diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadForkParams.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadForkParams.json
index 9d2f834dd..d9a543e93 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadForkParams.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadForkParams.json
@@ -1,6 +1,10 @@
 {
   "$schema": "http://json-schema.org/draft-07/schema#",
   "definitions": {
+    "AbsolutePathBuf": {
+      "description": "A path that is guaranteed to be absolute and normalized (though it is not guaranteed to be canonicalized or exist on the filesystem).\n\nIMPORTANT: When deserializing an `AbsolutePathBuf`, a base path must be set using [AbsolutePathBufGuard::new]. If no base path is set, the deserialization will fail unless the path being deserialized is already absolute.",
+      "type": "string"
+    },
     "ApprovalsReviewer": {
       "description": "Configures who approval requests are routed to for review. Examples include sandbox escapes, blocked network access, MCP approval prompts, and ARC escalations. Defaults to `user`. `auto_review` uses a carefully prompted subagent to gather relevant context and apply a risk-based decision framework before approving or denying the request. The legacy value `guardian_subagent` is accepted for compatibility.",
       "enum": [
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadResumeParams.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadResumeParams.json
index a6abcc566..dc5ef5cda 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadResumeParams.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadResumeParams.json
@@ -1,6 +1,10 @@
 {
   "$schema": "http://json-schema.org/draft-07/schema#",
   "definitions": {
+    "AbsolutePathBuf": {
+      "description": "A path that is guaranteed to be absolute and normalized (though it is not guaranteed to be canonicalized or exist on the filesystem).\n\nIMPORTANT: When deserializing an `AbsolutePathBuf`, a base path must be set using [AbsolutePathBufGuard::new]. If no base path is set, the deserialization will fail unless the path being deserialized is already absolute.",
+      "type": "string"
+    },
     "AgentMessageInputContent": {
       "oneOf": [
         {
diff --git a/codex-rs/app-server-protocol/src/protocol/v2/thread.rs b/codex-rs/app-server-protocol/src/protocol/v2/thread.rs
index 9dab60a04..486e121cf 100644
--- a/codex-rs/app-server-protocol/src/protocol/v2/thread.rs
+++ b/codex-rs/app-server-protocol/src/protocol/v2/thread.rs
@@ -107,11 +107,10 @@ pub struct ThreadStartParams {
     pub service_tier: Option<Option<String>>,
     #[ts(optional = nullable)]
     pub cwd: Option<String>,
-    /// Replace the thread's runtime workspace roots. Relative paths are
-    /// resolved against the effective cwd for the thread.
+    /// Replace the thread's runtime workspace roots. Paths must be absolute.
     #[experimental("thread/start.runtimeWorkspaceRoots")]
     #[ts(optional = nullable)]
-    pub runtime_workspace_roots: Option<Vec<PathBuf>>,
+    pub runtime_workspace_roots: Option<Vec<AbsolutePathBuf>>,
     #[experimental(nested)]
     #[ts(optional = nullable)]
     pub approval_policy: Option<AskForApproval>,
@@ -358,11 +357,10 @@ pub struct ThreadResumeParams {
     pub service_tier: Option<Option<String>>,
     #[ts(optional = nullable)]
     pub cwd: Option<String>,
-    /// Replace the thread's runtime workspace roots. Relative paths are
-    /// resolved against the effective cwd for the thread.
+    /// Replace the thread's runtime workspace roots. Paths must be absolute.
     #[experimental("thread/resume.runtimeWorkspaceRoots")]
     #[ts(optional = nullable)]
-    pub runtime_workspace_roots: Option<Vec<PathBuf>>,
+    pub runtime_workspace_roots: Option<Vec<AbsolutePathBuf>>,
     #[experimental(nested)]
     #[ts(optional = nullable)]
     pub approval_policy: Option<AskForApproval>,
@@ -509,11 +507,10 @@ pub struct ThreadForkParams {
     pub service_tier: Option<Option<String>>,
     #[ts(optional = nullable)]
     pub cwd: Option<String>,
-    /// Replace the thread's runtime workspace roots. Relative paths are
-    /// resolved against the effective cwd for the thread.
