diff --git a/crates/ide-agent/src/lib.rs b/crates/ide-agent/src/lib.rs
index 437dac00..72f61e73 100644
--- a/crates/ide-agent/src/lib.rs
+++ b/crates/ide-agent/src/lib.rs
@@ -21,7 +21,7 @@ use ide_jsonrpc::{Framing, Handler, Peer, RpcError, codes};
 use parking_lot::{Mutex, RwLock};
 use serde::{Deserialize, Serialize};
 use serde_json::{Value, json};
-use std::collections::{BTreeSet, HashMap, VecDeque};
+use std::collections::{BTreeMap, BTreeSet, HashMap, VecDeque};
 use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicBool, AtomicU32, Ordering};
 use std::sync::{Arc, Weak};
@@ -152,6 +152,9 @@ struct TaskFile {
     /// Settings the user chose, re-applied to every new or reloaded session.
     #[serde(default)]
     wanted: Vec<AgentConfigChoice>,
+    /// In the project's own checkout: files already changed when the task started.
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    before: BTreeMap<String, worktree::Stamp>,
 }
 
 struct TaskState {
@@ -159,6 +162,7 @@ struct TaskState {
     session_id: Option<String>,
     timeline: Timeline,
     wanted: Vec<AgentConfigChoice>,
+    before: Arc<BTreeMap<String, worktree::Stamp>>,
     /// A turn is running or about to (prompts arriving now are queued).
     busy: bool,
 }
@@ -310,18 +314,20 @@ impl AgentManager {
         let prompt = clean(req.prompt).ok_or_else(|| IdeError::invalid("describe the task first"))?;
         let title = title_of(&prompt);
         let root = self.shared.paths.project_root.clone();
-        let (cwd, branch, base, base_commit) = match req.isolation {
+        let (cwd, branch, base, base_commit, before) = match req.isolation {
             Isolation::Worktree => {
                 let dir = self.shared.paths.worktrees_dir.clone();
                 let (t, b) = (title.clone(), req.base.clone());
                 let c = blocking(move || worktree::create(&root, &dir, &t, b.as_deref())).await?;
-                (c.path, Some(c.branch), Some(c.base), Some(c.base_commit))
+                (c.path, Some(c.branch), Some(c.base), Some(c.base_commit), BTreeMap::new())
             }
             Isolation::Local => {
                 let r = root.clone();
-                let head = blocking(move || worktree::head_of(&r)).await.ok();
+                let (head, before) =
+                    blocking(move || Ok((worktree::head_of(&r).ok(), worktree::snapshot(&r).unwrap_or_default())))
+                        .await?;
                 let (base, commit) = head.unzip();
-                (root, None, base, commit)
+                (root, None, base, commit, before)
             }
         };
         // Until the session reports its own, show what the agent offered last time with the choices applied.
@@ -351,7 +357,7 @@ impl AgentManager {
             usage: None,
             queue: Vec::new(),
         };
-        let file = TaskFile { task: task.clone(), session_id: None, entries: Vec::new(), wanted: req.config };
+        let file = TaskFile { task: task.clone(), session_id: None, entries: Vec::new(), wanted: req.config, before };
         let handle = Task::restore(file, self.shared.clone());
         handle.state.lock().busy = true;
         self.tasks.write().insert(task.id.clone(), handle.clone());
@@ -529,8 +535,10 @@ impl AgentManager {
 
     /// Files the task changed since it started.
     pub async fn changes(&self, id: &str) -> IdeResult<Vec<AgentChange>> {
-        let (cwd, base) = self.task(id)?.cwd_and_base();
-        blocking(move || worktree::changes(&cwd, &base)).await
+        let task = self.task(id)?;
+        let (cwd, base) = task.cwd_and_base();
+        let before = task.state.lock().before.clone();
+        blocking(move || Ok(worktree::without_untouched(worktree::changes(&cwd, &base)?, &before))).await
     }
 
     /// Content of `path` (in the task's directory) when the task started.
@@ -560,6 +568,7 @@ impl Task {
                 session_id: file.session_id,
                 timeline,
                 wanted: file.wanted,
+                before: Arc::new(file.before),
                 busy: false,
             }),
             live: Mutex::new(None),
@@ -616,6 +625,7 @@ impl Task {
                 session_id: s.session_id.clone(),
                 entries: s.timeline.entries.clone(),
                 wanted: s.wanted.clone(),
+                before: (*s.before).clone(),
             })
         };
         let path = self.shared.paths.store_dir.join(format!("{}.json", self.id));
diff --git a/crates/ide-agent/src/worktree.rs b/crates/ide-agent/src/worktree.rs
index 5563cf04..7f385afc 100644
--- a/crates/ide-agent/src/worktree.rs
+++ b/crates/ide-agent/src/worktree.rs
@@ -3,7 +3,9 @@
 use crate::model::AgentChange;
 use ide_core::{IdeError, IdeResult, IpcPath};
 use ide_vcs::{ChangeKind, Repo};
+use std::collections::BTreeMap;
 use std::path::{Path, PathBuf};
+use std::time::UNIX_EPOCH;
 
 pub(crate) struct Created {
     pub path: PathBuf,
@@ -74,6 +76,25 @@ pub(crate) fn changes(cwd: &Path, base: &str) -> IdeResult<Vec<AgentChange>> {
     Ok(out)
 }
 
