feat: expose pane zoom api

docs/next/CHANGELOG.md

@@ -11,6 +11,7 @@
 ### Added
 - Added `herdr integration install droid` for Factory Droid hooks that report session ids through Herdr's socket API. When native agent session restore is enabled, Herdr can resume Droid panes with `droid --resume <id>`.
 - Added directional pane swap with `prefix+shift+h/j/k/l`, a pane context-menu swap action, pane layout/neighbor/edge/focus/resize socket APIs, matching CLI commands, and optional `pane split --ratio` support.
+- Added `herdr pane zoom` and the `pane.zoom` socket API to toggle, set, or clear tab-local pane zoom from scripts and integrations.
 
 ## [0.6.8] - 2026-06-04
 

docs/next/README.md

@@ -162,7 +162,7 @@ not a gui window, not a web dashboard, not electron. herdr runs inside whatever
 
 ## agents can use herdr too
 
-The local Unix socket lets agents create workspaces, split panes, spawn helpers, read output, and wait for state changes. Start with the [socket API docs](https://herdr.dev/docs/socket-api/) and [`SKILL.md`](./SKILL.md).
+The local Unix socket lets agents create workspaces, split or zoom panes, spawn helpers, read output, and wait for state changes. Start with the [socket API docs](https://herdr.dev/docs/socket-api/) and [`SKILL.md`](./SKILL.md).
 
 ## supported agents
 

docs/next/website/src/content/docs/cli-reference.mdx

@@ -105,6 +105,7 @@ herdr pane neighbor --direction left|right|up|down [--pane ID|--current]
 herdr pane edges [--pane ID|--current]
 herdr pane focus --direction left|right|up|down [--pane ID|--current]
 herdr pane resize --direction left|right|up|down [--amount FLOAT] [--pane ID|--current]
+herdr pane zoom [<pane_id>|--pane ID|--current] [--toggle|--on|--off]
 herdr pane rename <pane_id> <label>|--clear
 herdr pane split [<pane_id>|--pane ID|--current] --direction right|down [--ratio FLOAT] [--cwd PATH] [--focus] [--no-focus]
 herdr pane swap --direction left|right|up|down [--pane ID|--current]

docs/next/website/src/content/docs/socket-api.mdx

@@ -58,6 +58,7 @@ herdr pane layout --current
 herdr pane neighbor --direction right --current
 herdr pane resize --direction right --amount 0.1 --current
 herdr pane swap --direction right --current
+herdr pane zoom --on --current
 herdr pane split 1-1 --direction right --ratio 0.333
 ```
 
@@ -83,7 +84,7 @@ Raw socket method names use dot notation:
 | Workspace | `workspace.create`, `workspace.list`, `workspace.get`, `workspace.focus`, `workspace.rename`, `workspace.close` |
 | Worktree | `worktree.list`, `worktree.create`, `worktree.open`, `worktree.remove` |
 | Tab | `tab.create`, `tab.list`, `tab.get`, `tab.focus`, `tab.rename`, `tab.close` |
-| Pane | `pane.split`, `pane.swap`, `pane.layout`, `pane.neighbor`, `pane.edges`, `pane.focus_direction`, `pane.resize`, `pane.list`, `pane.get`, `pane.rename`, `pane.send_text`, `pane.send_keys`, `pane.send_input`, `pane.read`, `pane.report_agent`, `pane.report_agent_session`, `pane.report_metadata`, `pane.clear_agent_authority`, `pane.release_agent`, `pane.close`, `pane.wait_for_output` |
+| Pane | `pane.split`, `pane.swap`, `pane.zoom`, `pane.layout`, `pane.neighbor`, `pane.edges`, `pane.focus_direction`, `pane.resize`, `pane.list`, `pane.get`, `pane.rename`, `pane.send_text`, `pane.send_keys`, `pane.send_input`, `pane.read`, `pane.report_agent`, `pane.report_agent_session`, `pane.report_metadata`, `pane.clear_agent_authority`, `pane.release_agent`, `pane.close`, `pane.wait_for_output` |
 | Agent | `agent.list`, `agent.get`, `agent.read`, `agent.send`, `agent.rename`, `agent.focus`, `agent.start` |
 | Events | `events.subscribe`, `events.wait` |
 | Integrations | `integration.install`, `integration.uninstall` |
@@ -99,6 +100,7 @@ the server's active focused pane.
 {"id":"req_edges","method":"pane.edges","params":{"pane_id":"1-1"}}
 {"id":"req_focus","method":"pane.focus_direction","params":{"direction":"right"}}
 {"id":"req_resize","method":"pane.resize","params":{"pane_id":"1-1","direction":"right","amount":0.1}}
+{"id":"req_zoom","method":"pane.zoom","params":{"pane_id":"1-1","mode":"toggle"}}
 {"id":"req_split","method":"pane.split","params":{"direction":"right","ratio":0.333}}
 ```
 
@@ -121,6 +123,20 @@ running processes. The response is `type: "pane_swap"` with `changed`, optional
 `cross_tab`. When a tab is zoomed, swap keeps zoom active and mutates the hidden
 full-tab layout.
 
+`pane.zoom` toggles, enables, or disables zoom for the target pane's tab:
+
+```json
+{"id":"req_zoom_toggle","method":"pane.zoom","params":{"pane_id":"1-1"}}
+{"id":"req_zoom_on","method":"pane.zoom","params":{"pane_id":"1-1","mode":"on"}}
+{"id":"req_zoom_off","method":"pane.zoom","params":{"pane_id":"1-1","mode":"off"}}
+```
+
+Omitting `pane_id` targets the server's active focused pane. The response is
+`type: "pane_zoom"` with `changed`, `zoom_changed`, `focus_changed`, optional
+`reason`, `pane_id`, `focused_pane_id`, `zoomed`, and `layout`. `changed` is
+true when either zoom state or focus changed. Reason values are `single_pane`,
+`already_zoomed`, and `already_unzoomed`.
+
 Worktree methods manage Git checkouts as Herdr workspaces. `worktree.create` creates a checkout and returns the new `workspace`, `tab`, `root_pane`, and `worktree` records. `worktree.open` opens an existing checkout or returns the already-open workspace. `worktree.remove` runs `git worktree remove` against a linked child workspace and never deletes the branch.
 
