diff --git a/codex-rs/app-server-client/src/cloud.rs b/codex-rs/app-server-client/src/cloud.rs
index 03553d14db..1a356ece4c 100644
--- a/codex-rs/app-server-client/src/cloud.rs
+++ b/codex-rs/app-server-client/src/cloud.rs
@@ -19,6 +19,12 @@ use tokio::sync::oneshot;
 /// Unsupported operations must return an explicit error; they must not claim success.
 pub enum CloudOperation {
     Request(Box<ClientRequest>),
+    /// Host project metadata stays on the private transport, outside the app-server wire.
+    StartProjectThread {
+        request_id: RequestId,
+        params: Box<codex_app_server_protocol::ThreadStartParams>,
+        project: codex_cloud_client::ProjectEnvironment,
+    },
     SubmitUserMessage(Box<TurnStartParams>),
     Notify(ClientNotification),
     Resolve {
@@ -124,6 +130,20 @@ impl CloudClient {
 }
 
 impl CloudRequestHandle {
+    pub(crate) async fn start_project_thread(
+        &self,
+        request_id: RequestId,
+        params: codex_app_server_protocol::ThreadStartParams,
+        project: codex_cloud_client::ProjectEnvironment,
+    ) -> io::Result<RequestResult> {
+        self.send(CloudOperation::StartProjectThread {
+            request_id,
+            params: Box::new(params),
+            project,
+        })
+        .await
+    }
+
     /// Submit once with a stable message ID and saved thread settings. The server
     /// starts or steers; an error can mean admission is unknown. Never auto-resend.
     pub async fn submit_user_message(
diff --git a/codex-rs/app-server-client/src/cloud_backend/mod.rs b/codex-rs/app-server-client/src/cloud_backend/mod.rs
index 225a1f9c6c..94d584482f 100644
--- a/codex-rs/app-server-client/src/cloud_backend/mod.rs
+++ b/codex-rs/app-server-client/src/cloud_backend/mod.rs
@@ -180,7 +180,21 @@ async fn run_worker(
                 let _ = command.response.send(Ok(Ok(Value::Null)));
                 return;
             }
-            CloudOperation::Request(request) => Ok((*request, cloud::SubmissionMode::StartIfIdle)),
+            CloudOperation::Request(request) => {
+                Ok((*request, cloud::SubmissionMode::StartIfIdle, None))
+            }
+            CloudOperation::StartProjectThread {
+                request_id,
+                params,
+                project,
+            } => Ok((
+                protocol::ClientRequest::ThreadStart {
+                    request_id,
+                    params: *params,
+                },
+                cloud::SubmissionMode::StartIfIdle,
+                Some(project),
+            )),
             CloudOperation::SubmitUserMessage(params) => Ok((
                 protocol::ClientRequest::TurnStart {
                     // Native admission is keyed by the caller's stable message ID.
@@ -188,6 +202,7 @@ async fn run_worker(
                     params: *params,
                 },
                 cloud::SubmissionMode::Steer,
+                None,
             )),
             CloudOperation::Notify(_) => {
                 Err(eyre!("Cloud client notifications are not supported yet."))
@@ -197,9 +212,9 @@ async fn run_worker(
             )),
         };
         let result = match request {
-            Ok((request, mode)) => tokio::select! {
+            Ok((request, mode, project)) => tokio::select! {
                 _ = output.closed() => return,
-                result = handle_request(request, mode, requests, replies, output) => result,
+                result = handle_request(request, mode, project, requests, replies, output) => result,
             },
             Err(error) => Err(error),
         };
@@ -231,6 +246,7 @@ async fn run_worker(
 async fn handle_request(
     request: protocol::ClientRequest,
     mode: cloud::SubmissionMode,
+    project: Option<cloud::ProjectEnvironment>,
     requests: &mut requests::Requests,
     replies: &mut Replies,
     output: &mpsc::UnboundedSender<AppServerEvent>,
@@ -256,7 +272,7 @@ async fn handle_request(
         replies.admit_turn(&params.thread_id, output)?;
     }
     match replies
-        .while_listening(requests.handle(request, mode, output), output)
+        .while_listening(requests.handle(request, mode, project, output), output)
         .await?
     {
         requests::Response::Value(value) => Ok(value),
diff --git a/codex-rs/app-server-client/src/cloud_backend/requests.rs b/codex-rs/app-server-client/src/cloud_backend/requests.rs
index 6d5814be45..d15943d23b 100644
--- a/codex-rs/app-server-client/src/cloud_backend/requests.rs
+++ b/codex-rs/app-server-client/src/cloud_backend/requests.rs
@@ -54,6 +54,7 @@ impl Requests {
         &mut self,
         request: protocol::ClientRequest,
         mode: cloud::SubmissionMode,
+        project: Option<cloud::ProjectEnvironment>,
         output: &mpsc::UnboundedSender<crate::AppServerEvent>,
     ) -> Result<Response> {
         use protocol::ClientRequest as Request;
@@ -79,7 +80,7 @@ impl Requests {
                         "Cloud conversations start with server defaults. Custom settings are not supported yet."
