diff --git a/apps/server/src/terminal/Manager.test.ts b/apps/server/src/terminal/Manager.test.ts
index 42ebe1a0e16d..d4056e74fa9e 100644
--- a/apps/server/src/terminal/Manager.test.ts
+++ b/apps/server/src/terminal/Manager.test.ts
@@ -747,6 +747,7 @@ it.layer(
           threadId: "thread-1",
           terminalId: DEFAULT_TERMINAL_ID,
           afterSequence: initialSequence,
+          afterEpoch: initialSnapshot.snapshot.attachEpoch,
         },
         (event) => Ref.update(resumedEvents, (events) => [...events, event]),
       );
@@ -775,6 +776,7 @@ it.layer(
           threadId: "thread-1",
           terminalId: DEFAULT_TERMINAL_ID,
           afterSequence: opened.sequence,
+          afterEpoch: opened.attachEpoch,
         },
         (event) => Ref.update(attachEvents, (events) => [...events, event]),
       );
@@ -799,6 +801,7 @@ it.layer(
           threadId: "thread-1",
           terminalId: DEFAULT_TERMINAL_ID,
           afterSequence: opened.sequence + 1,
+          afterEpoch: opened.attachEpoch,
         },
         (event) => Ref.update(attachEvents, (events) => [...events, event]),
       );
@@ -835,6 +838,7 @@ it.layer(
           threadId: "thread-1",
           terminalId: DEFAULT_TERMINAL_ID,
           afterSequence: opened.sequence,
+          afterEpoch: opened.attachEpoch,
         },
         (event) => Ref.update(attachEvents, (events) => [...events, event]),
       );
diff --git a/apps/server/src/terminal/Manager.ts b/apps/server/src/terminal/Manager.ts
index 8599f5bea3b3..66f5d405fb62 100644
--- a/apps/server/src/terminal/Manager.ts
+++ b/apps/server/src/terminal/Manager.ts
@@ -254,6 +254,8 @@ interface TerminalSessionState {
   exitSignal: number | null;
   updatedAt: string;
   eventSequence: number;
+  /** Coder: a new value per shell session, because each session restarts its sequences. */
+  attachEpoch: string;
   inputCount: number;
   cols: number;
   rows: number;
@@ -346,6 +348,7 @@ function snapshot(session: TerminalSessionState): TerminalSessionSnapshot {
     label: terminalWireLabel(session),
     updatedAt: session.updatedAt,
     sequence: session.eventSequence,
+    attachEpoch: session.attachEpoch,
   };
 }
 
@@ -2660,6 +2663,7 @@ export const makeWithOptions = Effect.fn("TerminalManager.makeWithOptions")(func
         exitSignal: null,
         updatedAt: yield* nowIso,
         eventSequence: 0,
+        attachEpoch: crypto.randomUUID(),
         inputCount: 0,
         cols,
         rows,
@@ -2863,6 +2867,10 @@ export const makeWithOptions = Effect.fn("TerminalManager.makeWithOptions")(func
     const afterSequence = input.afterSequence;
     const snapshotSequence = initialSnapshot.sequence;
     if (afterSequence === undefined || snapshotSequence === undefined) return null;
+    // A cursor from another shell session numbers different events.
+    if (input.afterEpoch === undefined || input.afterEpoch !== initialSnapshot.attachEpoch) {
+      return null;
+    }
     if (afterSequence > snapshotSequence) return null;
     if (afterSequence === snapshotSequence) return [];
     const replay = attachReplay.get(toSessionKey(input.threadId, input.terminalId));
@@ -3147,6 +3155,7 @@ export const makeWithOptions = Effect.fn("TerminalManager.makeWithOptions")(func
         exitSignal: null,
         updatedAt: yield* nowIso,
         eventSequence: 0,
+        attachEpoch: crypto.randomUUID(),
         inputCount: 0,
         cols,
         rows,
diff --git a/apps/web/src/components/GitActionsControl.tsx b/apps/web/src/components/GitActionsControl.tsx
index 79ed4a4c1b3a..4dee0914b47a 100644
--- a/apps/web/src/components/GitActionsControl.tsx
+++ b/apps/web/src/components/GitActionsControl.tsx
@@ -1088,6 +1088,17 @@ export default function GitActionsControl({
   const changesTotals = gitStatusForActions?.branchChanges ?? gitStatusForActions?.workingTree;
 
   const allFiles = gitStatusForActions?.workingTree.files ?? [];
+  // Coder: status paths are repository-relative, and the Files surface opens paths relative to
+  // the thread's folder, which can be a subfolder of the repository.