 Create a worktree from a source workspace:

src/api/mod.rs

@@ -38,6 +38,7 @@ pub(crate) fn request_changes_ui(request: &Request) -> bool {
             | Method::AgentStart(_)
             | Method::PaneSplit(_)
             | Method::PaneSwap(_)
+            | Method::PaneZoom(_)
             | Method::PaneFocusDirection(_)
             | Method::PaneResize(_)
             | Method::PaneRename(_)

src/api/schema.rs

@@ -2,6 +2,10 @@ use std::collections::HashMap;
 
 use serde::{Deserialize, Serialize};
 
+pub mod panes;
+
+pub use panes::*;
+
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct Request {
     pub id: String,
@@ -70,6 +74,8 @@ pub enum Method {
     PaneSplit(PaneSplitParams),
     #[serde(rename = "pane.swap")]
     PaneSwap(PaneSwapParams),
+    #[serde(rename = "pane.zoom")]
+    PaneZoom(PaneZoomParams),
     #[serde(rename = "pane.layout")]
     PaneLayout(PaneLayoutParams),
     #[serde(rename = "pane.neighbor")]
@@ -274,118 +280,6 @@ pub struct AgentStartParams {
     pub argv: Vec<String>,
 }
 
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-pub struct PaneSplitParams {
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub workspace_id: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub target_pane_id: Option<String>,
-    pub direction: SplitDirection,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub ratio: Option<f32>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub cwd: Option<String>,
-    #[serde(default)]
-    pub focus: bool,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(rename_all = "snake_case")]
-pub enum SplitDirection {
-    Right,
-    Down,
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(rename_all = "snake_case")]
-pub enum PaneDirection {
-    Left,
-    Right,
-    Up,
-    Down,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
-pub struct PaneSwapParams {
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub pane_id: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub direction: Option<PaneDirection>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub source_pane_id: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub target_pane_id: Option<String>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
-pub struct PaneLayoutParams {
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub pane_id: Option<String>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneNeighborParams {
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub pane_id: Option<String>,
-    pub direction: PaneDirection,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
-pub struct PaneEdgesParams {
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub pane_id: Option<String>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneFocusDirectionParams {
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub pane_id: Option<String>,
-    pub direction: PaneDirection,
-}
-
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-pub struct PaneResizeParams {
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub pane_id: Option<String>,
-    pub direction: PaneDirection,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub amount: Option<f32>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
-pub struct PaneListParams {
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub workspace_id: Option<String>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneRenameParams {
-    pub pane_id: String,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub label: Option<String>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneSendTextParams {
-    pub pane_id: String,
-    pub text: String,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneSendKeysParams {
-    pub pane_id: String,
-    pub keys: Vec<String>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneSendInputParams {
-    pub pane_id: String,
-    #[serde(default, skip_serializing_if = "String::is_empty")]
-    pub text: String,
-    #[serde(default, skip_serializing_if = "Vec::is_empty")]
-    pub keys: Vec<String>,
-}
-
 #[derive(Debug, Clone, Default, PartialEq, Eq, Serialize, Deserialize)]
 pub struct ServerLiveHandoffParams {
     #[serde(default, skip_serializing_if = "Option::is_none")]
@@ -396,97 +290,6 @@ pub struct ServerLiveHandoffParams {
     pub expected_version: Option<String>,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneReadParams {
-    pub pane_id: String,
-    pub source: ReadSource,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub lines: Option<u32>,
-    #[serde(default)]
-    pub format: ReadFormat,
-    #[serde(default = "default_true")]
-    pub strip_ansi: bool,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneReportAgentParams {
-    pub pane_id: String,
-    pub source: String,
-    pub agent: String,
-    pub state: PaneAgentState,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub message: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub custom_status: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub seq: Option<u64>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub agent_session_id: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub agent_session_path: Option<String>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneReportAgentSessionParams {
-    pub pane_id: String,
-    pub source: String,
-    pub agent: String,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub seq: Option<u64>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub agent_session_id: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub agent_session_path: Option<String>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneReportMetadataParams {
-    pub pane_id: String,
-    pub source: String,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub agent: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub applies_to_source: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub title: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub display_agent: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub custom_status: Option<String>,
-    #[serde(default, skip_serializing_if = "HashMap::is_empty")]
-    pub state_labels: HashMap<String, String>,
-    #[serde(default)]
-    pub clear_title: bool,
-    #[serde(default)]
-    pub clear_display_agent: bool,
-    #[serde(default)]
-    pub clear_custom_status: bool,
-    #[serde(default)]
-    pub clear_state_labels: bool,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub seq: Option<u64>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub ttl_ms: Option<u64>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneClearAgentAuthorityParams {
-    pub pane_id: String,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub source: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub seq: Option<u64>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneReleaseAgentParams {
-    pub pane_id: String,
-    pub source: String,
-    pub agent: String,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub seq: Option<u64>,
-}
-
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]
 pub enum ReadSource {
@@ -793,6 +596,9 @@ pub enum ResponseResult {
     PaneSwap {
         swap: PaneSwapResult,
     },
+    PaneZoom {
+        zoom: PaneZoomResult,
+    },
     PaneLayout {
         layout: PaneLayoutSnapshot,
     },
@@ -923,142 +729,6 @@ pub struct AgentInfo {
     pub revision: u64,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneInfo {
-    pub pane_id: String,
-    pub terminal_id: String,
-    pub workspace_id: String,
-    pub tab_id: String,
-    pub focused: bool,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub cwd: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub foreground_cwd: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub label: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub agent: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub title: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub display_agent: Option<String>,
-    pub agent_status: AgentStatus,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub custom_status: Option<String>,
-    #[serde(default, skip_serializing_if = "HashMap::is_empty")]
-    pub state_labels: HashMap<String, String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub agent_session: Option<AgentSessionInfo>,
-    pub revision: u64,
-}
-
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-pub struct PaneSwapResult {
-    pub changed: bool,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub reason: Option<PaneSwapReason>,
-    pub source_pane_id: String,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub target_pane_id: Option<String>,
-    pub focused_pane_id: String,
-    pub layout: PaneLayoutSnapshot,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(rename_all = "snake_case")]
-pub enum PaneSwapReason {
-    NoNeighbor,
-    SamePane,
-    NotFound,
-    CrossTab,
-}
-
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-pub struct PaneLayoutSnapshot {
-    pub workspace_id: String,
-    pub tab_id: String,
-    pub zoomed: bool,
-    pub area: PaneLayoutRect,
-    pub focused_pane_id: String,
-    pub panes: Vec<PaneLayoutPane>,
-    pub splits: Vec<PaneLayoutSplit>,
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneLayoutRect {
-    pub x: u16,
-    pub y: u16,
-    pub width: u16,
-    pub height: u16,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneLayoutPane {
-    pub pane_id: String,
-    pub focused: bool,
-    pub rect: PaneLayoutRect,
-}
-
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-pub struct PaneLayoutSplit {
-    pub id: String,
-    pub direction: SplitDirection,
-    pub ratio: f32,
-    pub rect: PaneLayoutRect,
-}
-
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-pub struct PaneNeighborResult {
-    pub pane_id: String,
-    pub direction: PaneDirection,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub neighbor_pane_id: Option<String>,
-    pub layout: PaneLayoutSnapshot,
-}
-
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-pub struct PaneEdgesResult {
-    pub pane_id: String,
-    pub left: bool,
-    pub right: bool,
-    pub up: bool,
-    pub down: bool,
-    pub layout: PaneLayoutSnapshot,
-}
-
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-pub struct PaneFocusDirectionResult {
-    pub changed: bool,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub reason: Option<PaneFocusDirectionReason>,
-    pub source_pane_id: String,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub focused_pane_id: Option<String>,
-    pub layout: PaneLayoutSnapshot,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(rename_all = "snake_case")]
-pub enum PaneFocusDirectionReason {
-    NoNeighbor,
-}
-
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
-pub struct PaneResizeResult {
-    pub changed: bool,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub reason: Option<PaneResizeReason>,
-    pub pane_id: String,
-    pub focused_pane_id: String,
-    pub layout: PaneLayoutSnapshot,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-#[serde(rename_all = "snake_case")]
-pub enum PaneResizeReason {
-    Unchanged,
-}
-
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct AgentSessionInfo {
     pub source: String,
@@ -1067,18 +737,6 @@ pub struct AgentSessionInfo {
     pub value: String,
 }
 