                     );
                 }
-                let settings = self.client.prewarm_default_thread(model, provider).await?;
+                let settings = self.client.prewarm_thread(model, provider, project).await?;
                 return attach_response(settings);
             }
             Request::ThreadResume { params, .. } => {
diff --git a/codex-rs/app-server-client/src/lib.rs b/codex-rs/app-server-client/src/lib.rs
index d47c1ff152..5b011863f1 100644
--- a/codex-rs/app-server-client/src/lib.rs
+++ b/codex-rs/app-server-client/src/lib.rs
@@ -22,6 +22,7 @@
 
 mod cloud;
 pub mod cloud_backend;
+pub use codex_cloud_client::ProjectEnvironment;
 mod path;
 mod remote;
 mod remote_websocket;
@@ -713,6 +714,27 @@ impl InProcessAppServerRequestHandle {
 }
 
 impl AppServerRequestHandle {
+    /// Starts a native cloud thread with host project metadata without adding wire fields.
+    pub async fn start_cloud_project_thread(
+        &self,
+        request_id: RequestId,
+        params: codex_app_server_protocol::ThreadStartParams,
+        project: codex_cloud_client::ProjectEnvironment,
+    ) -> Result<codex_app_server_protocol::ThreadStartResponse, TypedRequestError> {
+        let response = match self {
+            Self::Cloud(handle) => {
+                handle
+                    .start_project_thread(request_id, params, project)
+                    .await
+            }
+            Self::InProcess(_) | Self::Remote(_) => Err(IoError::new(
+                std::io::ErrorKind::Unsupported,
+                "Project checkout requires the native cloud transport.",
+            )),
+        };
+        decode_typed_response("thread/start", response)
+    }
+
     pub(crate) async fn resolve_server_request(
         &self,
         request_id: RequestId,
diff --git a/codex-rs/cloud-client/src/client_tests.rs b/codex-rs/cloud-client/src/client_tests.rs
index 979f861a79..f333509f7e 100644
--- a/codex-rs/cloud-client/src/client_tests.rs
+++ b/codex-rs/cloud-client/src/client_tests.rs
@@ -231,6 +231,55 @@ async fn activation_preserves_native_settings_and_thread_metadata() {
     assert!(server.requests.try_recv().is_err());
 }
 
+#[tokio::test]
+async fn prewarm_encodes_blank_and_project_managed_environments() {
+    let mut fixture = fixture_responses(vec![
+        response(vec![frame(&[])], tonic::Status::ok("")),
+        response(vec![frame(&[])], tonic::Status::ok("")),
+    ])
+    .await;
+
+    assert!(matches!(
+        fixture
+            .client
+            .prewarm_default_thread(/*model*/ None, /*model_provider*/ None)
+            .await,
+        Err(Error::InvalidResponse)
+    ));
+    assert_request(&mut fixture, "Prewarm", b"\x52\x04\x0a\x02\x0a\x00").await;
+
+    assert!(matches!(
+        fixture
+            .client
+            .prewarm_thread(
+                /*model*/ None,
+                /*model_provider*/ None,
+                Some(ProjectEnvironment {
+                    name: "App".to_owned(),
+                    cwd: Some("/workspace/acme/app".to_owned()),
+                    origin_urls: vec![
+                        "git@github.com:acme/app.git".to_owned(),
+                        "https://github.com/acme/lib.git".to_owned(),
+                    ],
+                }),
+            )
+            .await,
+        Err(Error::InvalidResponse)
+    ));
+    let expected = [
+        b"\x52\x73\x0a\x71\x0a\x6f\x0a\x0d" as &[u8],
+        b"asenvcfg_base",
+        b"\x12\x13/workspace/acme/app",
+        b"\x1a\x49\x0a\x42\x0a\x1d\x2a\x1b",
+        b"git@github.com:acme/app.git",
+        b"\x0a\x21\x2a\x1f",
+        b"https://github.com/acme/lib.git",
+        b"\x12\x03App",
+    ]
+    .concat();
+    assert_request(&mut fixture, "Prewarm", &expected).await;
+}
+
 #[tokio::test]
 async fn prewarm_uses_managed_defaults_and_preserves_resolved_settings() {
     // PrewarmThread uses Thread field numbers but omits turns entirely.
