crates/runner-backend/src/repo/mission.rs
diff --git a/crates/runner-app/src/repo/mod.rs b/crates/runner-backend/src/repo/mod.rs
similarity index 100%
rename from crates/runner-app/src/repo/mod.rs
rename to crates/runner-backend/src/repo/mod.rs
diff --git a/crates/runner-app/src/repo/node.rs b/crates/runner-backend/src/repo/node.rs
similarity index 100%
rename from crates/runner-app/src/repo/node.rs
rename to crates/runner-backend/src/repo/node.rs
diff --git a/crates/runner-app/src/repo/project.rs b/crates/runner-backend/src/repo/project.rs
similarity index 100%
rename from crates/runner-app/src/repo/project.rs
rename to crates/runner-backend/src/repo/project.rs
diff --git a/crates/runner-app/src/repo/runner.rs b/crates/runner-backend/src/repo/runner.rs
similarity index 100%
rename from crates/runner-app/src/repo/runner.rs
rename to crates/runner-backend/src/repo/runner.rs
diff --git a/crates/runner-app/src/repo/serde.rs b/crates/runner-backend/src/repo/serde.rs
similarity index 100%
rename from crates/runner-app/src/repo/serde.rs
rename to crates/runner-backend/src/repo/serde.rs
diff --git a/crates/runner-app/src/repo/session.rs b/crates/runner-backend/src/repo/session.rs
similarity index 100%
rename from crates/runner-app/src/repo/session.rs
rename to crates/runner-backend/src/repo/session.rs
diff --git a/crates/runner-app/src/repo/slot.rs b/crates/runner-backend/src/repo/slot.rs
similarity index 100%
rename from crates/runner-app/src/repo/slot.rs
rename to crates/runner-backend/src/repo/slot.rs
diff --git a/crates/runner-app/src/router/handlers.rs b/crates/runner-backend/src/router/handlers.rs
similarity index 100%
rename from crates/runner-app/src/router/handlers.rs
rename to crates/runner-backend/src/router/handlers.rs
diff --git a/crates/runner-app/src/router/mod.rs b/crates/runner-backend/src/router/mod.rs
similarity index 100%
rename from crates/runner-app/src/router/mod.rs
rename to crates/runner-backend/src/router/mod.rs
diff --git a/crates/runner-app/src/router/prompt.rs b/crates/runner-backend/src/router/prompt.rs
similarity index 100%
rename from crates/runner-app/src/router/prompt.rs
rename to crates/runner-backend/src/router/prompt.rs
diff --git a/crates/runner-app/src/router/runtime.rs b/crates/runner-backend/src/router/runtime.rs
similarity index 100%
rename from crates/runner-app/src/router/runtime.rs
rename to crates/runner-backend/src/router/runtime.rs
diff --git a/crates/runner-app/src/router/tests.rs b/crates/runner-backend/src/router/tests.rs
similarity index 100%
rename from crates/runner-app/src/router/tests.rs
rename to crates/runner-backend/src/router/tests.rs
diff --git a/crates/runner-app/src/session/codex_capture.rs b/crates/runner-backend/src/session/codex_capture.rs
similarity index 100%
rename from crates/runner-app/src/session/codex_capture.rs
rename to crates/runner-backend/src/session/codex_capture.rs
diff --git a/crates/runner-app/src/session/launch.rs b/crates/runner-backend/src/session/launch.rs
similarity index 100%
rename from crates/runner-app/src/session/launch.rs
rename to crates/runner-backend/src/session/launch.rs
diff --git a/crates/runner-app/src/session/manager/lifecycle.rs b/crates/runner-backend/src/session/manager/lifecycle.rs
similarity index 100%
rename from crates/runner-app/src/session/manager/lifecycle.rs
rename to crates/runner-backend/src/session/manager/lifecycle.rs
diff --git a/crates/runner-app/src/session/manager/mod.rs b/crates/runner-backend/src/session/manager/mod.rs
similarity index 100%
rename from crates/runner-app/src/session/manager/mod.rs
rename to crates/runner-backend/src/session/manager/mod.rs
diff --git a/crates/runner-app/src/session/manager/output.rs b/crates/runner-backend/src/session/manager/output.rs
similarity index 100%
rename from crates/runner-app/src/session/manager/output.rs
rename to crates/runner-backend/src/session/manager/output.rs
diff --git a/crates/runner-app/src/session/manager/spawn.rs b/crates/runner-backend/src/session/manager/spawn.rs
