diff --git a/server/src/llm/oauth.rs b/server/src/llm/oauth.rs
index 38616ee7..76ec4ee5 100644
--- a/server/src/llm/oauth.rs
+++ b/server/src/llm/oauth.rs
@@ -114,6 +114,11 @@ pub struct PoolAccount {
     /// Whether the server has observed a rate-limit response for this account.
     #[serde(default)]
     pub rate_limited: bool,
+    /// Unix-epoch milliseconds when the rate limit resets, if known.
+    ///
+    /// Used to compute "time until earliest reset" when all accounts are exhausted.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub rate_limit_reset_at: Option<u64>,
 }
 
 /// The multi-account login pool, stored in `~/.claude/oauth_pool.json`.
@@ -173,22 +178,10 @@ pub fn upsert_pool_account(account: PoolAccount) -> Result<(), String> {
     write_pool(&pool)
 }
 
-/// Refresh the OAuth access token using the stored refresh token.
+/// Perform a token refresh HTTP call using `refresh_token`.
 ///
-/// On success, updates `~/.claude/.credentials.json` with the new access
-/// token and expiry, then returns `Ok(())`.
-///
-/// On failure (e.g. refresh token expired), returns an error string.
-pub async fn refresh_access_token() -> Result<(), String> {
-    slog!("[oauth] Attempting to refresh OAuth access token");
-
-    let mut creds = read_credentials()?;
-    let refresh_token = creds.claude_ai_oauth.refresh_token.clone();
-
-    if refresh_token.is_empty() {
-        return Err("No refresh token found. Run `claude login` to authenticate.".to_string());
-    }
-
+/// Returns `(new_access_token, new_expires_at_ms)` on success.
+async fn do_token_refresh(refresh_token: &str) -> Result<(String, u64), String> {
     let client = reqwest::Client::new();
     let resp = client
         .post(TOKEN_ENDPOINT)
@@ -208,7 +201,6 @@ pub async fn refresh_access_token() -> Result<(), String> {
         .map_err(|e| format!("Failed to read refresh response: {e}"))?;
 
     if !status.is_success() {
-        // Try to parse a structured error
         if let Ok(err) = serde_json::from_str::<TokenRefreshError>(&body) {
             let desc = err
                 .error_description
@@ -231,8 +223,30 @@ pub async fn refresh_access_token() -> Result<(), String> {
         .map(|d| d.as_millis() as u64)
         .unwrap_or(0);
 
-    creds.claude_ai_oauth.access_token = token_resp.access_token;
-    creds.claude_ai_oauth.expires_at = now_ms + (token_resp.expires_in * 1000);
+    let expires_at = now_ms + (token_resp.expires_in * 1000);
+    Ok((token_resp.access_token, expires_at))
+}
+
+/// Refresh the OAuth access token using the stored refresh token.
+///
+/// On success, updates `~/.claude/.credentials.json` with the new access
+/// token and expiry, then returns `Ok(())`.
+///
+/// On failure (e.g. refresh token expired), returns an error string.
+pub async fn refresh_access_token() -> Result<(), String> {
+    slog!("[oauth] Attempting to refresh OAuth access token");
+
+    let mut creds = read_credentials()?;
+    let refresh_token = creds.claude_ai_oauth.refresh_token.clone();
+
+    if refresh_token.is_empty() {
+        return Err("No refresh token found. Run `claude login` to authenticate.".to_string());
+    }
+
+    let (new_access_token, new_expires_at) = do_token_refresh(&refresh_token).await?;
+
+    creds.claude_ai_oauth.access_token = new_access_token;
+    creds.claude_ai_oauth.expires_at = new_expires_at;
 
     write_credentials(&creds)?;
 
@@ -244,6 +258,150 @@ pub async fn refresh_access_token() -> Result<(), String> {
     Ok(())
 }
 