+/// Size and modification time of a file, `None` once it is gone.
+pub(crate) type Stamp = Option<(u64, u128)>;
+
+fn stamp(path: &Path) -> Stamp {
+    let meta = std::fs::metadata(path).ok()?;
+    let modified = meta.modified().ok()?.duration_since(UNIX_EPOCH).ok()?.as_nanos();
+    Some((meta.len(), modified))
+}
+
+/// The files already changed in `cwd` against `HEAD`, stamped so later edits to them show.
+pub(crate) fn snapshot(cwd: &Path) -> IdeResult<BTreeMap<String, Stamp>> {
+    Ok(changes(cwd, "HEAD")?.into_iter().map(|c| (c.rel_path, stamp(&c.path))).collect())
+}
+
+/// Drops the changes that were there before the task and haven't been touched since.
+pub(crate) fn without_untouched(changes: Vec<AgentChange>, before: &BTreeMap<String, Stamp>) -> Vec<AgentChange> {
+    changes.into_iter().filter(|c| before.get(&c.rel_path).is_none_or(|s| *s != stamp(&c.path))).collect()
+}
+
 pub(crate) fn file_at(cwd: &Path, path: &Path, rev: &str) -> IdeResult<Option<String>> {
     repo_at(cwd)?.file_at(path, Some(rev))
 }
@@ -148,6 +169,17 @@ mod tests {
         let base_text = file_at(&created.path, &created.path.join("a.txt"), &created.base_commit).unwrap();
         assert_eq!(base_text.as_deref(), Some("one\ntwo\n"));
 
+        // Changes already in the checkout drop out until they are edited again.
+        let before = snapshot(&created.path).unwrap();
+        std::fs::write(created.path.join("b.txt"), "b\n").unwrap();
+        let rels = |c: Vec<AgentChange>| c.into_iter().map(|c| c.rel_path).collect::<Vec<_>>();
+        let after = changes(&created.path, "HEAD").unwrap();
+        assert_eq!(rels(without_untouched(after, &before)), ["b.txt"]);
+        std::thread::sleep(std::time::Duration::from_millis(10));
+        std::fs::write(created.path.join("new.txt"), "x\ny\nz\n").unwrap();
+        let after = changes(&created.path, "HEAD").unwrap();
+        assert_eq!(rels(without_untouched(after, &before)), ["b.txt", "new.txt"]);
+
         // A second task with the same title gets its own worktree.
         assert_eq!(create(&repo, &tmp.path().join("wt"), "Edit A", None).unwrap().branch, "agent/edit-a-2");
         remove(&repo, &created.path).unwrap();
diff --git a/src/features/agents/Home.module.css b/src/features/agents/Home.module.css
index 24d8d173..f8622115 100644
--- a/src/features/agents/Home.module.css
+++ b/src/features/agents/Home.module.css
@@ -34,6 +34,15 @@
   padding: 0 2px;
   font-size: var(--fs-small);
 }
+/* The current branch, read-only: same height and colour as the pickers beside it. */
+.branch {
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  height: var(--h-control);
+  padding: 0 6px;
+  color: var(--fg-secondary);
+}
 .project {
   margin-right: 6px;
   color: var(--fg-muted);
diff --git a/src/features/agents/HomeEditor.tsx b/src/features/agents/HomeEditor.tsx
index 598e4210..ab65f9ce 100644
--- a/src/features/agents/HomeEditor.tsx
+++ b/src/features/agents/HomeEditor.tsx
@@ -4,7 +4,7 @@ import type { Branch } from "@/bindings";
 import { call, commands } from "@/platform/ipc";
 import { useTx, useTxTemplate } from "@/platform/i18n";
 import { useProject } from "@/platform/project";
-import { Button, Select, T, type SelectOption } from "@/ui";
+import { Button, Icon, Select, T, type SelectOption } from "@/ui";
 import { Composer } from "./Composer";
 import { canSend, emptyDraft } from "./composerModel";
 import { ConfigPickers } from "./ConfigPickers";
@@ -107,6 +107,17 @@ export function HomeEditor() {
             ]}
             onChange={(isolation) => updateDraft({ isolation })}
           />
+          {draft.isolation === "local" && current && (
+            <>
+              <span className={styles.note}>
+                <T>on</T>
+              </span>
+              <span className={styles.branch}>
+                <Icon name="branch" size={14} />
+                {current}
+              </span>
+            </>
+          )}
           {draft.isolation === "worktree" && branches.length > 0 && (
             <>
               <span className={styles.note}>
diff --git a/src/platform/locales/text/zh.json b/src/platform/locales/text/zh.json
index e4adbc1a..5a97da4a 100644
--- a/src/platform/locales/text/zh.json
+++ b/src/platform/locales/text/zh.json
@@ -3216,6 +3216,7 @@
   "away from your changes": "不影响你的改动",
   "edits your files directly": "直接修改你的文件",
   "from": "基于",
+  "on": "位于",
   "Models and modes appear after this agent's first task.": "这个 agent 跑完第一个任务后会显示模型和模式。",
   "Queue a message for when the agent is done (⌘↵ sends it now)": "排队一条消息，agent 做完后发送（⌘↵ 立即发送）",
   "Couldn't send the message": "消息发送失败",