diff --git a/codex-rs/cloud-client/src/lib.rs b/codex-rs/cloud-client/src/lib.rs
index c6b35c337e..e96815509d 100644
--- a/codex-rs/cloud-client/src/lib.rs
+++ b/codex-rs/cloud-client/src/lib.rs
@@ -56,6 +56,7 @@ pub use items::CommandSummary;
 pub use items::ItemLifecycle;
 pub use items::ItemStatus;
 pub use items::ItemSummary;
+pub use prewarm::ProjectEnvironment;
 pub use transcript::FileUpdate;
 pub use transcript::ItemDelta;
 pub use transcript::PatchKind;
diff --git a/codex-rs/cloud-client/src/prewarm.rs b/codex-rs/cloud-client/src/prewarm.rs
index 4cdc9f8bfc..4597eb9e38 100644
--- a/codex-rs/cloud-client/src/prewarm.rs
+++ b/codex-rs/cloud-client/src/prewarm.rs
@@ -6,6 +6,22 @@ use bytes::Bytes;
 use bytes::BytesMut;
 use prost::Message;
 
+/// A local project's GitHub origins to provision in the default cloud environment.
+/// Callers must supply credential-free origin URLs; this client does not inspect local Git state.
+#[derive(Clone)]
+pub struct ProjectEnvironment {
+    pub name: String,
+    pub origin_urls: Vec<String>,
+    /// Working directory inside the managed environment, when a project selects one.
+    pub cwd: Option<String>,
+}
+
+impl std::fmt::Debug for ProjectEnvironment {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("ProjectEnvironment([redacted])")
+    }
+}
+
 impl Client {
     /// Prewarm an ordinary coding thread in the default managed environment.
     /// The service makes it discoverable when it admits the first user message.
@@ -17,6 +33,39 @@ impl Client {
         model: Option<String>,
         model_provider: Option<String>,
     ) -> Result<crate::ThreadActivation, Error> {
+        self.prewarm_thread(model, model_provider, /*project*/ None)
+            .await
+    }
+
+    /// Prewarm a coding thread with an optional project checkout.
+    pub async fn prewarm_thread(
+        &self,
+        model: Option<String>,
+        model_provider: Option<String>,
+        project: Option<ProjectEnvironment>,
+    ) -> Result<crate::ThreadActivation, Error> {
+        let managed = match project {
+            Some(ProjectEnvironment {
+                name,
+                origin_urls,
+                cwd,
+            }) => wire::ManagedEnvironment {
+                environment_config_id: Some("asenvcfg_base".to_owned()),
+                cwd,
+                overrides: Some(wire::EnvironmentOverrides {
+                    repositories: Some(wire::RepositoryOverrides {
+                        values: origin_urls
+                            .into_iter()
+                            .map(|origin_url| wire::RepositoryOverride {
+                                origin_url: Some(origin_url),
+                            })
+                            .collect(),
+                    }),
+                    name: Some(name),
+                }),
+            },
+            None => wire::ManagedEnvironment::default(),
+        };
         let response = self
             .raw_unary(
                 wire::PrewarmRequest {
@@ -24,7 +73,7 @@ impl Client {
                     model_provider,
                     environments: Some(wire::EnvironmentList {
                         values: vec![wire::EnvironmentSelection {
-                            managed: Some(wire::ManagedEnvironment {}),
+                            managed: Some(managed),
                         }],
                     }),
                 },
@@ -79,7 +128,31 @@ mod wire {
         pub managed: Option<ManagedEnvironment>,
     }
     #[derive(Clone, Message)]
-    pub(super) struct ManagedEnvironment {}
+    pub(super) struct ManagedEnvironment {
+        #[prost(string, optional, tag = "1")]
+        pub environment_config_id: Option<String>,
+        #[prost(string, optional, tag = "2")]
+        pub cwd: Option<String>,
+        #[prost(message, optional, tag = "3")]
+        pub overrides: Option<EnvironmentOverrides>,
+    }
+    #[derive(Clone, Message)]
+    pub(super) struct EnvironmentOverrides {
+        #[prost(message, optional, tag = "1")]
+        pub repositories: Option<RepositoryOverrides>,
+        #[prost(string, optional, tag = "2")]
+        pub name: Option<String>,
+    }
+    #[derive(Clone, Message)]
+    pub(super) struct RepositoryOverrides {
+        #[prost(message, repeated, tag = "1")]
+        pub values: Vec<RepositoryOverride>,
+    }
+    #[derive(Clone, Message)]
+    pub(super) struct RepositoryOverride {
+        #[prost(string, optional, tag = "5")]
+        pub origin_url: Option<String>,
+    }
     #[derive(Clone, Message)]
     pub(super) struct PrewarmResponse {
         #[prost(message, optional, tag = "1")]
diff --git a/codex-rs/protocol/src/sanitized_git_url.rs b/codex-rs/protocol/src/sanitized_git_url.rs
index daf6345d8b..c10408b86c 100644
--- a/codex-rs/protocol/src/sanitized_git_url.rs
+++ b/codex-rs/protocol/src/sanitized_git_url.rs
@@ -77,9 +77,13 @@ impl TryFrom<&str> for SanitizedGitUrl {
         // `file://` authority as its host and does not expose its userinfo.