+  const changedFileOpenPath = (filePath: string): string | null => {
+    const rootPath = gitStatusForActions?.workingTree.rootPath;
+    if (!rootPath || !gitCwd) return filePath;
+    const root = rootPath.replace(/\/+$/, "");
+    const base = gitCwd.replace(/\/+$/, "");
+    if (!base.startsWith(`${root}/`)) return filePath;
+    const prefix = `${base.slice(root.length + 1)}/`;
+    return filePath.startsWith(prefix) ? filePath.slice(prefix.length) : null;
+  };
   const selectedFiles = allFiles.filter((f) => !excludedFiles.has(f.path));
   const allSelected = excludedFiles.size === 0;
   const noneSelected = selectedFiles.length === 0;
@@ -1903,8 +1914,11 @@ export default function GitActionsControl({
                                 <button
                                   type="button"
                                   className="flex min-w-0 flex-1 items-center justify-between gap-3 text-left"
-                                  onClick={() => onOpenFile?.(file.path)}
-                                  disabled={!onOpenFile}
+                                  onClick={() => {
+                                    const openPath = changedFileOpenPath(file.path);
+                                    if (openPath !== null) onOpenFile?.(openPath);
+                                  }}
+                                  disabled={!onOpenFile || changedFileOpenPath(file.path) === null}
                                 >
                                   <StartTruncatedPath
                                     path={file.path}
diff --git a/docs/internals/coder-only.md b/docs/internals/coder-only.md
index f8d0cd858377..25323d523498 100644
--- a/docs/internals/coder-only.md
+++ b/docs/internals/coder-only.md
@@ -764,7 +764,8 @@ listed here is drift to remove rather than fork behavior to keep.
   - `ModelCapabilities` carries the provider-reported `supportedRuntimeModes`; custom models use
     `CustomModelCapabilities`, which cannot declare them.
   - Tool items keep legacy screenshot `artifacts`; rate-limit events carry the raw payload.
-  - Terminal attach input adds `afterSequence`, and the attach stream adds a `resumed` event.
+  - Terminal attach input adds `afterSequence` and `afterEpoch`, terminal snapshots add
+    `attachEpoch`, and the attach stream adds a `resumed` event.
   - Claude launch args reach the workspace CLI except the stream-json transport flags. `ClaudeAgentSdk.ts` passes
     `mcpServers` and `strictMcpConfig` as the SDK does and rejects in-process (`sdk`) MCP servers,
     which the CLI transport cannot host.
@@ -777,12 +778,14 @@ listed here is drift to remove rather than fork behavior to keep.
 - **Terminals.** `terminal/Manager.ts` is upstream's. Coder deltas: it records each terminal's
   attach events in a bounded replay window (`DEFAULT_ATTACH_REPLAY_*` in `Manager.ts`) and answers an
   attach with `afterSequence` by replaying the missed events and a `resumed` event instead of a
-  snapshot when the window still covers the gap. Terminals poll the process table themselves
+  snapshot when the window still covers the gap. Each shell session restarts its sequences, so
+  it also has an `attachEpoch`, and a cursor whose `afterEpoch` names another session gets a
+  snapshot. Terminals poll the process table themselves
   (no resource telemetry), register no ports for preview discovery, record no metrics, and get
   no managed ACP install directories on `PATH`. In the browser, the terminal session state, output model,
   drawer, and UI state store are upstream's; client-runtime adds `TerminalBufferCache`, a bounded
-  in-memory cache that seeds a reattach and supplies its `afterSequence`, and tracks the last
-  applied sequence. Each attach attempt reads `afterSequence` from that cache, beside upstream's
+  in-memory cache that seeds a reattach and supplies its `afterSequence` and `afterEpoch`, and
+  tracks the last applied sequence and session epoch. Each attach attempt reads `afterSequence` from that cache, beside upstream's
   `resume` flag, and a resumed attach of a closed terminal gets upstream's `closed` event. `ThreadTerminalDrawer` never opens terminal links (there is no editor or
   preview surface).
 - **Command palette.** `CommandPalette.tsx` is upstream's, including its add-project browse,
@@ -927,7 +930,9 @@ listed here is drift to remove rather than fork behavior to keep.
   [Network and transfer constraints](#network-and-transfer-constraints)), and a PDF keeps the
   built-in viewer's frame where upstream uses `<embed>`, which the gateway's `object-src 'none'`
   blocks; there is no
-  open-in-editor or reveal action, and the tree adds Copy path.