+    /// Replace the thread's runtime workspace roots. Paths must be absolute.
     #[experimental("thread/fork.runtimeWorkspaceRoots")]
     #[ts(optional = nullable)]
-    pub runtime_workspace_roots: Option<Vec<PathBuf>>,
+    pub runtime_workspace_roots: Option<Vec<AbsolutePathBuf>>,
     #[experimental(nested)]
     #[ts(optional = nullable)]
     pub approval_policy: Option<AskForApproval>,
diff --git a/codex-rs/app-server-protocol/src/protocol/v2/turn.rs b/codex-rs/app-server-protocol/src/protocol/v2/turn.rs
index f9bfe2147..3bac7bf7e 100644
--- a/codex-rs/app-server-protocol/src/protocol/v2/turn.rs
+++ b/codex-rs/app-server-protocol/src/protocol/v2/turn.rs
@@ -88,11 +88,10 @@ pub struct TurnStartParams {
     #[ts(optional = nullable)]
     pub cwd: Option<PathBuf>,
     /// Replace the thread's runtime workspace roots for this turn and
-    /// subsequent turns. Relative paths are resolved against the effective
-    /// cwd for the turn.
+    /// subsequent turns. Paths must be absolute.
     #[experimental("turn/start.runtimeWorkspaceRoots")]
     #[ts(optional = nullable)]
-    pub runtime_workspace_roots: Option<Vec<PathBuf>>,
+    pub runtime_workspace_roots: Option<Vec<AbsolutePathBuf>>,
     /// Override the approval policy for this turn and subsequent turns.
     #[experimental(nested)]
     #[ts(optional = nullable)]
diff --git a/codex-rs/app-server/README.md b/codex-rs/app-server/README.md
index 4e06dc16e..a12144238 100644
--- a/codex-rs/app-server/README.md
+++ b/codex-rs/app-server/README.md
@@ -130,7 +130,7 @@ Example with notification opt-out:
 
 ## API Overview
 
-- `thread/start` — create a new thread; emits `thread/started` (including the current `thread.status`) and auto-subscribes you to turn/item events for that thread. When the request includes a `cwd` and the resolved sandbox is `workspace-write` or full access, app-server also marks that project as trusted in the user `config.toml`. Pass `sessionStartSource: "clear"` when starting a replacement thread after clearing the current session so `SessionStart` hooks receive `source: "clear"` instead of the default `"startup"`. Experimental `runtimeWorkspaceRoots` replaces the thread-scoped runtime workspace roots used to materialize `:workspace_roots`; relative paths resolve against the effective thread cwd. For permissions, prefer experimental `permissions` profile selection by id; the legacy `sandbox` shorthand is still accepted but cannot be combined with `permissions`. Experimental `environments` selects the sticky execution environments for turns on the thread; omit it to use the server default, pass `[]` to disable environments, or pass explicit environment ids with per-environment `cwd`.
+- `thread/start` — create a new thread; emits `thread/started` (including the current `thread.status`) and auto-subscribes you to turn/item events for that thread. When the request includes a `cwd` and the resolved sandbox is `workspace-write` or full access, app-server also marks that project as trusted in the user `config.toml`. Pass `sessionStartSource: "clear"` when starting a replacement thread after clearing the current session so `SessionStart` hooks receive `source: "clear"` instead of the default `"startup"`. Experimental `runtimeWorkspaceRoots` replaces the thread-scoped runtime workspace roots used to materialize `:workspace_roots`; paths must be absolute. For permissions, prefer experimental `permissions` profile selection by id; the legacy `sandbox` shorthand is still accepted but cannot be combined with `permissions`. Experimental `environments` selects the sticky execution environments for turns on the thread; omit it to use the server default, pass `[]` to disable environments, or pass explicit environment ids with per-environment `cwd`.
 - `thread/resume` — reopen an existing thread by id so subsequent `turn/start` calls append to it. Accepts the same permission override rules as `thread/start`.