         // Rebuilding only this part also preserves escaped repository paths.
         if let Some((scheme, authority_and_path)) = value.split_once("://") {
-            let authority_end = authority_and_path
-                .find('/')
-                .unwrap_or(authority_and_path.len());
+            // Git treats '?' and '#' as authority text on non-HTTP transports.
+            let authority_end = if matches!(scheme, "http" | "https") {
+                authority_and_path.find(['/', '?', '#'])
+            } else {
+                authority_and_path.find('/')
+            }
+            .unwrap_or(authority_and_path.len());
             let (authority, path) = authority_and_path.split_at(authority_end);
             let Some((_, host)) = authority.rsplit_once('@') else {
                 return Ok(Self(original.to_owned()));
diff --git a/codex-rs/protocol/src/sanitized_git_url_tests.rs b/codex-rs/protocol/src/sanitized_git_url_tests.rs
index dc02f22d8a..48ac354135 100644
--- a/codex-rs/protocol/src/sanitized_git_url_tests.rs
+++ b/codex-rs/protocol/src/sanitized_git_url_tests.rs
@@ -15,6 +15,30 @@ fn removes_https_username_and_password() {
     assert_eq!(url.as_str(), "https://github.com/org/repo.git");
 }
 
+#[test]
+fn http_query_and_fragment_are_outside_the_authority() {
+    for (scheme, suffix) in [("http", "?@github.com/a/b"), ("https", "#@github.com/a/b")] {
+        let expected = format!("{scheme}://example.com{suffix}");
+        for authority in ["example.com", "user:password@example.com"] {
+            let remote = format!("{scheme}://{authority}{suffix}");
+            let sanitized = SanitizedGitUrl::try_from(remote.as_str()).expect("parse remote URL");
+            assert_eq!(sanitized.as_str(), expected);
+        }
+    }
+}
+
+#[test]
+fn non_http_credentials_can_contain_query_and_fragment_delimiters() {
+    for scheme in ["ssh", "git", "file"] {
+        let expected = format!("{scheme}://example.com/org/repo");
+        for password in ["synthetic?value", "synthetic#value"] {
+            let remote = format!("{scheme}://user:{password}@example.com/org/repo");
+            let sanitized = SanitizedGitUrl::try_from(remote.as_str()).expect("parse remote URL");
+            assert_eq!(sanitized.as_str(), expected);
+        }
+    }
+}
+
 /// Tokens placed in the username field are credentials too.
 #[test]
 fn removes_https_username_without_password() {
diff --git a/codex-rs/tui/src/app/agents_overview.rs b/codex-rs/tui/src/app/agents_overview.rs
index c31484dc90..f2518c7d3e 100644
--- a/codex-rs/tui/src/app/agents_overview.rs
+++ b/codex-rs/tui/src/app/agents_overview.rs
@@ -856,6 +856,9 @@ impl App {
             self.select_agent_thread(tui, app_server, root_thread_id)
                 .await?;
         }
+        if self.current_displayed_thread_id() == Some(root_thread_id) {
+            self.remember_attached_host_project(app_server);
+        }
         let read_only = self.chat_widget.is_external_writer_view();
         if !read_only {
             self.replay_agents_overview_requests(app_server, root_thread_id)
diff --git a/codex-rs/tui/src/app/agents_overview_new.rs b/codex-rs/tui/src/app/agents_overview_new.rs
index 43535f8395..aa926e2dd8 100644
--- a/codex-rs/tui/src/app/agents_overview_new.rs
+++ b/codex-rs/tui/src/app/agents_overview_new.rs
@@ -167,6 +167,7 @@ impl App {
                 /*session_start_source*/ None,
                 remote_cwd.as_deref(),
                 selected_profile.as_ref(),
+                self.backend_preference_context.local_cwd.as_deref(),
             )),
         )
         .await;
diff --git a/codex-rs/tui/src/app/backend_selection.rs b/codex-rs/tui/src/app/backend_selection.rs
index e1f5a8f5aa..7fe67dcf4b 100644
--- a/codex-rs/tui/src/app/backend_selection.rs
+++ b/codex-rs/tui/src/app/backend_selection.rs
@@ -76,6 +76,18 @@ impl BackendPreferenceContext {
 }
 
 impl App {
+    pub(super) fn remember_attached_host_project(&mut self, app_server: &AppServerSession) {
+        if !app_server.uses_remote_workspace()
+            && !crate::uses_remote_workspace_or_environment(
+                &self.app_server_target,
+                &self.environment_manager,
+            )
+        {
+            self.backend_preference_context.local_cwd =
+                Some(self.chat_widget.config_ref().cwd.to_path_buf());
+        }
+    }
+
     pub(super) async fn new_thread_host_preference(&self) -> Option<&str> {
         let defaults = &self.local_settings.tui.default_hosts;
         if defaults.is_empty() {
@@ -134,6 +146,9 @@ impl App {
             .get(&owner)
             .cloned()
             .ok_or("Connection settings are unavailable.")?;
+        if settings.target == AppServerTarget::Cloud && self.chat_widget.thread_id().is_some() {
+            self.remember_attached_host_project(backends.session_at(outgoing_slot));
+        }