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
-pub struct PaneReadResult {
-    pub pane_id: String,
-    pub workspace_id: String,
-    pub tab_id: String,
-    pub source: ReadSource,
-    pub format: ReadFormat,
-    pub text: String,
-    pub revision: u64,
-    pub truncated: bool,
-}
-
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct IntegrationInstallResult {
     pub messages: Vec<String>,

src/api/schema/panes.rs

@@ -0,0 +1,394 @@
+use std::collections::HashMap;
+
+use serde::{Deserialize, Serialize};
+
+use super::{AgentSessionInfo, AgentStatus, PaneAgentState, ReadFormat, ReadSource};
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct PaneSplitParams {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub workspace_id: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub target_pane_id: Option<String>,
+    pub direction: SplitDirection,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub ratio: Option<f32>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub cwd: Option<String>,
+    #[serde(default)]
+    pub focus: bool,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum SplitDirection {
+    Right,
+    Down,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum PaneDirection {
+    Left,
+    Right,
+    Up,
+    Down,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub struct PaneSwapParams {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub pane_id: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub direction: Option<PaneDirection>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub source_pane_id: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub target_pane_id: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub struct PaneZoomParams {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub pane_id: Option<String>,
+    #[serde(default)]
+    pub mode: PaneZoomMode,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize, Default)]
+#[serde(rename_all = "snake_case")]
+pub enum PaneZoomMode {
+    #[default]
+    Toggle,
+    On,
+    Off,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub struct PaneLayoutParams {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub pane_id: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneNeighborParams {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub pane_id: Option<String>,
+    pub direction: PaneDirection,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub struct PaneEdgesParams {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub pane_id: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneFocusDirectionParams {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub pane_id: Option<String>,
+    pub direction: PaneDirection,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct PaneResizeParams {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub pane_id: Option<String>,
+    pub direction: PaneDirection,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub amount: Option<f32>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
+pub struct PaneListParams {
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub workspace_id: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneRenameParams {
+    pub pane_id: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub label: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneSendTextParams {
+    pub pane_id: String,
+    pub text: String,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneSendKeysParams {
+    pub pane_id: String,
+    pub keys: Vec<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneSendInputParams {
+    pub pane_id: String,
+    #[serde(default, skip_serializing_if = "String::is_empty")]
+    pub text: String,
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub keys: Vec<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneReadParams {
+    pub pane_id: String,
+    pub source: ReadSource,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub lines: Option<u32>,
+    #[serde(default)]
+    pub format: ReadFormat,
+    #[serde(default = "super::default_true")]
+    pub strip_ansi: bool,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneReportAgentParams {
+    pub pane_id: String,
+    pub source: String,
+    pub agent: String,
+    pub state: PaneAgentState,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub message: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub custom_status: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub seq: Option<u64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub agent_session_id: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub agent_session_path: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneReportAgentSessionParams {
+    pub pane_id: String,
+    pub source: String,
+    pub agent: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub seq: Option<u64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub agent_session_id: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub agent_session_path: Option<String>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneReportMetadataParams {
+    pub pane_id: String,
+    pub source: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub agent: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub applies_to_source: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub display_agent: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub custom_status: Option<String>,
+    #[serde(default, skip_serializing_if = "HashMap::is_empty")]
+    pub state_labels: HashMap<String, String>,
+    #[serde(default)]
+    pub clear_title: bool,
+    #[serde(default)]
+    pub clear_display_agent: bool,
+    #[serde(default)]
+    pub clear_custom_status: bool,
+    #[serde(default)]
+    pub clear_state_labels: bool,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub seq: Option<u64>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub ttl_ms: Option<u64>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneClearAgentAuthorityParams {
+    pub pane_id: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub source: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub seq: Option<u64>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneReleaseAgentParams {
+    pub pane_id: String,
+    pub source: String,
+    pub agent: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub seq: Option<u64>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneInfo {
+    pub pane_id: String,
+    pub terminal_id: String,
+    pub workspace_id: String,
+    pub tab_id: String,
+    pub focused: bool,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub cwd: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub foreground_cwd: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub label: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub agent: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub title: Option<String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub display_agent: Option<String>,
+    pub agent_status: AgentStatus,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub custom_status: Option<String>,
+    #[serde(default, skip_serializing_if = "HashMap::is_empty")]
+    pub state_labels: HashMap<String, String>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub agent_session: Option<AgentSessionInfo>,
+    pub revision: u64,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct PaneSwapResult {
+    pub changed: bool,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub reason: Option<PaneSwapReason>,
+    pub source_pane_id: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub target_pane_id: Option<String>,
+    pub focused_pane_id: String,
+    pub layout: PaneLayoutSnapshot,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum PaneSwapReason {
+    NoNeighbor,
+    SamePane,
+    NotFound,
+    CrossTab,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct PaneZoomResult {
+    pub changed: bool,
+    pub zoom_changed: bool,
+    pub focus_changed: bool,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub reason: Option<PaneZoomReason>,
+    pub pane_id: String,
+    pub focused_pane_id: String,
+    pub zoomed: bool,
+    pub layout: PaneLayoutSnapshot,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum PaneZoomReason {
+    SinglePane,
+    AlreadyZoomed,
+    AlreadyUnzoomed,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct PaneLayoutSnapshot {
+    pub workspace_id: String,
+    pub tab_id: String,
+    pub zoomed: bool,
+    pub area: PaneLayoutRect,
+    pub focused_pane_id: String,
+    pub panes: Vec<PaneLayoutPane>,
+    pub splits: Vec<PaneLayoutSplit>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneLayoutRect {
+    pub x: u16,
+    pub y: u16,
+    pub width: u16,
+    pub height: u16,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneLayoutPane {
+    pub pane_id: String,
+    pub focused: bool,
+    pub rect: PaneLayoutRect,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct PaneLayoutSplit {
+    pub id: String,
+    pub direction: SplitDirection,
+    pub ratio: f32,
+    pub rect: PaneLayoutRect,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct PaneNeighborResult {
+    pub pane_id: String,
+    pub direction: PaneDirection,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub neighbor_pane_id: Option<String>,
+    pub layout: PaneLayoutSnapshot,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct PaneEdgesResult {
+    pub pane_id: String,
+    pub left: bool,
+    pub right: bool,
+    pub up: bool,
+    pub down: bool,
+    pub layout: PaneLayoutSnapshot,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct PaneFocusDirectionResult {
+    pub changed: bool,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub reason: Option<PaneFocusDirectionReason>,
+    pub source_pane_id: String,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub focused_pane_id: Option<String>,
+    pub layout: PaneLayoutSnapshot,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum PaneFocusDirectionReason {
+    NoNeighbor,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct PaneResizeResult {
+    pub changed: bool,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub reason: Option<PaneResizeReason>,
+    pub pane_id: String,
+    pub focused_pane_id: String,
+    pub layout: PaneLayoutSnapshot,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum PaneResizeReason {
+    Unchanged,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PaneReadResult {
+    pub pane_id: String,
+    pub workspace_id: String,
+    pub tab_id: String,
+    pub source: ReadSource,
+    pub format: ReadFormat,
+    pub text: String,
+    pub revision: u64,
+    pub truncated: bool,
+}

src/api/server.rs

@@ -296,6 +296,7 @@ fn api_method_name(method: &Method) -> &'static str {
         Method::AgentStart(_) => "agent.start",
         Method::PaneSplit(_) => "pane.split",
         Method::PaneSwap(_) => "pane.swap",
+        Method::PaneZoom(_) => "pane.zoom",
         Method::PaneLayout(_) => "pane.layout",
         Method::PaneNeighbor(_) => "pane.neighbor",
         Method::PaneEdges(_) => "pane.edges",

src/app/actions.rs

@@ -1350,6 +1350,28 @@ impl AppState {
 // Pane operations
 // ---------------------------------------------------------------------------
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum PaneZoomCommand {
+    Toggle,
+    On,
+    Off,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum PaneZoomNoopReason {
+    SinglePane,
+    AlreadyZoomed,
+    AlreadyUnzoomed,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) struct PaneZoomOutcome {
+    pub changed: bool,
+    pub focus_changed: bool,
+    pub reason: Option<PaneZoomNoopReason>,
+    pub zoomed: bool,
+}
+
 impl AppState {
     pub fn navigate_pane(&mut self, direction: NavDirection) {
         let Some(ws_idx) = self.active else {
@@ -1468,17 +1490,72 @@ impl AppState {
         }
     }
 