 - `thread/fork` — fork an existing thread into a new thread id by copying the stored history; if the source thread is currently mid-turn, the fork records the same interruption marker as `turn/interrupt` instead of inheriting an unmarked partial turn suffix. The returned `thread.forkedFromId` points at the source thread when known. Accepts `ephemeral: true` for an in-memory temporary fork, emits `thread/started` (including the current `thread.status`), and auto-subscribes you to turn/item events for the new thread. Experimental clients can pass `excludeTurns: true` when they plan to page fork history via `thread/turns/list` instead of receiving the full turn array immediately. Accepts the same permission override rules as `thread/start`.
 - `thread/start`, `thread/resume`, and `thread/fork` responses include the legacy `sandbox` compatibility projection. Experimental clients can read `runtimeWorkspaceRoots` for the thread-scoped runtime roots and `activePermissionProfile` for the named or implicit built-in profile identity/provenance when known.
@@ -158,7 +158,7 @@ Example with notification opt-out:
 - `thread/shellCommand` — run a user-initiated `!` shell command against a thread; this runs unsandboxed with full access rather than inheriting the thread sandbox policy. Returns `{}` immediately while progress streams through standard turn/item notifications and any active turn receives the formatted output in its message stream.
 - `thread/backgroundTerminals/clean` — terminate all running background terminals for a thread (experimental; requires `capabilities.experimentalApi`); returns `{}` when the cleanup request is accepted.
 - `thread/rollback` — drop the last N turns from the agent’s in-memory context and persist a rollback marker in the rollout so future resumes see the pruned history; returns the updated `thread` (with `turns` populated) on success.
-- `turn/start` — add user input to a thread and begin Codex generation; responds with the initial `turn` object and streams `turn/started`, `item/*`, and `turn/completed` notifications. `clientUserMessageId` is optional; when supplied, the corresponding `userMessage` item echoes it as `clientId`. Experimental `runtimeWorkspaceRoots` replaces the thread-scoped runtime workspace roots used to materialize `:workspace_roots`; relative paths resolve against the effective turn cwd. Prefer experimental `permissions` profile selection by id for permission overrides; the legacy `sandboxPolicy` field is still accepted but cannot be combined with `permissions`. For `collaborationMode`, `settings.developer_instructions: null` means "use built-in instructions for the selected mode".
+- `turn/start` — add user input to a thread and begin Codex generation; responds with the initial `turn` object and streams `turn/started`, `item/*`, and `turn/completed` notifications. `clientUserMessageId` is optional; when supplied, the corresponding `userMessage` item echoes it as `clientId`. Experimental `runtimeWorkspaceRoots` replaces the thread-scoped runtime workspace roots used to materialize `:workspace_roots`; paths must be absolute. Prefer experimental `permissions` profile selection by id for permission overrides; the legacy `sandboxPolicy` field is still accepted but cannot be combined with `permissions`. For `collaborationMode`, `settings.developer_instructions: null` means "use built-in instructions for the selected mode".
 - `thread/inject_items` — append raw Responses API items to a loaded thread’s model-visible history without starting a user turn; returns `{}` on success.
 - `turn/steer` — add user input to an already in-flight regular turn without starting a new turn; returns the active `turnId` that accepted the input. `clientUserMessageId` is optional; when supplied, the corresponding `userMessage` item echoes it as `clientId`. Review and manual compaction turns reject `turn/steer`.
 - `turn/interrupt` — request cancellation of an in-flight turn by `(thread_id, turn_id)`; success is an empty `{}` response and the turn finishes with `status: "interrupted"`.