similarity index 100%
rename from crates/runner-app/src/session/manager/spawn.rs
rename to crates/runner-backend/src/session/manager/spawn.rs
diff --git a/crates/runner-app/src/session/manager/tests.rs b/crates/runner-backend/src/session/manager/tests.rs
similarity index 100%
rename from crates/runner-app/src/session/manager/tests.rs
rename to crates/runner-backend/src/session/manager/tests.rs
diff --git a/crates/runner-app/src/session/mod.rs b/crates/runner-backend/src/session/mod.rs
similarity index 100%
rename from crates/runner-app/src/session/mod.rs
rename to crates/runner-backend/src/session/mod.rs
diff --git a/crates/runner-app/src/session/pty_runtime.rs b/crates/runner-backend/src/session/pty_runtime.rs
similarity index 100%
rename from crates/runner-app/src/session/pty_runtime.rs
rename to crates/runner-backend/src/session/pty_runtime.rs
diff --git a/crates/runner-app/src/session/runtime.rs b/crates/runner-backend/src/session/runtime.rs
similarity index 100%
rename from crates/runner-app/src/session/runtime.rs
rename to crates/runner-backend/src/session/runtime.rs
diff --git a/crates/runner-app/src/shell_path.rs b/crates/runner-backend/src/shell_path.rs
similarity index 100%
rename from crates/runner-app/src/shell_path.rs
rename to crates/runner-backend/src/shell_path.rs
diff --git a/crates/runner-app/src/windows.rs b/crates/runner-backend/src/windows.rs
similarity index 100%
rename from crates/runner-app/src/windows.rs
rename to crates/runner-backend/src/windows.rs
diff --git a/crates/runner-native/Cargo.toml b/crates/runner-native/Cargo.toml
deleted file mode 100644
index 7ee37f0..0000000
--- a/crates/runner-native/Cargo.toml
+++ /dev/null
@@ -1,27 +0,0 @@
-[package]
-name = "runner-native"
-version = "0.3.17"
-edition.workspace = true
-authors.workspace = true
-publish = false
-default-run = "runner-native"
-
-[[bin]]
-name = "runner-native"
-path = "src/main.rs"
-
-[dependencies]
-alacritty_terminal = "0.26"
-anyhow = "1"
-base64 = "0.22"
-futures = "0.3"
-gpui = { package = "gpui-ce", version = "0.3" }
-runner-app = { path = "../runner-app" }
-runner-terminal = { path = "../runner-terminal" }
-serde.workspace = true
-serde_json.workspace = true
-tokio = { version = "1", features = ["sync"] }
-unicode-segmentation = "1"
-
-[dev-dependencies]
-tempfile = "3"
diff --git a/crates/runner-native/src/lib.rs b/crates/runner-native/src/lib.rs
deleted file mode 100644
index 1ba78fe..0000000
--- a/crates/runner-native/src/lib.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-pub mod bootstrap;
-pub mod pane_layout;
-pub mod terminal_ime;
-pub mod terminal_resize;
-pub mod text_util;
diff --git a/crates/runner-terminal/Cargo.toml b/crates/runner-terminal/Cargo.toml
index d96a303..e7cb8a7 100644
--- a/crates/runner-terminal/Cargo.toml
+++ b/crates/runner-terminal/Cargo.toml
@@ -9,7 +9,7 @@ publish = false
 alacritty_terminal = "0.26"
 anyhow = "1"
 base64 = "0.22"
-runner-app = { path = "../runner-app" }
+runner-backend = { path = "../runner-backend" }
 serde.workspace = true
 serde_json.workspace = true
 tokio = { version = "1", features = ["sync"] }
diff --git a/crates/runner-terminal/src/lib.rs b/crates/runner-terminal/src/lib.rs
index 1c8e428..cafa11f 100644
--- a/crates/runner-terminal/src/lib.rs
+++ b/crates/runner-terminal/src/lib.rs
@@ -1,10 +1,10 @@
 //! UI-agnostic terminal model for Runner's native app — the `terminal`
 //! half of the Zed-style `terminal` / `terminal_view` split (impl 0046
 //! Workstream C). Owns the `alacritty_terminal` state, parsing, input
-//! encoding, and the fixture corpus; rendering lives in `runner-native`.
+//! encoding, and the fixture corpus; rendering lives in `runner-app`.
 //!
 //! Deliberate deviation from Zed: this crate does not own the PTY.
-//! `runner_app`'s `SessionManager` spawns and manages sessions; this
+//! `runner_backend`'s `SessionManager` spawns and manages sessions; this
 //! crate consumes its output events and produces renderable grid state
 //! plus encoded input bytes.
 