-    pub fn toggle_zoom(&mut self) {
-        if let Some(tab) = self
-            .active
-            .and_then(|i| self.workspaces.get_mut(i))
-            .and_then(|ws| ws.active_tab_mut())
-        {
-            if tab.layout.pane_count() > 1 {
-                tab.zoomed = !tab.zoomed;
-                self.mark_session_dirty();
-            }
+    pub(crate) fn apply_pane_zoom(
+        &mut self,
+        ws_idx: usize,
+        pane_id: PaneId,
+        command: PaneZoomCommand,
+    ) -> Option<PaneZoomOutcome> {
+        let tab_idx = self
+            .workspaces
+            .get(ws_idx)?
+            .find_tab_index_for_pane(pane_id)?;
+        let focus_changed = self.focus_pane_in_workspace(ws_idx, pane_id);
+        let tab = self
+            .workspaces
+            .get_mut(ws_idx)
+            .and_then(|ws| ws.tabs.get_mut(tab_idx))?;
+        if tab.layout.pane_count() <= 1 {
+            return Some(PaneZoomOutcome {
+                changed: false,
+                focus_changed,
+                reason: Some(PaneZoomNoopReason::SinglePane),
+                zoomed: tab.zoomed,
+            });
         }
+
+        let desired = match command {
+            PaneZoomCommand::Toggle => !tab.zoomed,
+            PaneZoomCommand::On => true,
+            PaneZoomCommand::Off => false,
+        };
+        let reason = match (command, tab.zoomed) {
+            (PaneZoomCommand::On, true) => Some(PaneZoomNoopReason::AlreadyZoomed),
+            (PaneZoomCommand::Off, false) => Some(PaneZoomNoopReason::AlreadyUnzoomed),
+            _ => None,
+        };
+        if reason.is_some() {
+            return Some(PaneZoomOutcome {
+                changed: false,
+                focus_changed,
+                reason,
+                zoomed: tab.zoomed,
+            });
+        }
+
+        tab.zoomed = desired;
+        let zoomed = tab.zoomed;
+        self.mark_session_dirty();
+        Some(PaneZoomOutcome {
+            changed: true,
+            focus_changed,
+            reason: None,
+            zoomed,
+        })
+    }
+
+    pub fn toggle_zoom(&mut self) {
+        let Some(ws_idx) = self.active else {
+            return;
+        };
+        let Some(pane_id) = self
+            .workspaces
+            .get(ws_idx)
+            .and_then(crate::workspace::Workspace::focused_pane_id)
+        else {
+            return;
+        };
+        self.apply_pane_zoom(ws_idx, pane_id, PaneZoomCommand::Toggle);
     }
 
     pub(crate) fn workspace_close_would_close_worktree_group(&self, ws_idx: usize) -> bool {

src/app/api.rs

@@ -556,6 +556,7 @@ impl App {
             Method::AgentSend(params) => return self.handle_agent_send(request.id, params),
             Method::PaneSplit(params) => return self.handle_pane_split(request.id, params),
             Method::PaneSwap(params) => return self.handle_pane_swap(request.id, params),
+            Method::PaneZoom(params) => return self.handle_pane_zoom(request.id, params),
             Method::PaneLayout(params) => return self.handle_pane_layout(request.id, params),
             Method::PaneNeighbor(params) => return self.handle_pane_neighbor(request.id, params),
             Method::PaneEdges(params) => return self.handle_pane_edges(request.id, params),

src/app/api/panes.rs

@@ -8,9 +8,10 @@ use crate::api::schema::{
     PaneReadResult, PaneReleaseAgentParams, PaneRenameParams, PaneReportAgentParams,
     PaneReportAgentSessionParams, PaneReportMetadataParams, PaneResizeParams, PaneResizeReason,
     PaneResizeResult, PaneSendInputParams, PaneSendKeysParams, PaneSendTextParams, PaneSplitParams,
-    PaneSwapParams, PaneSwapReason, PaneSwapResult, PaneTarget, ReadFormat, ReadSource,
-    ResponseResult,
+    PaneSwapParams, PaneSwapReason, PaneSwapResult, PaneTarget, PaneZoomMode, PaneZoomParams,
+    PaneZoomReason, PaneZoomResult, ReadFormat, ReadSource, ResponseResult,
 };
+use crate::app::actions::{PaneZoomCommand, PaneZoomNoopReason};
 use crate::app::{App, Mode};
 use crate::layout::{find_in_direction, NavDirection, PaneId};
 