         let preference = if matches!(session, NewBackendSession::CarryDraft)
             && let Some(key) = backends.preference_key(slot)
         {
@@ -191,6 +206,7 @@ impl App {
                 /*session_start_source*/ None,
                 /*remote_cwd_override*/ None,
                 /*selected_profile*/ None,
+                self.backend_preference_context.local_cwd.as_deref(),
             )
             .await
             .map_err(|error| format!("Failed to start the new conversation: {error}"))?;
diff --git a/codex-rs/tui/src/app/session_lifecycle.rs b/codex-rs/tui/src/app/session_lifecycle.rs
index 5cece94d1d..7f71bd69d0 100644
--- a/codex-rs/tui/src/app/session_lifecycle.rs
+++ b/codex-rs/tui/src/app/session_lifecycle.rs
@@ -1163,6 +1163,7 @@ impl App {
                 session_start_source,
                 /*remote_cwd_override*/ None,
                 /*selected_profile*/ None,
+                self.backend_preference_context.local_cwd.as_deref(),
             )
             .await
         {
@@ -1609,6 +1610,7 @@ impl App {
             .await
         {
             Ok(()) => {
+                self.remember_attached_host_project(app_server);
                 if let Some(mut input) = retained_input {
                     // A successful resume is the authority for clearing the old rejection.
                     input.provider_error = None;
diff --git a/codex-rs/tui/src/app/startup.rs b/codex-rs/tui/src/app/startup.rs
index 434fe9027e..6abd6b8800 100644
--- a/codex-rs/tui/src/app/startup.rs
+++ b/codex-rs/tui/src/app/startup.rs
@@ -1170,6 +1170,7 @@ See the Codex keymap documentation for supported actions and examples."
                     return shutdown_on_startup_error(app_server, &mut other_backends, err).await;
                 }
             }
+            app.remember_attached_host_project(&app_server);
             if let Some(error) = provider_error {
                 app.chat_widget
                     .show_provider_error(error, /*rejected_message_id*/ None);
diff --git a/codex-rs/tui/src/app/tests/background_task_defaults_tests.rs b/codex-rs/tui/src/app/tests/background_task_defaults_tests.rs
index 9123904c51..f0496740c5 100644
--- a/codex-rs/tui/src/app/tests/background_task_defaults_tests.rs
+++ b/codex-rs/tui/src/app/tests/background_task_defaults_tests.rs
@@ -358,12 +358,21 @@ async fn command_center_new_reads_server_defaults_for_actual_destination() -> Re
         } else {
             expected_model.to_string()
         };
+        app.backend_preference_context.local_cwd = Some(launch.path().to_path_buf());
         app.new_agents_overview_session(
             &mut tui,
             &mut server,
             explicit_cwd.then(|| destination.path().to_path_buf().abs()),
         )
         .await?;
+        assert_eq!(
+            app.backend_preference_context.local_cwd.as_deref(),
+            Some(if !mode.starts_with("remote") && explicit_cwd {
+                destination.path()
+            } else {
+                launch.path()
+            }),
+        );
         let cwd = match expected_cwd {
             "launch" => launch.path().display().to_string(),
             "destination" => destination.path().display().to_string(),
@@ -733,6 +742,7 @@ async fn command_center_new_preserves_only_selected_server_profiles() -> Result<
             /*session_start_source*/ None,
             /*remote_cwd_override*/ None,
             Some(&selection),
+            /*host_project_cwd*/ None,
         )
         .await?;
     app.enqueue_primary_thread_session(started.session, started.turns)
@@ -814,9 +824,14 @@ async fn command_center_new_preserves_only_selected_server_profiles() -> Result<
         ServerNotification::ThreadSettingsUpdated(settings),
     )
     .await?;
+    app.backend_preference_context.local_cwd = Some(home.path().to_owned());
     for target in [other, thread_id] {
         app.select_agents_overview_thread(&mut tui, &mut server, target)
             .await?;
+        assert_eq!(
+            app.backend_preference_context.local_cwd.as_deref(),
+            Some(home.path()),
+        );
         assert_eq!(
             app.chat_widget.thread_id(),
             Some(target),
@@ -1284,6 +1299,7 @@ async fn command_center_new_checkout_and_worktree_preserve_source_and_default_br
             .await?;
             let view = app.agents_overview_view(Vec::new(), /*selected_thread_id*/ None);
             app.chat_widget.show_bottom_pane_view(Box::new(view));
+            let host_project = app.backend_preference_context.local_cwd.clone();
             app.start_agents_overview_session(
                 &mut tui,
                 &mut failed_server,
@@ -1293,6 +1309,7 @@ async fn command_center_new_checkout_and_worktree_preserve_source_and_default_br
             )
             .await?;
             assert_eq!(app.chat_widget.thread_id(), Some(second));