diff --git a/crates/runner-terminal/src/terminal.rs b/crates/runner-terminal/src/terminal.rs
index 3db9a90..3810903 100644
--- a/crates/runner-terminal/src/terminal.rs
+++ b/crates/runner-terminal/src/terminal.rs
@@ -13,9 +13,9 @@ use alacritty_terminal::vte::ansi::Processor;
 use anyhow::{Context as _, Result};
 use base64::engine::general_purpose::STANDARD as B64;
 use base64::Engine as _;
-use runner_app::events::AppEvent;
-use runner_app::session::manager::OutputEvent;
-use runner_app::AppCore;
+use runner_backend::events::AppEvent;
+use runner_backend::session::manager::OutputEvent;
+use runner_backend::AppCore;
 use tokio::sync::broadcast::error::RecvError;
 
 use crate::palette;
@@ -198,12 +198,12 @@ impl TerminalSession {
         Ok(())
     }
 
-    pub fn submit_text(&self, text: &str) -> runner_app::error::Result<()> {
+    pub fn submit_text(&self, text: &str) -> runner_backend::error::Result<()> {
         self.write_user_bytes(text.as_bytes())?;
         self.write_user_bytes(b"\r")
     }
 
-    pub fn write_user_bytes(&self, bytes: &[u8]) -> runner_app::error::Result<()> {
+    pub fn write_user_bytes(&self, bytes: &[u8]) -> runner_backend::error::Result<()> {
         self.core
             .sessions
             .inject_direct_stdin(&self.session_id, bytes, &self.core.session_events())
@@ -215,7 +215,7 @@ impl TerminalSession {
         ctrl: bool,
         alt: bool,
         key_char: Option<&str>,
-    ) -> runner_app::error::Result<bool> {
+    ) -> runner_backend::error::Result<bool> {
         let app_cursor = self
             .term
             .lock_unfair()
@@ -230,7 +230,7 @@ impl TerminalSession {
         }
     }
 
-    pub fn paste(&self, text: &str) -> runner_app::error::Result<()> {
+    pub fn paste(&self, text: &str) -> runner_backend::error::Result<()> {
         let bracketed = self
             .term
             .lock_unfair()
@@ -249,7 +249,7 @@ impl TerminalSession {
             }
             *size = (cols, rows);
         }
-        let _ = runner_app::ops::session::session_resize(&self.core, &self.session_id, cols, rows);
+        let _ = runner_backend::ops::session::session_resize(&self.core, &self.session_id, cols, rows);
         self.term
             .lock()
             .resize(TermSize::new(cols as usize, rows as usize));
@@ -317,7 +317,7 @@ impl TerminalBridge {
             .lock()
             .unwrap()
             .insert(session_id.clone(), Arc::downgrade(&session));
-        let snapshot = runner_app::ops::session::session_output_snapshot(&self.core, &session_id)
+        let snapshot = runner_backend::ops::session::session_output_snapshot(&self.core, &session_id)
             .context("load terminal output snapshot")?;
         session.feed_snapshot_locked(&snapshot)?;
         Ok(())
@@ -370,7 +370,7 @@ impl TerminalBridge {
         for session in sessions {
             let _feed = session.feed_gate.lock().unwrap();
             if let Ok(snapshot) =
-                runner_app::ops::session::session_output_snapshot(&self.core, session.session_id())
+                runner_backend::ops::session::session_output_snapshot(&self.core, session.session_id())
             {
                 let _ = session.feed_snapshot_locked(&snapshot);
             }
@@ -388,34 +388,34 @@ mod tests {
 
     use base64::engine::general_purpose::STANDARD as B64;
     use base64::Engine as _;
-    use runner_app::session::manager::OutputEvent;
+    use runner_backend::session::manager::OutputEvent;
 
     use super::TerminalSession;
     use crate::replay::visible_lines;
-    use runner_app::AppCore;
+    use runner_backend::AppCore;
 