@@ -517,6 +518,57 @@ impl App {
         )
     }
 
+    pub(super) fn handle_pane_zoom(&mut self, id: String, params: PaneZoomParams) -> String {
+        let Some((ws_idx, pane_id)) = self.resolve_optional_pane(params.pane_id.as_deref()) else {
+            return encode_error(id, "pane_not_found", "pane not found");
+        };
+        let Some(tab_idx) = self.state.workspaces[ws_idx].find_tab_index_for_pane(pane_id) else {
+            return pane_not_found(
+                id,
+                &self.public_pane_id(ws_idx, pane_id).unwrap_or_default(),
+            );
+        };
+        let Some(pane_public_id) = self.public_pane_id(ws_idx, pane_id) else {
+            return encode_error(id, "pane_not_found", "pane not found");
+        };
+        let command = match params.mode {
+            PaneZoomMode::Toggle => PaneZoomCommand::Toggle,
+            PaneZoomMode::On => PaneZoomCommand::On,
+            PaneZoomMode::Off => PaneZoomCommand::Off,
+        };
+        let Some(outcome) = self.state.apply_pane_zoom(ws_idx, pane_id, command) else {
+            return pane_not_found(id, &pane_public_id);
+        };
+        if outcome.changed || outcome.focus_changed {
+            self.schedule_session_save();
+        }
+        self.state.mode = Mode::Terminal;
+        let Some(layout) = self.pane_layout_snapshot(ws_idx, tab_idx) else {
+            return encode_error(id, "pane_layout_unavailable", "pane layout unavailable");
+        };
+        let focused_pane_id = layout.focused_pane_id.clone();
+
+        encode_success(
+            id,
+            ResponseResult::PaneZoom {
+                zoom: PaneZoomResult {
+                    changed: outcome.changed || outcome.focus_changed,
+                    zoom_changed: outcome.changed,
+                    focus_changed: outcome.focus_changed,
+                    reason: outcome.reason.map(|reason| match reason {
+                        PaneZoomNoopReason::SinglePane => PaneZoomReason::SinglePane,
+                        PaneZoomNoopReason::AlreadyZoomed => PaneZoomReason::AlreadyZoomed,
+                        PaneZoomNoopReason::AlreadyUnzoomed => PaneZoomReason::AlreadyUnzoomed,
+                    }),
+                    pane_id: pane_public_id,
+                    focused_pane_id,
+                    zoomed: outcome.zoomed,
+                    layout,
+                },
+            },
+        )
+    }
+
     pub(super) fn handle_pane_rename(&mut self, id: String, params: PaneRenameParams) -> String {
         let Some((ws_idx, pane_id)) = self.parse_pane_id(&params.pane_id) else {
             return pane_not_found(id, &params.pane_id);
@@ -1280,6 +1332,240 @@ mod tests {
         assert_eq!(swap.layout.workspace_id, app.public_workspace_id(0));
     }
 