+// ── Account pool swap ─────────────────────────────────────────────────────────
+
+/// Select the next non-rate-limited account for swapping, given the current
+/// credentials' refresh token.
+///
+/// Marks the current account (identified by `current_refresh_token`) as
+/// rate-limited with `reset_at_ms`, then returns a clone of the first
+/// non-rate-limited account in the pool.
+///
+/// Returns:
+/// - `Ok(account)` — the next available pool account to switch to
+/// - `Err(msg)` — all accounts are rate-limited (includes earliest reset time
+///   in the message), or the pool has fewer than 2 accounts
+///
+/// This is a pure function exposed for unit testing.  The async
+/// [`swap_to_next_available_account`] calls this and then performs the HTTP
+/// token refresh.
+pub(crate) fn select_next_account_for_swap(
+    pool: &mut AccountPool,
+    current_refresh_token: &str,
+    reset_at_ms: u64,
+) -> Result<PoolAccount, String> {
+    if pool.accounts.len() < 2 {
+        return Err(
+            "No account pool available for automatic account rotation (fewer than 2 accounts)."
+                .to_string(),
+        );
+    }
+
+    // Mark the current account as rate-limited.
+    for account in pool.accounts.values_mut() {
+        if account.refresh_token == current_refresh_token {
+            account.rate_limited = true;
+            account.rate_limit_reset_at = Some(reset_at_ms);
+            break;
+        }
+    }
+
+    // Find the next non-rate-limited account.
+    if let Some(next) = pool.accounts.values().find(|a| !a.rate_limited).cloned() {
+        return Ok(next);
+    }
+
+    // All accounts are rate-limited — compute the earliest reset time.
+    let earliest_reset_ms = pool
+        .accounts
+        .values()
+        .filter_map(|a| a.rate_limit_reset_at)
+        .min();
+
+    let msg = match earliest_reset_ms {
+        Some(ms) => {
+            let reset_secs = (ms / 1000) as i64;
+            let reset_dt =
+                chrono::DateTime::from_timestamp(reset_secs, 0).unwrap_or_else(chrono::Utc::now);
+            let until = reset_dt.signed_duration_since(chrono::Utc::now());
+            let mins = until.num_minutes().max(0);
+            format!(
+                "All OAuth accounts are rate-limited. \
+                 Earliest reset in {} minute{} (at {} UTC).",
+                mins,
+                if mins == 1 { "" } else { "s" },
+                reset_dt.format("%H:%M")
+            )
+        }
+        None => "All OAuth accounts are rate-limited. No reset time available.".to_string(),
+    };
+
+    Err(msg)
+}
+
+/// Swap to the next available OAuth account in the pool on rate-limit.
+///
+/// Identifies the currently active account (via `~/.claude/.credentials.json`),
+/// marks it as rate-limited, then refreshes and activates the next available
+/// account by writing its credentials to `~/.claude/.credentials.json`.
+///
+/// Returns the email of the newly activated account on success, or an error
+/// message when no account pool exists or all accounts are exhausted.
+pub async fn swap_to_next_available_account(
+    reset_at: chrono::DateTime<chrono::Utc>,
+) -> Result<String, String> {
+    slog!("[oauth] Rate limit hit — attempting account pool swap");
+
+    let mut pool = read_pool()?;
+
+    let reset_at_ms = reset_at.timestamp_millis() as u64;
+
+    let creds = read_credentials().unwrap_or_else(|_| CredentialsFile {
+        claude_ai_oauth: OAuthCredentials {
+            access_token: String::new(),
+            refresh_token: String::new(),
+            expires_at: 0,
+            scopes: vec![],
+            subscription_type: None,
+            rate_limit_tier: None,
+        },
+    });
+    let current_refresh_token = creds.claude_ai_oauth.refresh_token.clone();
+
+    let next_account =
+        select_next_account_for_swap(&mut pool, &current_refresh_token, reset_at_ms)?;
+
+    slog!(
+        "[oauth] Swapping to account '{}' — refreshing token",
+        next_account.email
+    );
+
+    // Refresh the next account's token via HTTP.
+    let (new_access_token, new_expires_at) = do_token_refresh(&next_account.refresh_token).await?;
+
+    // Update the pool account with the fresh token and clear rate-limited flag.
+    if let Some(pool_account) = pool.accounts.get_mut(&next_account.email) {
+        pool_account.access_token = new_access_token.clone();
+        pool_account.expires_at = new_expires_at;
+        pool_account.rate_limited = false;
+        pool_account.rate_limit_reset_at = None;
+    }
+
+    // Persist the updated pool (rate-limited flag on old account, fresh token on new).
+    write_pool(&pool)?;
+
+    // Write the new account's credentials to .credentials.json so the next
+    // Claude Code CLI invocation uses the freshly activated account.
+    let new_creds = CredentialsFile {
+        claude_ai_oauth: OAuthCredentials {
+            access_token: new_access_token,
+            refresh_token: next_account.refresh_token.clone(),
+            expires_at: new_expires_at,
+            scopes: next_account.scopes.clone(),
+            subscription_type: next_account.subscription_type.clone(),
+            rate_limit_tier: next_account.rate_limit_tier.clone(),
+        },
+    };
+    write_credentials(&new_creds)?;
+
+    slog!(
+        "[oauth] Account swap complete — now using '{}'",
+        next_account.email
+    );
+
+    Ok(next_account.email)
+}
+