     /// Minimal `AppCore` over a temp dir — the pieces `boot_core` wires
-    /// in runner-native, minus login-shell discovery and startup cleanup.
+    /// in runner-app, minus login-shell discovery and startup cleanup.
     fn test_core(root: &std::path::Path) -> AppCore {
         let app_data_dir = root.join("app-data");
         std::fs::create_dir_all(&app_data_dir).unwrap();
-        let pool = Arc::new(runner_app::db::open_pool(&app_data_dir.join("runner.db")).unwrap());
-        let runtime: Arc<dyn runner_app::session::runtime::SessionRuntime> =
-            Arc::new(runner_app::session::pty_runtime::PtyRuntime::new());
-        let windows = Arc::new(runner_app::windows::WindowRegistry::new());
+        let pool = Arc::new(runner_backend::db::open_pool(&app_data_dir.join("runner.db")).unwrap());
+        let runtime: Arc<dyn runner_backend::session::runtime::SessionRuntime> =
+            Arc::new(runner_backend::session::pty_runtime::PtyRuntime::new());
+        let windows = Arc::new(runner_backend::windows::WindowRegistry::new());
         windows.register("main");
         AppCore {
             db: pool,
             app_data_dir,
-            sessions: runner_app::session::SessionManager::new(
-                runner_app::shell_path::LoginShellEnv::default(),
+            sessions: runner_backend::session::SessionManager::new(
+                runner_backend::shell_path::LoginShellEnv::default(),
                 runtime,
             ),
-            buses: runner_app::event_bus::BusRegistry::new(),
-            routers: runner_app::router::RouterRegistry::new(),
-            mcp: Arc::new(runner_app::mcp::McpHandle::new()),
+            buses: runner_backend::event_bus::BusRegistry::new(),
+            routers: runner_backend::router::RouterRegistry::new(),
+            mcp: Arc::new(runner_backend::mcp::McpHandle::new()),
             windows,
-            events: runner_app::events::EventChannel::new(),
+            events: runner_backend::events::EventChannel::new(),
             app_version: "0.0.0-test".into(),
         }
     }
diff --git a/docs/impls/gpui-rewrite/README.md b/docs/impls/gpui-rewrite/README.md
index 50a59b6..420f805 100644
--- a/docs/impls/gpui-rewrite/README.md
+++ b/docs/impls/gpui-rewrite/README.md
@@ -10,4 +10,4 @@ Standing decisions (dated in the plan):
 - `main` owns product design and the domain model; repo-and-below stays verbatim-identical, migration numbers are allocated on `main` only (plan §Decisions).
 - Framework: `gpui-ce`; terminal architecture mirrors Zed's `terminal`/`terminal_view` split on upstream `alacritty_terminal` (plan §Framework, §Workstream C). Zed's terminal crates are GPL — architectural reference only.
 - Pulse (`~/repos/yicheng47/pulse`) is the window-level UI reference and the updater reference — Sparkle via the pulse pattern (plan §UI reference, §Phase 5).
-- Crate renames after the M3 session-hardening slice (timing revised 2026-08-18): `runner-app` → `runner-backend`, `runner-native` → `runner-app` (plan §Decisions).
+- Crate renames after the M3 session-hardening slice (landed 2026-08-18): `runner-app` → `runner-backend`, `runner-native` → `runner-app` (plan §Decisions).
diff --git a/docs/impls/gpui-rewrite/impl_log.md b/docs/impls/gpui-rewrite/impl_log.md
index 9cd71dc..f60dbdd 100644
--- a/docs/impls/gpui-rewrite/impl_log.md
+++ b/docs/impls/gpui-rewrite/impl_log.md
@@ -6,7 +6,7 @@ Progress record for the whole gpui-rewrite program ([README](README.md)), from t
 