+            assert_eq!(app.backend_preference_context.local_cwd, host_project);
             assert_eq!(manager.owner(&unused.root).unwrap(), None);
             assert!(unused.root.exists());
             let rendered = crate::chatwidget::tests::helpers::render_bottom_popup(
diff --git a/codex-rs/tui/src/app/tests/session_lifecycle_requests.rs b/codex-rs/tui/src/app/tests/session_lifecycle_requests.rs
index 0bd84cbe27..4241f9814e 100644
--- a/codex-rs/tui/src/app/tests/session_lifecycle_requests.rs
+++ b/codex-rs/tui/src/app/tests/session_lifecycle_requests.rs
@@ -880,6 +880,7 @@ async fn same_thread_retry_keeps_subscription_and_restores_draft() -> Result<()>
     app.harness_overrides.cwd = Some(app.config.cwd.to_path_buf());
     requests.lock().expect("request recorder lock").clear();
     let mut tui = crate::tui::test_support::make_test_tui()?;
+    app.backend_preference_context.local_cwd = None;
     app.resume_target_session(
         &mut tui,
         &mut app_server,
@@ -892,6 +893,10 @@ async fn same_thread_retry_keeps_subscription_and_restores_draft() -> Result<()>
         },
     )
     .await?;
+    assert_eq!(
+        app.backend_preference_context.local_cwd.as_deref(),
+        Some(app.chat_widget.config_ref().cwd.as_path()),
+    );
     assert_eq!(recorded_params(&requests, "thread/resume").len(), 1);
     assert!(recorded_params(&requests, "thread/unsubscribe").is_empty());
     assert!(!app.chat_widget.is_external_writer_view());
diff --git a/codex-rs/tui/src/app/working_directory.rs b/codex-rs/tui/src/app/working_directory.rs
index 6cdeab2f3e..7a3a7966fb 100644
--- a/codex-rs/tui/src/app/working_directory.rs
+++ b/codex-rs/tui/src/app/working_directory.rs
@@ -466,6 +466,7 @@ impl App {
                     /*session_start_source*/ None,
                     /*remote_cwd_override*/ None,
                     selected_profile.as_ref(),
+                    /*host_project_cwd*/ None,
                 )
                 .await
         };
diff --git a/codex-rs/tui/src/app_server_session.rs b/codex-rs/tui/src/app_server_session.rs
index d87374c570..3c3648db0d 100644
--- a/codex-rs/tui/src/app_server_session.rs
+++ b/codex-rs/tui/src/app_server_session.rs
@@ -5,6 +5,7 @@
 
 mod account;
 pub(crate) use account::SessionAccount;
+mod cloud_project;
 mod daybreak_api_key_compat;
 mod events;
 mod external_agent_config;
@@ -1012,6 +1013,7 @@ impl AppServerSession {
             /*session_start_source*/ None,
             /*remote_cwd_override*/ None,
             /*selected_profile*/ None,
+            /*host_project_cwd*/ None,
         )
         .await
     }
@@ -1023,6 +1025,7 @@ impl AppServerSession {
         session_start_source: Option<ThreadStartSource>,
         remote_cwd_override: Option<&std::path::Path>,
         selected_profile: Option<&PermissionProfileSelection>,
+        host_project_cwd: Option<&std::path::Path>,
     ) -> Result<AppServerStartedThread> {
         if self.thread_params_mode.settings_owner() == ThreadSettingsOwner::Server
             && selected_profile.is_some()
@@ -1063,12 +1066,27 @@ impl AppServerSession {
             self.thread_tool_transport().configure(&mut params);
         }
         let request_handle = self.request_handle();
-        let (response, history_support, task_tools_available) =
-            request_thread_start_with_history_fallback(&request_handle, request_id, params)
+        let project = if self.thread_params_mode == ThreadParamsMode::Cloud {
+            match host_project_cwd {
+                Some(cwd) => cloud_project::from_local_cwd(cwd).await,
+                None => None,
+            }
+        } else {
+            None
+        };
+        let started = match project {
+            Some(project) => request_handle
+                .start_cloud_project_thread(request_id, params, project)
                 .await
-                .map_err(|err| {
-                    bootstrap_request_error("thread/start failed during TUI bootstrap", err)
-                })?;
+                .map(|response| (response, ThreadHistorySupport::Paginated, false)),
+            None => {
+                request_thread_start_with_history_fallback(&request_handle, request_id, params)
+                    .await
+            }
+        };
+        let (response, history_support, task_tools_available) = started.map_err(|err| {
+            bootstrap_request_error("thread/start failed during TUI bootstrap", err)
+        })?;
         if history_support == ThreadHistorySupport::LegacyOnly {
             self.history_support = ThreadHistorySupport::LegacyOnly;
         }
diff --git a/codex-rs/tui/src/app_server_session/cloud_project.rs b/codex-rs/tui/src/app_server_session/cloud_project.rs
new file mode 100644
index 0000000000..35cf7df759
--- /dev/null
+++ b/codex-rs/tui/src/app_server_session/cloud_project.rs
@@ -0,0 +1,48 @@
+//! Resolves a host project into credential-free GitHub checkout metadata.