+    #[test]
+    fn api_pane_zoom_current_toggles_zoom() {
+        let mut app = app_with_linked_worktree();
+        app.state.active = Some(0);
+        app.state.selected = 0;
+        let root = app.state.workspaces[0].tabs[0].root_pane;
+        let _right = app.state.workspaces[0].test_split(ratatui::layout::Direction::Horizontal);
+        app.state.workspaces[0].tabs[0].layout.focus_pane(root);
+        let root_public = app.public_pane_id(0, root).unwrap();
+
+        let response = app.handle_pane_zoom("req".into(), PaneZoomParams::default());
+
+        let success: SuccessResponse = serde_json::from_str(&response).unwrap();
+        let ResponseResult::PaneZoom { zoom } = success.result else {
+            panic!("expected pane zoom response");
+        };
+        assert!(zoom.changed);
+        assert!(zoom.zoom_changed);
+        assert!(!zoom.focus_changed);
+        assert_eq!(zoom.reason, None);
+        assert_eq!(zoom.pane_id, root_public);
+        assert_eq!(zoom.focused_pane_id, zoom.pane_id);
+        assert!(zoom.zoomed);
+        assert!(zoom.layout.zoomed);
+
+        let response = app.handle_pane_zoom("req".into(), PaneZoomParams::default());
+        let success: SuccessResponse = serde_json::from_str(&response).unwrap();
+        let ResponseResult::PaneZoom { zoom } = success.result else {
+            panic!("expected pane zoom response");
+        };
+        assert!(zoom.changed);
+        assert!(zoom.zoom_changed);
+        assert!(!zoom.focus_changed);
+        assert!(!zoom.zoomed);
+        assert!(!zoom.layout.zoomed);
+    }
+
+    #[test]
+    fn api_pane_zoom_explicit_background_pane_updates_focus_history() {
+        let mut app = app_with_linked_worktree();
+        app.state.workspaces.push(Workspace::test_new("other"));
+        let first = app.state.workspaces[0].tabs[0].root_pane;
+        let target = app.state.workspaces[1].tabs[0].root_pane;
+        let _other = app.state.workspaces[1].test_split(ratatui::layout::Direction::Horizontal);
+        app.state.active = Some(0);
+        app.state.selected = 0;
+        app.state.workspaces[0].tabs[0].layout.focus_pane(first);
+        let target_public = app.public_pane_id(1, target).unwrap();
+
+        let response = app.handle_pane_zoom(
+            "req".into(),
+            PaneZoomParams {
+                pane_id: Some(target_public.clone()),
+                mode: PaneZoomMode::On,
+            },
+        );
+
+        let success: SuccessResponse = serde_json::from_str(&response).unwrap();
+        let ResponseResult::PaneZoom { zoom } = success.result else {
+            panic!("expected pane zoom response");
+        };
+        assert!(zoom.changed);
+        assert!(zoom.zoom_changed);
+        assert!(zoom.focus_changed);
+        assert_eq!(zoom.pane_id, target_public);
+        assert_eq!(app.state.active, Some(1));
+        assert_eq!(app.state.workspaces[1].focused_pane_id(), Some(target));
+        assert!(app.state.workspaces[1].tabs[0].zoomed);
+
+        app.state.last_pane();
+
+        assert_eq!(app.state.active, Some(0));
+        assert_eq!(app.state.workspaces[0].focused_pane_id(), Some(first));
+    }
+
+    #[test]
+    fn api_pane_zoom_single_pane_returns_noop() {
+        let mut app = app_with_linked_worktree();
+        app.state.active = Some(0);
+        app.state.selected = 0;
+        let root = app.state.workspaces[0].tabs[0].root_pane;
+        let root_public = app.public_pane_id(0, root).unwrap();
+
+        let response = app.handle_pane_zoom(
+            "req".into(),
+            PaneZoomParams {
+                pane_id: Some(root_public.clone()),
+                mode: PaneZoomMode::Toggle,
+            },
+        );
+
+        let success: SuccessResponse = serde_json::from_str(&response).unwrap();
+        let ResponseResult::PaneZoom { zoom } = success.result else {
+            panic!("expected pane zoom response");
+        };
+        assert!(!zoom.changed);
+        assert!(!zoom.zoom_changed);
+        assert!(!zoom.focus_changed);
+        assert_eq!(zoom.reason, Some(PaneZoomReason::SinglePane));
+        assert_eq!(zoom.pane_id, root_public);
+        assert!(!zoom.zoomed);
+        assert!(!app.state.workspaces[0].tabs[0].zoomed);
+    }
+
+    #[test]
+    fn api_pane_zoom_on_and_off_are_idempotent() {
+        let mut app = app_with_linked_worktree();
+        app.state.active = Some(0);
+        app.state.selected = 0;
+        let root = app.state.workspaces[0].tabs[0].root_pane;
+        let _right = app.state.workspaces[0].test_split(ratatui::layout::Direction::Horizontal);
+        app.state.workspaces[0].tabs[0].layout.focus_pane(root);
+        let root_public = app.public_pane_id(0, root).unwrap();
+