 - **Branch**: `gpui-nightly` (M0+M1 merged via PR #407, M2 via PR #408, both 2026-08-17; M3.1 via PR #409, M3.2 via PR #410, M3.3 via PR #411, M3.4 via the `feat/0046-m3-input-latch` PR, all 2026-08-18). Session-hardening slice complete.
 - **Done**: 0046 M0 (gpui-ce swap), M1 (repo-and-below at `main` parity, node tree adopted, protocol crates wholesale; human-verified 2026-08-17), M2 (terminal split + shell modularization), M3.1–M3.4 (session-hardening slice: reaping, resume seams + geometry, resize storms + owner gating, input latch + quit stamping), terminal-pane IME (M4 pull-forward; Pinyin human-verified 2026-08-18), direct-chat composer removal (parity restore, smoke-tested 2026-08-18).
-- **Next**: crate renames as one mechanical commit (plan decision 7: `runner-app` → `runner-backend`, `runner-native` → `runner-app`); then M3.5 (runtimes slice: discovery, Qoder/TRAE, model catalog, model/effort overrides, codex trust preseed) → start-chat modal + pane controls (M4 pull-forward: `main`'s `StartChatModal` + pane close button replacing the sidebar-swap flow; needs M3.5's backend) → remaining M3 slices → M4 (UI parity) → nightly channel (plan decision 10) → M5 (sweep + watermark). Parity references are `main`'s React frontend (`src/`) and the `design/*.pen` files via the pencil MCP.
+- **Next**: M3.5 (runtimes slice: discovery, Qoder/TRAE, model catalog, model/effort overrides, codex trust preseed) → start-chat modal + pane controls (M4 pull-forward: `main`'s `StartChatModal` + pane close button replacing the sidebar-swap flow; needs M3.5's backend) → remaining M3 slices → M4 (UI parity) → nightly channel (plan decision 10) → M5 (sweep + watermark). Parity references are `main`'s React frontend (`src/`) and the `design/*.pen` files via the pencil MCP.
 - **Parity watermark**: `origin/main` fully ported for repo-and-below as of `1b7ee92` (v0.5.2 line, 2026-08-17); feature-logic lag is M3 scope.
 
 ## 2026-07-18 — Phase 1 kickoff
@@ -181,3 +181,9 @@ M3's slices (0046 §Sequencing) run as serial codex-peer missions, one task at a
 - Deferred the router and frontend halves precisely: this branch's router predates `828c9fc`'s reservation/outbox/listener contract, so the latch is tracked but routing does not consume it until the router/inbox slice; pulling that contract now would drag the whole group. `InboxBlockedPill` and `MissionWorkspace` have no native mission surface yet and remain M4 scope; the pill design is the `InboxBlockedPill` component in `design/runner-mission.pen`.
 - Ported `c5b1ce4` at the native seam: every real quit path atomically calls `mark_running_for_resume_on_launch` before stopping the returned live sessions, including the final event-loop fallback, and stop failures are aggregated after every marked id is attempted. This activates `cb32720`'s feasible quit-side claim handling: an in-flight launch claim is requeued before teardown. Claim consumption/finalization remains deferred because native has no `take_resume_on_launch` queue, `SessionManager::resume_on_launch` path, setting, or launch UI; manual resume must not finish a launch claim. Until a consumer lands, quit stamps accumulate as an undrained `PENDING` backlog, so the launch-queue slice must explicitly drain and discard the pre-existing backlog on first boot or impose a cutoff before enabling auto-resume.
 - Gates: `make verify` green (workspace check, 440 `runner-app` tests, all native/helper tests, clippy `-D warnings`, fmt-check); the 10-test terminal fixture corpus stays green. The sandboxed run hit the expected temporary Unix-socket `EPERM`; the identical permitted run passed.
+
+## 2026-08-18 — Crate renames (decision 7)
+
+- One mechanical commit right after M3.4, per the revised decision 7: `crates/runner-app` → `crates/runner-backend` (package `runner-backend`, lib `runner_backend`), `crates/runner-native` → `crates/runner-app` (package/bin `runner-app`, pulse's `-app` convention). Imports, workspace members, Makefile `run` target, and normative doc references updated; historical log/plan narrative keeps the old names.
+- From here the port mapping is `src-tauri/src/*` ↔ `crates/runner-backend/src/*`; **`runner-app` now names the binary** — every future mission goal states this to defuse the name-reuse hazard.
+- Gates: `make verify` green.
diff --git a/docs/impls/gpui-rewrite/plan.md b/docs/impls/gpui-rewrite/plan.md
index a7e8a52..388d8be 100644
--- a/docs/impls/gpui-rewrite/plan.md
+++ b/docs/impls/gpui-rewrite/plan.md
@@ -16,8 +16,8 @@ One native Rust binary. No webview, no JS, no Tauri. The UI is rendered by GPUI
 
 Keep (~33k LOC Rust, extracted into UI-agnostic crates):
 
-- `crates/runner-app/src/session/` — PTY session manager (`portable-pty`).
-- `crates/runner-app/src/router/`, `event_bus/`, `repo/`, `db.rs` (SQLite), `mcp/`, `model.rs`, `error.rs`.
+- `crates/runner-backend/src/session/` — PTY session manager (`portable-pty`).
+- `crates/runner-backend/src/router/`, `event_bus/`, `repo/`, `db.rs` (SQLite), `mcp/`, `model.rs`, `error.rs`.
 - `crates/runner-core/`, `cli/` — untouched.
 - The SQLite schema and NDJSON event-log format — the native app reads the same data; you can switch between old and new app against the same state.
 
