diff --git a/src/client/src/appState.ts b/src/client/src/appState.ts
index 409bf73..17776d7 100644
--- a/src/client/src/appState.ts
+++ b/src/client/src/appState.ts
@@ -45,6 +45,7 @@ export interface AppState {
   activeTerminalCount: number;
   selectedTerminalId: string | undefined;
   piWebStatus: PiWebStatusResponse | undefined;
+  workspacePanelCollapsed: boolean;
   error: string;
 }
 
@@ -133,6 +134,7 @@ export function initialAppState(): AppState {
     activeTerminalCount: 0,
     selectedTerminalId: undefined,
     piWebStatus: undefined,
+    workspacePanelCollapsed: false,
     error: "",
   };
 }
diff --git a/src/client/src/components/PiWebApp.ts b/src/client/src/components/PiWebApp.ts
index 564f86c..fd4a1fa 100644
--- a/src/client/src/components/PiWebApp.ts
+++ b/src/client/src/components/PiWebApp.ts
@@ -511,7 +511,11 @@ export class PiWebApp extends LitElement {
     const panelContext = workspace === undefined ? undefined : this.createWorkspacePanelContext(workspace);
     const workspaceLabelItems = workspace === undefined ? [] : this.plugins.getWorkspaceLabelItems(this.state, workspace);
     const emptyState = workspace === undefined ? this.workspacePanelEmptyState() : undefined;
-    return html`<workspace-panel .workspace=${workspace} .panelContext=${panelContext} .emptyState=${emptyState} .tool=${this.state.workspaceTool} .panels=${this.visibleWorkspacePanels()} .workspaceLabelItems=${workspaceLabelItems} .onSelectTool=${(tool: QualifiedContributionId) => { this.openWorkspaceTool(tool); }}></workspace-panel>`;
+    return html`<workspace-panel .workspace=${workspace} .panelContext=${panelContext} .emptyState=${emptyState} .tool=${this.state.workspaceTool} .panels=${this.visibleWorkspacePanels()} .workspaceLabelItems=${workspaceLabelItems} .collapsed=${this.state.workspacePanelCollapsed} .onSelectTool=${(tool: QualifiedContributionId) => { this.openWorkspaceTool(tool); }} .onToggleCollapse=${() => { this.toggleWorkspacePanelCollapse(); }}></workspace-panel>`;
+  }
+
+  private toggleWorkspacePanelCollapse(): void {
+    this.setState({ workspacePanelCollapsed: !this.state.workspacePanelCollapsed });
   }
 
   private renderNavigationPanel(autoSwitchToChat: boolean) {
@@ -1192,10 +1196,11 @@ export class PiWebApp extends LitElement {
   override render() {
     const state = this.state;
     return html`
-      <div class=${`shell ${state.mainView === "navigation" ? "navigation-view" : state.mainView === "chat" ? "chat-view" : "workspace-view"}`}>
+      <div class=${`shell ${state.mainView === "navigation" ? "navigation-view" : state.mainView === "chat" ? "chat-view" : "workspace-view"}${state.workspacePanelCollapsed ? " workspace-panel-collapsed" : ""}`}>
         <aside>${this.isMobileNavigationLayout ? null : this.renderNavigationPanel(false)}</aside>
         <main class=${state.mainView === "chat" ? "chat-view" : state.mainView === "navigation" ? "navigation-view" : "workspace-view"}>
           ${this.renderContextBar()}
+          ${state.workspacePanelCollapsed ? html`<div class="expand-panel-strip"><button class="expand-workspace-panel-button" title="Expand workspace panel" aria-label="Expand workspace panel" @click=${() => { this.toggleWorkspacePanelCollapse(); }}><svg class="expand-icon" viewBox="0 0 24 24" aria-hidden="true" focusable="false"><path d="M15 18l-6-6 6-6"/></svg></button></div>` : null}
           <div class=${this.mobileTabsFrameClass()}>
             <div class="mobile-tabs" @scroll=${this.onMobileTabsScroll}>
               <button class=${state.mainView === "navigation" ? "mobile-navigation-tab selected" : "mobile-navigation-tab"} @click=${() => { this.selectMainView("navigation"); }}>Sessions</button>
diff --git a/src/client/src/components/WorkspacePanel.ts b/src/client/src/components/WorkspacePanel.ts
index 826b293..11d5e75 100644
--- a/src/client/src/components/WorkspacePanel.ts
+++ b/src/client/src/components/WorkspacePanel.ts
@@ -19,7 +19,9 @@ export class WorkspacePanel extends LitElement {
   @property({ attribute: false }) panels: QualifiedWorkspacePanelContribution[] = [];
   @property({ attribute: false }) workspaceLabelItems: WorkspaceLabelItem[] = [];
   @property({ type: Boolean }) hideToolTabs = false;
+  @property({ type: Boolean }) collapsed = false;
   @property({ attribute: false }) onSelectTool: (tool: QualifiedContributionId) => void = () => undefined;
+  @property({ attribute: false }) onToggleCollapse: () => void = () => undefined;
   @query(".workspace-header-strip") private workspaceHeaderStrip?: HTMLElement | null;
   @state() private workspaceHeaderCanScrollLeft = false;
   @state() private workspaceHeaderCanScrollRight = false;
@@ -69,6 +71,7 @@ export class WorkspacePanel extends LitElement {
                 ${visiblePanels.map((panel) => html`
                   <button class=${selectedPanel?.id === panel.id ? "selected" : ""} @click=${() => { this.onSelectTool(panel.id); }}>${this.renderPanelTitle(panel, context)}</button>
                 `)}
+                <button class="collapse-button" title="Collapse panel" aria-label="Collapse panel" @click=${() => { this.onToggleCollapse(); }}>${this.renderCollapseIcon()}</button>
               </div>
             `}
             <small>${renderWorkspaceLabel(workspace.label, this.workspaceLabelItems, workspace.path)}</small>
@@ -92,6 +95,10 @@ export class WorkspacePanel extends LitElement {
     return html`${panel.title} <span class="tab-badge">${badge}</span>`;
   }
 