+  open-in-editor or reveal action, and the tree adds Copy path. Changed files in the Git actions
+  dialog open in the Files surface, with repository-relative status paths mapped to the thread's
+  folder; a file outside a subfolder project cannot be opened there.
   `env.ts` reports `isElectron = false` for upstream's desktop branches.
 - **Merge requests.** Upstream's page, panel, stack menu, and right-panel tabs, GitLab-only. Diffs
   come over the `pullRequests.diff` RPC without upstream's cross-environment GitHub routing,
diff --git a/packages/client-runtime/src/state/terminal.ts b/packages/client-runtime/src/state/terminal.ts
index 2fcba3af2ea8..c9d6d1abe25d 100644
--- a/packages/client-runtime/src/state/terminal.ts
+++ b/packages/client-runtime/src/state/terminal.ts
@@ -69,9 +69,12 @@ export function createTerminalEnvironmentAtoms<R, E>(
               // Coder: each attempt resumes after the last sequence the cache applied.
               const current = terminalBufferCache.read(environmentId, input);
               const afterSequence = current.version === 0 ? null : (current.sequence ?? null);
+              const afterEpoch = current.epoch ?? null;
               return {
                 ...(replied ? { ...input, resume: true } : input),
-                ...(afterSequence === null ? {} : { afterSequence }),
+                ...(afterSequence === null || afterEpoch === null
+                  ? {}
+                  : { afterSequence, afterEpoch }),
               };
             }),
           ).pipe(
diff --git a/packages/client-runtime/src/state/terminalSession.ts b/packages/client-runtime/src/state/terminalSession.ts
index b76b98bada0f..fcbd42cc5c6a 100644
--- a/packages/client-runtime/src/state/terminalSession.ts
+++ b/packages/client-runtime/src/state/terminalSession.ts
@@ -44,6 +44,8 @@ export interface TerminalBufferState {
   readonly lifecycleVersion: number;
   /** Coder: the last applied attach-event sequence, sent as `afterSequence` on reattach. */
   readonly sequence?: number | null;
+  /** Coder: the shell session that sequence belongs to, sent as `afterEpoch`. */
+  readonly epoch?: string | null;
 }
 
 export interface KnownTerminalSessionTarget {
@@ -152,9 +154,15 @@ export function applyTerminalAttachStreamEvent(
       : "sequence" in event && typeof event.sequence === "number"
         ? event.sequence
         : (current.sequence ?? null);
-  return next === current && sequence === (current.sequence ?? null)
+  const epoch =
+    event.type === "snapshot" || event.type === "restarted"
+      ? (event.snapshot.attachEpoch ?? null)
+      : (current.epoch ?? null);
+  return next === current &&
+    sequence === (current.sequence ?? null) &&
+    epoch === (current.epoch ?? null)
     ? current
-    : { ...next, sequence };
+    : { ...next, sequence, epoch };
 }
 
 function applyUpstreamTerminalAttachStreamEvent(
diff --git a/packages/contracts/src/terminal.ts b/packages/contracts/src/terminal.ts
index d67a67a35eff..bc675b70b908 100644
--- a/packages/contracts/src/terminal.ts
+++ b/packages/contracts/src/terminal.ts
@@ -53,8 +53,10 @@ export const TerminalAttachInput = Schema.Struct({
   env: Schema.optional(TerminalEnvSchema),
   providerInstanceId: Schema.optional(ProviderInstanceId),
   restartIfNotRunning: Schema.optional(Schema.Boolean),
-  // Coder: the last event sequence the client applied, for replay-window resume.
+  // Coder: the last event sequence the client applied, for replay-window resume, and the session
+  // epoch it was applied in; sequences restart with every new shell session.
   afterSequence: Schema.optional(Schema.Int.check(Schema.isGreaterThanOrEqualTo(0))),
+  afterEpoch: Schema.optional(Schema.String),
   // Resubscriptions preserve stopped terminals; unknown IDs recover after a server restart.
   resume: Schema.optional(Schema.Boolean),
 });
@@ -113,6 +115,8 @@ export const TerminalSessionSnapshot = Schema.Struct({
   label: Schema.String.check(Schema.isMaxLength(128)),
   updatedAt: Schema.String,
   sequence: Schema.optional(Schema.Int.check(Schema.isGreaterThanOrEqualTo(0))),
+  // Coder: identifies the shell session whose sequences a replay-window resume refers to.
+  attachEpoch: Schema.optional(Schema.String),
 });
 export type TerminalSessionSnapshot = typeof TerminalSessionSnapshot.Type;