@@ -44,7 +44,7 @@ Revised 2026-07-19 by Jason's decision, superseding the original fold-into-main-
 
 Revised again 2026-07-19 (repo split): the pioneer line briefly moved to its own **runner-gpui** repository. Revised again 2026-08-17 (single repo, current state): the line moved back into the `runner` repo as the long-lived `gpui-nightly` branch, pushed at `774aa35` with the standalone repo's full history; the separate GitHub repo is retired, and locally the branch lives in the `runner-gpui` worktree. Rationale: most of the tree differs between the lines anyway, and the shared part is ported by hand either way — one repo keeps issues, CI, and history together without cross-repo remote juggling.
 
-- **Cross-branch flow**: backend changes on `main` are ported onto `gpui-nightly` by conscious cherry-pick, hand-relocated from `src-tauri/src/*` into `crates/runner-app/*` paths. Nothing flows automatically in either direction. Schema- and protocol-affecting changes (`db.rs` migrations, the `runner-core` event log, `cli` message shapes) port promptly — both apps must keep reading the same `runner.db` and event logs; feature logic ports when a parity slice needs it.
+- **Cross-branch flow**: backend changes on `main` are ported onto `gpui-nightly` by conscious cherry-pick, hand-relocated from `src-tauri/src/*` into `crates/runner-backend/*` paths. Nothing flows automatically in either direction. Schema- and protocol-affecting changes (`db.rs` migrations, the `runner-core` event log, `cli` message shapes) port promptly — both apps must keep reading the same `runner.db` and event logs; feature logic ports when a parity slice needs it.
 - **Milestone work** happens on task branches off `gpui-nightly`, merged back only after human verification.
 - **Cutover (Phase 6)** is a branch promotion: `gpui-nightly`'s tree replaces `main` in this repo.
 
@@ -55,12 +55,12 @@ Build: the pioneer line has Rust-only `fmt`, `clippy`, `test`, and `run` Make ta
 2026-08-17 (Jason):
 
 1. **`main` owns the design.** The whole product design follows `main`, including the node-tree sidebar (Feature 44). The GPUI line does not fork product decisions.
-2. **Repo-and-below is identical.** `crates/runner-core`, `cli/`, `db.rs` + migrations, and `repo/` must match `main` line-for-line (modulo file paths: `src-tauri/src/*` ↔ `crates/runner-app/src/*`). Anything GPUI-specific lives in the adapter layer (`ops/`) or above — never in repo/db. Migration numbers are allocated on `main` only; this branch never adds its own.
+2. **Repo-and-below is identical.** `crates/runner-core`, `cli/`, `db.rs` + migrations, and `repo/` must match `main` line-for-line (modulo file paths: `src-tauri/src/*` ↔ `crates/runner-backend/src/*`). Anything GPUI-specific lives in the adapter layer (`ops/`) or above — never in repo/db. Migration numbers are allocated on `main` only; this branch never adds its own.
 3. **Product UI never changes; only the tech stack changes.** The GPUI app renders the same surfaces, flows, and copy as `main`'s current React app. Divergence is a bug, not a design opportunity.
 4. **Terminal architecture mimics Zed's `terminal` / `terminal_view` crate split** (studied from the local checkout at `~/repos/gui/zed`, tree of 2026-08-17), but on **upstream `alacritty_terminal`** from crates.io — not Zed's fork.
 5. **Framework: `gpui-ce`** (see §Framework).
 6. **Updater (Phase 5): Sparkle via the pulse pattern** (see §Roadmap, Phase 5).
-7. **Crate renames after the M3 session-hardening slice** (timing revised 2026-08-18; originally at Phase 6 cutover): `runner-app` → `runner-backend` (the UI-agnostic core the two frontends shared), `runner-native` → `runner-app` (the binary; pulse convention: `-app` = the application). Lands as one mechanical commit at the slice boundary right after M3.4 (Cargo package names, imports, Makefile/CI, doc references), gated on `make verify` — so M4's UI code, the bulk of new code in this program, is written under the final crate layout. From then on the port mapping is `src-tauri/src/*` ↔ `crates/runner-backend/src/*`, and every mission goal states it explicitly with a warning that `runner-app` now names the binary — the name reuse is the wrong-crate hazard that kept this at cutover originally.
+7. **Crate renames after the M3 session-hardening slice** (timing revised 2026-08-18; originally at Phase 6 cutover): `runner-app` → `runner-backend` (the UI-agnostic core the two frontends shared), `runner-native` → `runner-app` (the binary; pulse convention: `-app` = the application). Landed 2026-08-18 as one mechanical commit right after M3.4 (Cargo package names, imports, Makefile, doc references), gated on `make verify` — so M4's UI code, the bulk of new code in this program, is written under the final crate layout. From then on the port mapping is `src-tauri/src/*` ↔ `crates/runner-backend/src/*`, and every mission goal states it explicitly with a warning that `runner-app` now names the binary — the name reuse is the wrong-crate hazard that kept this at cutover originally.
 