+//! Local paths never become cloud executor cwd values or public wire fields.
+
+use codex_app_server_client::ProjectEnvironment;
+use std::path::Path;
+
+pub(super) async fn from_local_cwd(cwd: &Path) -> Option<ProjectEnvironment> {
+    let origin = codex_git_utils::get_git_origin_url(cwd).await?;
+    github_project(origin.as_str())
+}
+
+fn github_project(origin: &str) -> Option<ProjectEnvironment> {
+    // A relative local path such as github.com/org/repo is not a network origin.
+    if !origin.contains("://")
+        && !origin.split_once(':').is_some_and(|(host, _)| {
+            host.rsplit('@')
+                .next()
+                .is_some_and(|host| host.eq_ignore_ascii_case("github.com"))
+        })
+    {
+        return None;
+    }
+    let mut canonical = codex_git_utils::canonicalize_git_remote_url(origin)?;
+    canonical.make_ascii_lowercase();
+    let (host, path) = canonical.split_once('/')?;
+    if !(host == "github.com" || (origin.starts_with("ssh://") && host == "ssh.github.com:443")) {
+        return None;
+    }
+    let (owner, repository) = path.split_once('/')?;
+    if ![owner, repository].iter().all(|part| {
+        !part.is_empty()
+            && !matches!(*part, "." | "..")
+            && part.chars().all(|character| {
+                character.is_ascii_alphanumeric() || matches!(character, '-' | '_' | '.')
+            })
+    }) {
+        return None;
+    }
+    Some(ProjectEnvironment {
+        name: repository.to_owned(),
+        cwd: Some(format!("/workspace/{owner}/{repository}")),
+        origin_urls: vec![format!("https://github.com/{owner}/{repository}")],
+    })
+}
+
+#[cfg(test)]
+#[path = "cloud_project_tests.rs"]
+mod tests;
diff --git a/codex-rs/tui/src/app_server_session/cloud_project_tests.rs b/codex-rs/tui/src/app_server_session/cloud_project_tests.rs
new file mode 100644
index 0000000000..317a122b5b
--- /dev/null
+++ b/codex-rs/tui/src/app_server_session/cloud_project_tests.rs
@@ -0,0 +1,153 @@
+#![cfg(test)]
+
+use super::*;
+use pretty_assertions::assert_eq;
+
+#[test]
+fn github_origins_are_normalized_without_credentials_or_query_strings() {
+    for origin in [
+        "git@github.com:Org/Repo.git",
+        "ssh://git@github.com/Org/Repo.git",
+        "https://user:password@github.com/Org/Repo.git?token=secret#fragment",
+    ] {
+        let project = github_project(origin).unwrap();
+        assert_eq!(
+            (project.name, project.origin_urls),
+            (
+                "repo".to_owned(),
+                vec!["https://github.com/org/repo".to_owned()]
+            ),
+        );
+    }
+}
+
+#[tokio::test]
+async fn cloud_starts_use_each_requests_host_project_without_caching() {
+    use super::super::AppServerSession;
+    use super::super::ThreadParamsMode;
+    use crate::legacy_core::config::ConfigBuilder;
+    use crate::local_settings::LocalSettings;
+    use codex_app_server_client::AppServerClient;
+    use codex_app_server_client::CloudClient;
+    use codex_app_server_client::CloudOperation;
+    use codex_app_server_protocol::ClientRequest;
+    use codex_app_server_protocol::JSONRPCErrorError;
+
+    let home = tempfile::tempdir().unwrap();
+    let config = ConfigBuilder::default()
+        .codex_home(home.path().to_path_buf())
+        .build()
+        .await
+        .unwrap();
+    let local_settings = LocalSettings::from(&config);
+    let first = tempfile::tempdir().unwrap();
+    let second = tempfile::tempdir().unwrap();
+    let misleading = tempfile::tempdir().unwrap();
+    for (directory, origin) in [
+        (first.path(), "git@github.com:org/first.git"),
+        (second.path(), "ssh://git@ssh.github.com:443/Org/Second.git"),
+        (
+            misleading.path(),
+            "https://example.com?target=@github.com/org/wrong",
+        ),
+    ] {
+        for args in [
+            vec!["init", "--quiet"],
+            vec!["remote", "add", "origin", origin],
+        ] {
+            assert!(
+                tokio::process::Command::new("git")
+                    .args(args)
+                    .current_dir(directory)