diff --git a/codex-rs/app-server/src/request_processors.rs b/codex-rs/app-server/src/request_processors.rs
index 00468b0a9..bfcf328c4 100644
--- a/codex-rs/app-server/src/request_processors.rs
+++ b/codex-rs/app-server/src/request_processors.rs
@@ -513,6 +513,24 @@ use crate::thread_state::ThreadStateManager;
 use token_usage_replay::latest_token_usage_turn_id_from_rollout_items;
 use token_usage_replay::send_thread_token_usage_update_to_connection;
 
+fn resolve_request_cwd(cwd: Option<PathBuf>) -> Result<Option<AbsolutePathBuf>, JSONRPCErrorError> {
+    cwd.map(|cwd| {
+        AbsolutePathBuf::relative_to_current_dir(path_utils::normalize_for_native_workdir(cwd))
+            .map_err(|err| invalid_request(format!("invalid cwd: {err}")))
+    })
+    .transpose()
+}
+
+fn resolve_runtime_workspace_roots(workspace_roots: Vec<AbsolutePathBuf>) -> Vec<AbsolutePathBuf> {
+    let mut resolved_roots = Vec::new();
+    for root in workspace_roots {
+        if !resolved_roots.iter().any(|existing| existing == &root) {
+            resolved_roots.push(root);
+        }
+    }
+    resolved_roots
+}
+
 mod config_errors;
 mod request_errors;
 mod thread_goal_processor;
diff --git a/codex-rs/app-server/src/request_processors/thread_processor.rs b/codex-rs/app-server/src/request_processors/thread_processor.rs
index efff8e7cd..eab606bf6 100644
--- a/codex-rs/app-server/src/request_processors/thread_processor.rs
+++ b/codex-rs/app-server/src/request_processors/thread_processor.rs
@@ -56,17 +56,7 @@ fn collect_resume_override_mismatches(
         }
     }
     if let Some(requested_runtime_workspace_roots) = request.runtime_workspace_roots.as_ref() {
-        let base_cwd = request
-            .cwd
-            .as_deref()
-            .map(|cwd| {
-                AbsolutePathBuf::resolve_path_against_base(cwd, config_snapshot.cwd.as_path())
-            })
-            .unwrap_or_else(|| config_snapshot.cwd.clone());
-        let requested_runtime_workspace_roots = requested_runtime_workspace_roots
-            .iter()
-            .map(|path| AbsolutePathBuf::resolve_path_against_base(path, base_cwd.as_path()))
-            .collect::<Vec<_>>();
+        let requested_runtime_workspace_roots = requested_runtime_workspace_roots.to_vec();
         if requested_runtime_workspace_roots != config_snapshot.workspace_roots {
             mismatch_details.push(format!(
                 "runtime_workspace_roots requested={requested_runtime_workspace_roots:?} active={:?}",
@@ -846,6 +836,7 @@ impl ThreadRequestProcessor {
             ));
         }
         let environment_selections = self.parse_environment_selections(environments)?;
+        let runtime_workspace_roots = runtime_workspace_roots.map(resolve_runtime_workspace_roots);
         let mut typesafe_overrides = self.build_thread_config_overrides(
             model,
             model_provider,
@@ -1215,7 +1206,7 @@ impl ThreadRequestProcessor {
         model_provider: Option<String>,
         service_tier: Option<Option<String>>,
         cwd: Option<String>,
-        runtime_workspace_roots: Option<Vec<PathBuf>>,
+        runtime_workspace_roots: Option<Vec<AbsolutePathBuf>>,
         approval_policy: Option<codex_app_server_protocol::AskForApproval>,
         approvals_reviewer: Option<codex_app_server_protocol::ApprovalsReviewer>,
         sandbox: Option<SandboxMode>,
@@ -2483,6 +2474,7 @@ impl ThreadRequestProcessor {
         };
 
         let history_cwd = thread_history.session_cwd();
+        let runtime_workspace_roots = runtime_workspace_roots.map(resolve_runtime_workspace_roots);
         let mut typesafe_overrides = self.build_thread_config_overrides(
             model,
             model_provider,
@@ -3201,6 +3193,7 @@ impl ThreadRequestProcessor {
         } else {
             Some(cli_overrides)
         };
+        let runtime_workspace_roots = runtime_workspace_roots.map(resolve_runtime_workspace_roots);
         let mut typesafe_overrides = self.build_thread_config_overrides(
             model,
             model_provider,
diff --git a/codex-rs/app-server/src/request_processors/turn_processor.rs b/codex-rs/app-server/src/request_processors/turn_processor.rs
index 85342235c..ce98a2e8e 100644