 2026-08-18 (Jason):
 
@@ -83,7 +83,7 @@ Build: the pioneer line has Rust-only `fmt`, `clippy`, `test`, and `run` Make ta
 
 ### A2. DB layer: migrations 0014–0020 + backfills, verbatim
 
-Copy `main`'s `src-tauri/src/db.rs` and `src-tauri/migrations/` over `crates/runner-app/`'s, adjusting only the module path prefix. New content: `0014_nodes.sql` (nodes table + 1:1 row copy from folders/tabs), `0015_retire_folders.sql` (drops legacy tables), `0016_session_last_size`, `0017_session_resume_on_launch`, `0018_slot_model_override`, `0019_session_agent_options`, `0020_slot_effort_override`, plus the Rust backfill steps (`backfill_0014_nodes`, `backfill_0015_retire_folders`) and the peer-coding-crew seed (`d04ce3f`).
+Copy `main`'s `src-tauri/src/db.rs` and `src-tauri/migrations/` over `crates/runner-backend/`'s, adjusting only the module path prefix. New content: `0014_nodes.sql` (nodes table + 1:1 row copy from folders/tabs), `0015_retire_folders.sql` (drops legacy tables), `0016_session_last_size`, `0017_session_resume_on_launch`, `0018_slot_model_override`, `0019_session_agent_options`, `0020_slot_effort_override`, plus the Rust backfill steps (`backfill_0014_nodes`, `backfill_0015_retire_folders`) and the peer-coding-crew seed (`d04ce3f`).
 
 ### A3. Repo layer: adopt `main`'s files, retire ours
 
@@ -117,9 +117,9 @@ Mirror Zed's two-crate shape (reference: `~/repos/gui/zed/crates/terminal` and `
 | `terminal/src/alacritty.rs` + `alacritty/hyperlinks.rs` | isolation of `alacritty_terminal` API surface: grid iteration, selection types, event glue | `runner-terminal/src/alacritty.rs` (deferred until the view side needs it) |
 | `terminal/src/mappings/{keys,mouse,colors}.rs` | keystroke→escape encoding, mouse reports, color conversion | `runner-terminal/src/mappings.rs` |
 | `terminal/src/pty_info.rs` | foreground-process info | **not ported** — process identity is `SessionManager`'s domain |
-| `terminal_view/src/terminal_element.rs` | GPUI `Element`: layout → batched text runs/rects/cursor, paint, IME `InputHandler` | stays in `runner-native/src/terminal_element.rs` (keeps the per-cell-origin alignment strategy) |
-| `terminal_view/src/terminal_view.rs` | focus, key dispatch, blink, context menu | `runner-native` chat/pane views |
-| `terminal_view/src/{terminal_panel,persistence,scrollbar,path_like_target}.rs` | workspace integration | `runner-native` pane layout / future slices |
+| `terminal_view/src/terminal_element.rs` | GPUI `Element`: layout → batched text runs/rects/cursor, paint, IME `InputHandler` | stays in `runner-app/src/terminal_element.rs` (keeps the per-cell-origin alignment strategy) |
+| `terminal_view/src/terminal_view.rs` | focus, key dispatch, blink, context menu | `runner-app` chat/pane views |
+| `terminal_view/src/{terminal_panel,persistence,scrollbar,path_like_target}.rs` | workspace integration | `runner-app` pane layout / future slices |
 