+                    .status()
+                    .await
+                    .unwrap()
+                    .success()
+            );
+        }
+    }
+    let nested = first.path().join("src");
+    std::fs::create_dir(&nested).unwrap();
+    let projectless = tempfile::tempdir().unwrap();
+    let (client, mut commands, _events) = CloudClient::channel(/*capacity*/ 1);
+    let mut session = AppServerSession::new(
+        crate::backend_id::BackendId::new(),
+        AppServerClient::Cloud(client),
+        ThreadParamsMode::Cloud,
+    );
+    let worker = tokio::spawn(async move {
+        for expected in [Some("first"), Some("second"), None, None, None, None] {
+            let command = commands.recv().await.unwrap();
+            match (expected, command.operation) {
+                (
+                    Some(expected),
+                    CloudOperation::StartProjectThread {
+                        params, project, ..
+                    },
+                ) => {
+                    assert_eq!(project.name, expected);
+                    assert_eq!(project.cwd, Some(format!("/workspace/org/{expected}")));
+                    assert_eq!(params.cwd, None);
+                    assert_eq!(params.runtime_workspace_roots, None);
+                    assert_eq!(
+                        project.origin_urls,
+                        vec![format!("https://github.com/org/{expected}")]
+                    );
+                }
+                (None, CloudOperation::Request(request)) => {
+                    assert!(matches!(*request, ClientRequest::ThreadStart { .. }))
+                }
+                _ => panic!("incorrect project routing"),
+            }
+            command
+                .response
+                .send(Ok(Err(JSONRPCErrorError {
+                    code: -32000,
+                    message: "checkout failed".into(),
+                    data: None,
+                })))
+                .unwrap();
+        }
+    });
+    for (mode, host) in [
+        (ThreadParamsMode::Cloud, Some(nested.as_path())),
+        (ThreadParamsMode::Cloud, Some(second.path())),
+        (ThreadParamsMode::Cloud, Some(misleading.path())),
+        (ThreadParamsMode::Cloud, Some(projectless.path())),
+        (ThreadParamsMode::Cloud, None),
+        (ThreadParamsMode::Remote, Some(first.path())),
+    ] {
+        session.thread_params_mode = mode;
+        let result = session
+            .start_thread_with_session_start_source(
+                &local_settings,
+                &config,
+                /*session_start_source*/ None,
+                /*remote_cwd_override*/ None,
+                /*selected_profile*/ None,
+                host,
+            )
+            .await;
+        assert!(result.unwrap_err().to_string().contains("checkout failed"));
+    }
+    worker.await.unwrap();
+}
+
+#[test]
+fn unsupported_or_non_repository_origins_leave_the_thread_blank() {
+    for origin in [
+        "/local/repository",
+        "github.com/org/repo",
+        "https://git.example.com/org/repo",
+        "http://ssh.github.com:443/org/repo.git",
+        "ssh://git@ssh.github.com:8443/org/repo.git",
+        "https://github.com/org",
+        "https://github.com/org/repo/tree/main",
+        "https://github.com/org/repo%2fother",
+    ] {
+        assert!(
+            github_project(origin).is_none(),
+            "unexpected origin: {origin}"
+        );
+    }
+}
diff --git a/codex-rs/tui/src/app_server_session/prompt_history_tests.rs b/codex-rs/tui/src/app_server_session/prompt_history_tests.rs
index 6743f85a16..fb0b0d7d5a 100644
--- a/codex-rs/tui/src/app_server_session/prompt_history_tests.rs
+++ b/codex-rs/tui/src/app_server_session/prompt_history_tests.rs
@@ -60,6 +60,7 @@ async fn lifecycle_metadata_uses_local_prompt_history() -> Result<()> {
                 /*session_start_source*/ None,
                 /*remote_cwd_override*/ None,
                 /*selected_profile*/ None,
+                /*host_project_cwd*/ None,
             )
             .await?;
         assert_eq!(started.session.message_history, expected);