--- a/codex-rs/app-server/src/request_processors/turn_processor.rs
+++ b/codex-rs/app-server/src/request_processors/turn_processor.rs
@@ -18,28 +18,6 @@ pub(crate) struct TurnRequestProcessor {
     skills_watcher: Arc<SkillsWatcher>,
 }
 
-fn resolve_runtime_workspace_roots(
-    workspace_roots: Vec<PathBuf>,
-    base_cwd: &AbsolutePathBuf,
-) -> Vec<AbsolutePathBuf> {
-    let mut resolved_roots = Vec::new();
-    for path in workspace_roots {
-        let root = AbsolutePathBuf::resolve_path_against_base(path, base_cwd.as_path());
-        if !resolved_roots.iter().any(|existing| existing == &root) {
-            resolved_roots.push(root);
-        }
-    }
-    resolved_roots
-}
-
-fn resolve_request_cwd(cwd: Option<PathBuf>) -> Result<Option<AbsolutePathBuf>, JSONRPCErrorError> {
-    cwd.map(|cwd| {
-        AbsolutePathBuf::relative_to_current_dir(path_utils::normalize_for_native_workdir(cwd))
-            .map_err(|err| invalid_request(format!("invalid cwd: {err}")))
-    })
-    .transpose()
-}
-
 fn map_additional_context(
     additional_context: Option<HashMap<String, AdditionalContextEntry>>,
 ) -> BTreeMap<String, CoreAdditionalContextEntry> {
@@ -66,7 +44,7 @@ fn map_additional_context(
 struct ThreadSettingsBuildParams {
     method: &'static str,
     cwd: Option<AbsolutePathBuf>,
-    runtime_workspace_roots: Option<Vec<PathBuf>>,
+    runtime_workspace_roots: Option<Vec<AbsolutePathBuf>>,
     approval_policy: Option<codex_app_server_protocol::AskForApproval>,
     approvals_reviewer: Option<codex_app_server_protocol::ApprovalsReviewer>,
     sandbox_policy: Option<codex_app_server_protocol::SandboxPolicy>,
@@ -533,7 +511,7 @@ impl TurnRequestProcessor {
         // `thread/settings/update` only acknowledges that the update was queued.
         // Clients that send dependent partial updates should wait for
         // `thread/settings/updated` or combine the fields in one request.
-        let snapshot = if permissions.is_some() || runtime_workspace_roots_request.is_some() {
+        let snapshot = if permissions.is_some() {
             Some(thread.config_snapshot().await)
         } else {
             None
@@ -552,22 +530,8 @@ impl TurnRequestProcessor {
             || collaboration_mode.is_some()
             || personality.is_some();
 
-        let runtime_workspace_roots = if let Some(workspace_roots) =
-            runtime_workspace_roots_request.clone()
-        {
-            let Some(snapshot) = snapshot.as_ref() else {
-                return Err(internal_error(format!(
-                    "{method} runtime workspace roots missing thread snapshot"
-                )));
-            };
-            let base_cwd = cwd
-                .as_ref()
-                .map(|cwd| AbsolutePathBuf::resolve_path_against_base(cwd, snapshot.cwd.as_path()))
-                .unwrap_or_else(|| snapshot.cwd.clone());
-            Some(resolve_runtime_workspace_roots(workspace_roots, &base_cwd))
-        } else {
-            None
-        };
+        let runtime_workspace_roots =
+            runtime_workspace_roots_request.map(resolve_runtime_workspace_roots);
         let approval_policy =
             approval_policy.map(codex_app_server_protocol::AskForApproval::to_core);
         let approvals_reviewer =
@@ -582,15 +546,11 @@ impl TurnRequestProcessor {
                 };
                 let overrides = ConfigOverrides {
                     cwd: cwd.as_ref().map(AbsolutePathBuf::to_path_buf),
-                    workspace_roots: Some(runtime_workspace_roots_request.clone().unwrap_or_else(
-                        || {
-                            snapshot
-                                .workspace_roots
-                                .iter()
-                                .map(AbsolutePathBuf::to_path_buf)
-                                .collect()
-                        },
-                    )),
+                    workspace_roots: Some(
+                        runtime_workspace_roots
+                            .clone()
+                            .unwrap_or_else(|| snapshot.workspace_roots.clone()),
+                    ),
                     default_permissions: Some(permissions),