 **Deliberate deviations from Zed:**
 
@@ -147,8 +147,8 @@ Each milestone is a task branch off `gpui-nightly`, human-verified before merge.
 2. **M1 — repo-and-below parity** ✓ (2026-08-17; A1–A3 + minimal B): protocol crates wholesale; db + migrations + repo verbatim; `ops/` adapter updated; sidebar rewired onto nodes far enough to compile and function. Gate: migration test on a *copy* of a production `runner.db`, then the A/B switch test — Tauri `main` build and GPUI build alternately opening the same copy.
 3. **M2 — terminal split** ✓ (2026-08-17; C): extract `runner-terminal`, consolidate input encoding into `mappings`, move the fixture corpus. No rendering change; corpus green.
 4. **M3 — feature-parity slices** (in progress; A4 + B function, dogfood order): session hardening → runtimes/model-effort pickers → node sidebar polish + pinned section → mission feed (read-mostly + channel composer) → pagination/update checks/misc. Run as serial codex-peer missions; task numbering (M3.1, M3.2, …) pinned in the [program log](impl_log.md)'s 2026-08-18 breakdown entry. Each slice daily-driven before the next.
-5. **M4 — UI parity** (new 2026-08-18): bring the native app to full product-UI parity with `main` — this restores the surface breadth of the original Phase 4 list that M3's backend-first slices deliberately defer. Entry task is a **surface inventory**: walk `main`'s `src/` (7 pages, ~30 components + `settings/` + `ui/`) and the `design/*.pen` files, classify every surface as present / unstyled / missing in `runner-native`, and pin the resulting task list in the program log (continuing the serial-mission numbering). Known scope: chat surface + composer styling; tab bar and layout picker; sidebar visual polish beyond M3's functional parity; mission workspace UI; runners/crews CRUD pages; settings; modals and dialogs; command palette; themes as data (Tokyo Night + light); window chrome per §UI reference (hidden titlebar, traffic lights, drag areas — pulse pattern); multi-window; and **terminal-pane IME** (marked-text composition and candidate-window positioning in the focused terminal, committed UTF-8 forwarded through `SessionManager`, raw handling preserved for control/navigation/function keys — a cutover blocker carried from Phase 3). Exit gate: side-by-side parity review against the Tauri app on every surface — same surface, same flow, same copy — and the native app is the daily driver for all workflows, not just chats.
-6. **M5 — sweep + watermark** (was 0046's M4): diff `crates/runner-app` against `main`'s `src-tauri/src` module-by-module; the diff should be adapter-shaped only. Record the synced `main` SHA in this doc as the watermark; subsequent `main` backend commits port promptly (schema/protocol) or per-slice (features).
+5. **M4 — UI parity** (new 2026-08-18): bring the native app to full product-UI parity with `main` — this restores the surface breadth of the original Phase 4 list that M3's backend-first slices deliberately defer. Entry task is a **surface inventory**: walk `main`'s `src/` (7 pages, ~30 components + `settings/` + `ui/`) and the `design/*.pen` files, classify every surface as present / unstyled / missing in `runner-app` (the binary crate), and pin the resulting task list in the program log (continuing the serial-mission numbering). Known scope: chat surface + composer styling; tab bar and layout picker; sidebar visual polish beyond M3's functional parity; mission workspace UI; runners/crews CRUD pages; settings; modals and dialogs; command palette; themes as data (Tokyo Night + light); window chrome per §UI reference (hidden titlebar, traffic lights, drag areas — pulse pattern); multi-window; and **terminal-pane IME** (marked-text composition and candidate-window positioning in the focused terminal, committed UTF-8 forwarded through `SessionManager`, raw handling preserved for control/navigation/function keys — a cutover blocker carried from Phase 3). Exit gate: side-by-side parity review against the Tauri app on every surface — same surface, same flow, same copy — and the native app is the daily driver for all workflows, not just chats.
+6. **M5 — sweep + watermark** (was 0046's M4): diff `crates/runner-backend` against `main`'s `src-tauri/src` module-by-module; the diff should be adapter-shaped only. Record the synced `main` SHA in this doc as the watermark; subsequent `main` backend commits port promptly (schema/protocol) or per-slice (features).
 
 ### Phase 5 — App-shell services (replace what Tauri gave for free)