+        let response = app.handle_pane_zoom(
+            "req".into(),
+            PaneZoomParams {
+                pane_id: Some(root_public.clone()),
+                mode: PaneZoomMode::On,
+            },
+        );
+        let success: SuccessResponse = serde_json::from_str(&response).unwrap();
+        let ResponseResult::PaneZoom { zoom } = success.result else {
+            panic!("expected pane zoom response");
+        };
+        assert!(zoom.changed);
+        assert!(zoom.zoom_changed);
+        assert!(!zoom.focus_changed);
+        assert!(zoom.zoomed);
+
+        let response = app.handle_pane_zoom(
+            "req".into(),
+            PaneZoomParams {
+                pane_id: Some(root_public.clone()),
+                mode: PaneZoomMode::On,
+            },
+        );
+        let success: SuccessResponse = serde_json::from_str(&response).unwrap();
+        let ResponseResult::PaneZoom { zoom } = success.result else {
+            panic!("expected pane zoom response");
+        };
+        assert!(!zoom.changed);
+        assert!(!zoom.zoom_changed);
+        assert!(!zoom.focus_changed);
+        assert_eq!(zoom.reason, Some(PaneZoomReason::AlreadyZoomed));
+        assert!(zoom.zoomed);
+
+        let response = app.handle_pane_zoom(
+            "req".into(),
+            PaneZoomParams {
+                pane_id: Some(root_public),
+                mode: PaneZoomMode::Off,
+            },
+        );
+        let success: SuccessResponse = serde_json::from_str(&response).unwrap();
+        let ResponseResult::PaneZoom { zoom } = success.result else {
+            panic!("expected pane zoom response");
+        };
+        assert!(zoom.changed);
+        assert!(zoom.zoom_changed);
+        assert!(!zoom.focus_changed);
+        assert!(!zoom.zoomed);
+
+        let response = app.handle_pane_zoom(
+            "req".into(),
+            PaneZoomParams {
+                pane_id: None,
+                mode: PaneZoomMode::Off,
+            },
+        );
+        let success: SuccessResponse = serde_json::from_str(&response).unwrap();
+        let ResponseResult::PaneZoom { zoom } = success.result else {
+            panic!("expected pane zoom response");
+        };
+        assert!(!zoom.changed);
+        assert!(!zoom.zoom_changed);
+        assert!(!zoom.focus_changed);
+        assert_eq!(zoom.reason, Some(PaneZoomReason::AlreadyUnzoomed));
+        assert!(!zoom.zoomed);
+    }
+
+    #[test]
+    fn api_pane_zoom_idempotent_mode_reports_focus_change() {
+        let mut app = app_with_linked_worktree();
+        app.state.active = Some(0);
+        app.state.selected = 0;
+        let root = app.state.workspaces[0].tabs[0].root_pane;
+        let right = app.state.workspaces[0].test_split(ratatui::layout::Direction::Horizontal);
+        app.state.workspaces[0].tabs[0].layout.focus_pane(root);
+        app.state.workspaces[0].tabs[0].zoomed = true;
+        let right_public = app.public_pane_id(0, right).unwrap();
+
+        let response = app.handle_pane_zoom(
+            "req".into(),
+            PaneZoomParams {
+                pane_id: Some(right_public),
+                mode: PaneZoomMode::On,
+            },
+        );
+
+        let success: SuccessResponse = serde_json::from_str(&response).unwrap();
+        let ResponseResult::PaneZoom { zoom } = success.result else {
+            panic!("expected pane zoom response");
+        };
+        assert!(zoom.changed);
+        assert!(!zoom.zoom_changed);
+        assert!(zoom.focus_changed);
+        assert_eq!(zoom.reason, Some(PaneZoomReason::AlreadyZoomed));
+        assert!(zoom.zoomed);
+        assert_eq!(app.state.workspaces[0].focused_pane_id(), Some(right));
+    }
+
+    #[test]
+    fn api_pane_zoom_params_serialize_modes() {
+        let request = crate::api::schema::Request {
+            id: "req".into(),
+            method: crate::api::schema::Method::PaneZoom(PaneZoomParams {
+                pane_id: Some("issue-1".into()),
+                mode: PaneZoomMode::On,
+            }),
+        };
+
+        let encoded = serde_json::to_string(&request).unwrap();
+        assert!(encoded.contains("\"method\":\"pane.zoom\""));
+        assert!(encoded.contains("\"mode\":\"on\""));
+
+        let decoded: crate::api::schema::Request = serde_json::from_str(&encoded).unwrap();
+        let crate::api::schema::Method::PaneZoom(params) = decoded.method else {
+            panic!("expected pane zoom request");
+        };
+        assert_eq!(params.pane_id, Some("issue-1".into()));
+        assert_eq!(params.mode, PaneZoomMode::On);
+    }
+
     #[test]
     fn api_pane_layout_returns_public_ids_rects_and_splits() {
         let mut app = app_with_linked_worktree();