 /// Extract the OAuth login URL from an error message produced by the Claude Code provider.
 ///
 /// The provider returns errors like:
@@ -331,4 +489,116 @@ mod tests {
             assert!(path.ends_with(".claude/.credentials.json"));
         }
     }
+
+    // ── select_next_account_for_swap ─────────────────────────────────────────
+
+    fn make_account(email: &str, refresh_token: &str, rate_limited: bool) -> PoolAccount {
+        PoolAccount {
+            email: email.to_string(),
+            access_token: format!("access-{email}"),
+            refresh_token: refresh_token.to_string(),
+            expires_at: 9_999_999_999_999,
+            scopes: vec![],
+            subscription_type: None,
+            rate_limit_tier: None,
+            rate_limited,
+            rate_limit_reset_at: None,
+        }
+    }
+
+    fn make_pool(accounts: Vec<PoolAccount>) -> AccountPool {
+        let mut pool = AccountPool::default();
+        for a in accounts {
+            pool.accounts.insert(a.email.clone(), a);
+        }
+        pool
+    }
+
+    /// AC3a: single rate-limit — current account is marked limited, swap to next.
+    #[test]
+    fn swap_selects_next_account_when_current_is_rate_limited() {
+        let account_a = make_account("a@example.com", "refresh-a", false);
+        let account_b = make_account("b@example.com", "refresh-b", false);
+        let mut pool = make_pool(vec![account_a, account_b]);
+
+        let reset_ms = 1_700_000_000_000u64;
+        let result = select_next_account_for_swap(&mut pool, "refresh-a", reset_ms);
+
+        assert!(result.is_ok(), "should find account B: {result:?}");
+        let next = result.unwrap();
+        assert_eq!(next.email, "b@example.com");
+
+        // Account A should now be marked rate-limited.
+        let a = pool.accounts.get("a@example.com").unwrap();
+        assert!(a.rate_limited, "account A should be marked rate-limited");
+        assert_eq!(a.rate_limit_reset_at, Some(reset_ms));
+    }
+
+    /// AC3b: cascade swap — next account is already rate-limited, picks the one after.
+    #[test]
+    fn swap_skips_already_rate_limited_account_and_picks_next_available() {
+        let account_a = make_account("a@example.com", "refresh-a", false);
+        let mut account_b = make_account("b@example.com", "refresh-b", false);
+        account_b.rate_limited = true; // B is already rate-limited
+        account_b.rate_limit_reset_at = Some(1_700_000_000_000);
+        let account_c = make_account("c@example.com", "refresh-c", false);
+
+        let mut pool = make_pool(vec![account_a, account_b, account_c]);
+
+        let reset_ms = 1_700_000_001_000u64;
+        let result = select_next_account_for_swap(&mut pool, "refresh-a", reset_ms);
+
+        assert!(result.is_ok(), "should find account C: {result:?}");
+        let next = result.unwrap();
+        assert_eq!(next.email, "c@example.com");
+    }
+
+    /// AC3c: all-exhausted error path — error message includes reset time.
+    #[test]
+    fn swap_returns_error_with_reset_time_when_all_accounts_exhausted() {
+        let account_a = make_account("a@example.com", "refresh-a", false);
+        let mut account_b = make_account("b@example.com", "refresh-b", false);
+        // B is already rate-limited with a known reset time.
+        account_b.rate_limited = true;
+        account_b.rate_limit_reset_at =
+            Some((chrono::Utc::now() + chrono::Duration::hours(2)).timestamp_millis() as u64);
+
+        let mut pool = make_pool(vec![account_a, account_b]);
+
+        // A also hits rate limit now → all exhausted.
+        let reset_ms = (chrono::Utc::now() + chrono::Duration::hours(1)).timestamp_millis() as u64;
+        let result = select_next_account_for_swap(&mut pool, "refresh-a", reset_ms);
+
+        assert!(result.is_err(), "should return exhausted error");
+        let msg = result.unwrap_err();
+        assert!(
+            msg.contains("All OAuth accounts are rate-limited"),
+            "error should say all exhausted: {msg}"
+        );
+        assert!(
+            msg.contains("minute"),
+            "error should include time until reset: {msg}"
+        );
+    }
+
+    /// Pool with fewer than 2 accounts returns no-pool error.
+    #[test]
+    fn swap_returns_error_when_pool_has_fewer_than_two_accounts() {
+        let mut pool = make_pool(vec![make_account("a@example.com", "refresh-a", false)]);
+        let result = select_next_account_for_swap(&mut pool, "refresh-a", 0);
+        assert!(result.is_err());
+        let msg = result.unwrap_err();
+        assert!(
+            msg.contains("fewer than 2 accounts"),
+            "should explain pool too small: {msg}"
+        );
+    }
+
+    /// Empty pool also returns no-pool error.
+    #[test]
+    fn swap_returns_error_for_empty_pool() {
+        let mut pool = AccountPool::default();
+        let result = select_next_account_for_swap(&mut pool, "any-token", 0);
+        assert!(result.is_err());
+    }
 }
diff --git a/server/src/service/oauth/io.rs b/server/src/service/oauth/io.rs
index 9e44b651..745083ab 100644
--- a/server/src/service/oauth/io.rs
+++ b/server/src/service/oauth/io.rs
@@ -126,6 +126,7 @@ pub(super) fn save_credentials(
         subscription_type: None,
         rate_limit_tier: None,
         rate_limited: false,
+        rate_limit_reset_at: None,
     };
     oauth::upsert_pool_account(account).map_err(Error::TokenStorage)?;
 