                     codex_linux_sandbox_exe: self.arg0_paths.codex_linux_sandbox_exe.clone(),
                     main_execve_wrapper_exe: self.arg0_paths.main_execve_wrapper_exe.clone(),
diff --git a/codex-rs/app-server/tests/suite/v2/thread_resume.rs b/codex-rs/app-server/tests/suite/v2/thread_resume.rs
index 4ae68b0e7..582177ee7 100644
--- a/codex-rs/app-server/tests/suite/v2/thread_resume.rs
+++ b/codex-rs/app-server/tests/suite/v2/thread_resume.rs
@@ -366,7 +366,10 @@ async fn turn_start_updates_runtime_workspace_roots_for_loaded_thread() -> Resul
                 text: "Hello".to_string(),
                 text_elements: Vec::new(),
             }],
-            runtime_workspace_roots: Some(vec![extra_root.clone(), extra_root.join(".")]),
+            runtime_workspace_roots: Some(vec![
+                AbsolutePathBuf::from_absolute_path(&extra_root)?,
+                AbsolutePathBuf::from_absolute_path(extra_root.join("."))?,
+            ]),
             ..Default::default()
         })
         .await?;
diff --git a/codex-rs/app-server/tests/suite/v2/thread_start.rs b/codex-rs/app-server/tests/suite/v2/thread_start.rs
index a2da95545..5954342b9 100644
--- a/codex-rs/app-server/tests/suite/v2/thread_start.rs
+++ b/codex-rs/app-server/tests/suite/v2/thread_start.rs
@@ -197,15 +197,15 @@ async fn thread_start_creates_thread_and_emits_started() -> Result<()> {
 }
 
 #[tokio::test]
-async fn thread_start_resolves_runtime_workspace_roots_against_cwd() -> Result<()> {
+async fn thread_start_accepts_absolute_runtime_workspace_roots() -> Result<()> {
     let server = create_mock_responses_server_repeating_assistant("Done").await;
     let codex_home = TempDir::new()?;
     create_config_toml_without_approval_policy(codex_home.path(), &server.uri())?;
 
     let cwd_tmp = TempDir::new()?;
     let cwd = cwd_tmp.path().to_path_buf();
-    let relative_root = PathBuf::from("extra-root");
-    std::fs::create_dir_all(cwd.join(&relative_root))?;
+    let extra_root = cwd.join("extra-root");
+    std::fs::create_dir_all(&extra_root)?;
 
     let mut mcp = TestAppServer::new(codex_home.path()).await?;
     timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
@@ -213,7 +213,7 @@ async fn thread_start_resolves_runtime_workspace_roots_against_cwd() -> Result<(
     let req_id = mcp
         .send_thread_start_request(ThreadStartParams {
             cwd: Some(cwd.to_string_lossy().to_string()),
-            runtime_workspace_roots: Some(vec![relative_root.clone()]),
+            runtime_workspace_roots: Some(vec![extra_root.abs()]),
             ..Default::default()
         })
         .await?;
@@ -230,10 +230,7 @@ async fn thread_start_resolves_runtime_workspace_roots_against_cwd() -> Result<(
     } = to_response::<ThreadStartResponse>(resp)?;
 
     assert_eq!(response_cwd, cwd.abs());
-    assert_eq!(
-        runtime_workspace_roots,
-        vec![cwd_tmp.path().join(relative_root).abs()]
-    );
+    assert_eq!(runtime_workspace_roots, vec![extra_root.abs()]);
 
     Ok(())
 }
diff --git a/codex-rs/app-server/tests/suite/v2/turn_start.rs b/codex-rs/app-server/tests/suite/v2/turn_start.rs
index b4da5cdde..aed3c5869 100644
--- a/codex-rs/app-server/tests/suite/v2/turn_start.rs
+++ b/codex-rs/app-server/tests/suite/v2/turn_start.rs
@@ -2449,6 +2449,8 @@ async fn turn_start_permission_profile_rebinds_runtime_workspace_roots_between_t
     std::fs::create_dir(&new_root)?;
     let old_root_text = old_root.to_string_lossy().into_owned();
     let new_root_text = new_root.to_string_lossy().into_owned();
+    let old_root = codex_utils_absolute_path::AbsolutePathBuf::from_absolute_path(old_root)?;
+    let new_root = codex_utils_absolute_path::AbsolutePathBuf::from_absolute_path(new_root)?;
 
     let server = responses::start_mock_server().await;
     let response_mock = responses::mount_sse_sequence(
diff --git a/codex-rs/core/src/config/mod.rs b/codex-rs/core/src/config/mod.rs
index b74f2feef..e319f3b39 100644
--- a/codex-rs/core/src/config/mod.rs
+++ b/codex-rs/core/src/config/mod.rs
@@ -2245,9 +2245,9 @@ pub struct ConfigOverrides {
     pub bypass_hook_trust: Option<bool>,
     /// Additional directories that should be treated as writable roots for this session.