src/cli/pane.rs

@@ -2,8 +2,8 @@ use crate::api::schema::{
     Method, PaneDirection, PaneEdgesParams, PaneFocusDirectionParams, PaneLayoutParams,
     PaneListParams, PaneNeighborParams, PaneReadParams, PaneRenameParams, PaneReportAgentParams,
     PaneReportMetadataParams, PaneResizeParams, PaneSendInputParams, PaneSendKeysParams,
-    PaneSendTextParams, PaneSplitParams, PaneSwapParams, PaneTarget, ReadFormat, ReadSource,
-    Request,
+    PaneSendTextParams, PaneSplitParams, PaneSwapParams, PaneTarget, PaneZoomMode, PaneZoomParams,
+    ReadFormat, ReadSource, Request,
 };
 
 pub(super) fn run_pane_command(args: &[String]) -> std::io::Result<i32> {
@@ -20,6 +20,7 @@ pub(super) fn run_pane_command(args: &[String]) -> std::io::Result<i32> {
         "edges" => pane_edges(&args[1..]),
         "focus" => pane_focus(&args[1..]),
         "resize" => pane_resize(&args[1..]),
+        "zoom" => pane_zoom(&args[1..]),
         "read" => pane_read(&args[1..]),
         "rename" => pane_rename(&args[1..]),
         "split" => pane_split(&args[1..]),
@@ -289,6 +290,78 @@ fn parse_pane_resize_args(args: &[String]) -> Result<PaneResizeParams, String> {
     })
 }
 
+fn pane_zoom(args: &[String]) -> std::io::Result<i32> {
+    let params = match parse_pane_zoom_args(args) {
+        Ok(params) => params,
+        Err(message) => {
+            eprintln!("{message}");
+            return Ok(2);
+        }
+    };
+
+    super::print_response(&super::send_request(&Request {
+        id: "cli:pane:zoom".into(),
+        method: Method::PaneZoom(params),
+    })?)
+}
+
+fn parse_pane_zoom_args(args: &[String]) -> Result<PaneZoomParams, String> {
+    let mut pane_id = None;
+    let mut mode = PaneZoomMode::Toggle;
+    let mut mode_seen = false;
+
+    let mut index = 0;
+    if args
+        .first()
+        .is_some_and(|arg| !arg.as_str().starts_with("--"))
+    {
+        pane_id = args.first().map(|arg| super::normalize_pane_id(arg));
+        index = 1;
+    }
+    while index < args.len() {
+        match args[index].as_str() {
+            "--pane" => {
+                let Some(value) = args.get(index + 1) else {
+                    return Err("missing value for --pane".into());
+                };
+                pane_id = Some(super::normalize_pane_id(value));
+                index += 2;
+            }
+            "--current" => {
+                pane_id = None;
+                index += 1;
+            }
+            "--toggle" => {
+                if mode_seen {
+                    return Err("provide only one of --toggle, --on, or --off".into());
+                }
+                mode = PaneZoomMode::Toggle;
+                mode_seen = true;
+                index += 1;
+            }
+            "--on" => {
+                if mode_seen {
+                    return Err("provide only one of --toggle, --on, or --off".into());
+                }
+                mode = PaneZoomMode::On;
+                mode_seen = true;
+                index += 1;
+            }
+            "--off" => {
+                if mode_seen {
+                    return Err("provide only one of --toggle, --on, or --off".into());
+                }
+                mode = PaneZoomMode::Off;
+                mode_seen = true;
+                index += 1;
+            }
+            other => return Err(format!("unknown option: {other}")),
+        }
+    }
+
+    Ok(PaneZoomParams { pane_id, mode })
+}
+
 fn pane_rename(args: &[String]) -> std::io::Result<i32> {
     let Some(raw_pane_id) = args.first() else {
         eprintln!("usage: herdr pane rename <pane_id> <label>|--clear");
@@ -953,6 +1026,7 @@ fn print_pane_help() {
     eprintln!(
         "  herdr pane resize --direction left|right|up|down [--amount FLOAT] [--pane ID|--current]"
     );
+    eprintln!("  herdr pane zoom [<pane_id>|--pane ID|--current] [--toggle|--on|--off]");
     eprintln!("  herdr pane rename <pane_id> <label>|--clear");
     eprintln!("  herdr pane read <pane_id> [--source visible|recent|recent-unwrapped] [--lines N] [--format text|ansi] [--ansi]");
     eprintln!(
@@ -1049,6 +1123,37 @@ mod tests {
         assert!(err.contains("usage: herdr pane swap"));
     }
 
+    #[test]
+    fn parse_pane_zoom_args_defaults_to_current_toggle() {
+        let params = parse_pane_zoom_args(&args(&[])).unwrap();
+
+        assert_eq!(params.pane_id, None);
+        assert_eq!(params.mode, PaneZoomMode::Toggle);
+    }
+
+    #[test]
+    fn parse_pane_zoom_args_accepts_positional_pane_and_on() {
+        let params = parse_pane_zoom_args(&args(&["issue-1", "--on"])).unwrap();
+
+        assert_eq!(params.pane_id, Some("issue-1".into()));
+        assert_eq!(params.mode, PaneZoomMode::On);
+    }
+
+    #[test]
+    fn parse_pane_zoom_args_accepts_pane_option_and_off() {
+        let params = parse_pane_zoom_args(&args(&["--pane", "issue-2", "--off"])).unwrap();
+
+        assert_eq!(params.pane_id, Some("issue-2".into()));
+        assert_eq!(params.mode, PaneZoomMode::Off);
+    }
+
+    #[test]
+    fn parse_pane_zoom_args_rejects_multiple_modes() {
+        let err = parse_pane_zoom_args(&args(&["--on", "--off"])).unwrap_err();
+
+        assert!(err.contains("provide only one"));
+    }
+
     #[test]
     fn parse_pane_neighbor_args_accepts_directional_current() {
         let params = parse_pane_neighbor_args(&args(&["--direction", "down"])).unwrap();