diff --git a/server/src/service/timer/io.rs b/server/src/service/timer/io.rs
index 7eed77ff..83b43cb2 100644
--- a/server/src/service/timer/io.rs
+++ b/server/src/service/timer/io.rs
@@ -331,6 +331,30 @@ pub fn spawn_rate_limit_auto_scheduler(
                         );
                         continue;
                     }
+
+                    // Try to swap to the next available OAuth account.  On
+                    // success the next agent start (via auto-assign) will use
+                    // the freshly activated account — no long timer needed.
+                    // On failure (no pool or all accounts exhausted) fall back
+                    // to the existing timer-based retry path.
+                    match crate::llm::oauth::swap_to_next_available_account(reset_at).await {
+                        Ok(new_email) => {
+                            crate::slog!(
+                                "[timer] Account swap successful for story {story_id} \
+                                 (agent {agent_name}): now using '{new_email}'. \
+                                 Auto-assign will restart the agent with the new account."
+                            );
+                            // No timer needed — auto-assign picks up the story.
+                            continue;
+                        }
+                        Err(swap_err) => {
+                            crate::slog!(
+                                "[timer] Account swap not possible for story {story_id}: \
+                                 {swap_err}. Falling back to timer-based retry."
+                            );
+                        }
+                    }
+
                     crate::slog!(
                         "[timer] Auto-scheduling timer for story {story_id} \
                          (agent {agent_name}) to resume at {reset_at}"