     pub additional_writable_roots: Vec<PathBuf>,
-    /// Explicit runtime workspace roots for this session. When set, this is
-    /// the full runtime root list rather than an additive override.
-    pub workspace_roots: Option<Vec<PathBuf>>,
+    /// Explicit absolute runtime workspace roots for this session. When set,
+    /// this is the full runtime root list rather than an additive override.
+    pub workspace_roots: Option<Vec<AbsolutePathBuf>>,
 }
 
 fn dedupe_absolute_paths(paths: &mut Vec<AbsolutePathBuf>) {
@@ -2821,12 +2821,7 @@ impl Config {
             || !requested_additional_writable_roots.is_empty()
             || legacy_workspace_roots_explicit;
         let mut workspace_roots = match workspace_roots_override {
-            Some(workspace_roots) => workspace_roots
-                .into_iter()
-                .map(|path| {
-                    AbsolutePathBuf::resolve_path_against_base(path, resolved_cwd.as_path())
-                })
-                .collect(),
+            Some(workspace_roots) => workspace_roots,
             None => {
                 let mut workspace_roots = vec![resolved_cwd.clone()];
                 workspace_roots.extend(requested_additional_writable_roots.clone());
diff --git a/codex-rs/exec/src/lib.rs b/codex-rs/exec/src/lib.rs
index 797e168dc..b8b87a85e 100644
--- a/codex-rs/exec/src/lib.rs
+++ b/codex-rs/exec/src/lib.rs
@@ -1044,13 +1044,7 @@ fn thread_start_params_from_config(config: &Config) -> ThreadStartParams {
         model: config.model.clone(),
         model_provider: Some(config.model_provider_id.clone()),
         cwd: Some(config.cwd.to_string_lossy().to_string()),
-        runtime_workspace_roots: Some(
-            config
-                .workspace_roots
-                .iter()
-                .map(AbsolutePathBuf::to_path_buf)
-                .collect(),
-        ),
+        runtime_workspace_roots: Some(config.workspace_roots.clone()),
         approval_policy: Some(config.permissions.approval_policy.value().into()),
         approvals_reviewer: approvals_reviewer_override_from_config(config),
         sandbox: sandbox.flatten(),
@@ -1075,13 +1069,7 @@ fn thread_resume_params_from_config(config: &Config, thread_id: String) -> Threa
         model: config.model.clone(),
         model_provider: Some(config.model_provider_id.clone()),
         cwd: Some(config.cwd.to_string_lossy().to_string()),
-        runtime_workspace_roots: Some(
-            config
-                .workspace_roots
-                .iter()
-                .map(AbsolutePathBuf::to_path_buf)
-                .collect(),
-        ),
+        runtime_workspace_roots: Some(config.workspace_roots.clone()),
         approval_policy: Some(config.permissions.approval_policy.value().into()),
         approvals_reviewer: approvals_reviewer_override_from_config(config),
         sandbox: sandbox.flatten(),
diff --git a/codex-rs/tui/src/app_server_session.rs b/codex-rs/tui/src/app_server_session.rs
index ccd6304d7..438ee21ca 100644
--- a/codex-rs/tui/src/app_server_session.rs
+++ b/codex-rs/tui/src/app_server_session.rs
@@ -708,12 +708,7 @@ impl AppServerSession {
                     additional_context: None,
                     environments: None,
                     cwd: Some(cwd),
-                    runtime_workspace_roots: Some(
-                        workspace_roots
-                            .iter()
-                            .map(AbsolutePathBuf::to_path_buf)
-                            .collect(),
-                    ),
+                    runtime_workspace_roots: Some(workspace_roots.to_vec()),
                     approval_policy: Some(approval_policy),
                     approvals_reviewer: Some(approvals_reviewer.into()),
                     sandbox_policy,
@@ -1403,13 +1398,7 @@ fn thread_start_params_from_config(
         model_provider: thread_params_mode.model_provider_from_config(config),
         service_tier: service_tier_override_from_config(config),
         cwd: thread_cwd_from_config(config, thread_params_mode, remote_cwd_override),
-        runtime_workspace_roots: Some(
-            config
-                .workspace_roots
-                .iter()
-                .map(AbsolutePathBuf::to_path_buf)
-                .collect(),
-        ),
+        runtime_workspace_roots: Some(config.workspace_roots.clone()),
         approval_policy: Some(config.permissions.approval_policy.value().into()),
         approvals_reviewer: approvals_reviewer_override_from_config(config),
         sandbox,
@@ -1444,13 +1433,7 @@ fn thread_resume_params_from_config(
         model_provider: thread_params_mode.model_provider_from_config(&config),
         service_tier: service_tier_override_from_config(&config),
         cwd: thread_cwd_from_config(&config, thread_params_mode, remote_cwd_override),
-        runtime_workspace_roots: Some(
-            config
-                .workspace_roots
-                .iter()
-                .map(AbsolutePathBuf::to_path_buf)
-                .collect(),
-        ),
+        runtime_workspace_roots: Some(config.workspace_roots.clone()),
         approval_policy: Some(config.permissions.approval_policy.value().into()),
         approvals_reviewer: approvals_reviewer_override_from_config(&config),
         sandbox,
@@ -1482,13 +1465,7 @@ fn thread_fork_params_from_config(
         model_provider: thread_params_mode.model_provider_from_config(&config),
         service_tier: service_tier_override_from_config(&config),
         cwd: thread_cwd_from_config(&config, thread_params_mode, remote_cwd_override),
-        runtime_workspace_roots: Some(
-            config
-                .workspace_roots
-                .iter()
-                .map(AbsolutePathBuf::to_path_buf)
-                .collect(),
-        ),
+        runtime_workspace_roots: Some(config.workspace_roots.clone()),
         approval_policy: Some(config.permissions.approval_policy.value().into()),
         approvals_reviewer: approvals_reviewer_override_from_config(&config),
         sandbox,
@@ -1885,13 +1862,7 @@ mod tests {
         assert_eq!(params.cwd, Some(config.cwd.to_string_lossy().to_string()));
         assert_eq!(
             params.runtime_workspace_roots,
-            Some(
-                config
-                    .workspace_roots
-                    .iter()
-                    .map(AbsolutePathBuf::to_path_buf)
-                    .collect()
-            )
+            Some(config.workspace_roots.clone())
         );
         assert_eq!(params.sandbox, None);
         assert_eq!(
@@ -2009,13 +1980,7 @@ mod tests {
             &config.permissions.effective_permission_profile(),
             config.cwd.as_path(),
         );
-        let expected_runtime_workspace_roots = Some(
-            config
-                .workspace_roots
-                .iter()
-                .map(AbsolutePathBuf::to_path_buf)
-                .collect::<Vec<_>>(),
-        );
+        let expected_runtime_workspace_roots = Some(config.workspace_roots.clone());
 
         let start = thread_start_params_from_config(
             &config,