+  private renderCollapseIcon(): TemplateResult {
+    return html`<svg class="collapse-icon" viewBox="0 0 24 24" aria-hidden="true" focusable="false"><path d="M9 18l6-6-6-6"/></svg>`;
+  }
+
   private renderEmptyState(state: WorkspacePanelEmptyState): TemplateResult {
     return html`
       <section class="empty-state" role="status">
diff --git a/src/client/src/components/shared.ts b/src/client/src/components/shared.ts
index 41e06be..118a9b8 100644
--- a/src/client/src/components/shared.ts
+++ b/src/client/src/components/shared.ts
@@ -52,6 +52,8 @@ export interface CompletionItem {
 export const appStyles = css`
   :host { display: block; height: 100dvh; box-sizing: border-box; padding: env(safe-area-inset-top) env(safe-area-inset-right) env(safe-area-inset-bottom) env(safe-area-inset-left); color: var(--pi-text); background: var(--pi-bg); font: 14px system-ui, sans-serif; }
   .shell { display: grid; grid-template-columns: 340px minmax(420px, 1fr) minmax(360px, 42vw); height: 100%; min-height: 0; }
+  .shell.workspace-panel-collapsed { grid-template-columns: 340px minmax(420px, 1fr); }
+  .shell.workspace-panel-collapsed > workspace-panel { display: none; }
   aside { display: flex; flex-direction: column; min-height: 0; border-right: 1px solid var(--pi-border); overflow: hidden; }
   header { flex: 0 0 auto; display: flex; align-items: center; justify-content: space-between; gap: 8px; padding: 12px; border-bottom: 1px solid var(--pi-border); }
   .header-actions { display: flex; align-items: center; gap: 8px; }
@@ -93,6 +95,9 @@ export const appStyles = css`
   .mobile-navigation-tab, .mobile-navigation-panel { display: none; }
   .mobile-tabs button.selected { border-color: var(--pi-accent); background: var(--pi-selection-bg); }
   .tab-badge { display: inline-block; min-width: 14px; margin-left: 4px; border: 1px solid var(--pi-success-border); border-radius: 999px; background: var(--pi-success-surface); color: var(--pi-success); padding: 0 5px; font-size: 11px; line-height: 16px; text-align: center; }
+  .expand-panel-strip { flex: 0 0 auto; display: flex; align-items: center; padding: 4px 8px; border-bottom: 1px solid var(--pi-border-muted); }
+  .expand-workspace-panel-button { display: inline-flex; align-items: center; justify-content: center; width: 30px; height: 30px; padding: 0; border-radius: 6px; }
+  .expand-workspace-panel-button .expand-icon { width: 14px; height: 14px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; pointer-events: none; }
   workspace-panel { min-width: 0; min-height: 0; border-left: 1px solid var(--pi-border); overflow: hidden; }
   @media (max-width: 1180px) {
     .shell { grid-template-columns: 340px minmax(0, 1fr); grid-template-rows: auto minmax(0, 1fr); }
@@ -102,6 +107,8 @@ export const appStyles = css`
     .shell.workspace-view main { grid-row: 1; min-height: auto; }
     .shell.workspace-view > workspace-panel { grid-column: 2; grid-row: 2; display: flex; border-left: 0; }
     .shell:not(.workspace-view) > workspace-panel { display: none; }
+    .shell.workspace-panel-collapsed > workspace-panel { display: none; }
+    .shell.workspace-panel-collapsed .expand-panel-strip { display: flex; }
     main.workspace-view chat-view, main.workspace-view prompt-editor, main.workspace-view status-bar,
     main.workspace-view .empty { display: none; }
     main.workspace-view { overflow: hidden; }
@@ -140,8 +147,10 @@ export const workspacePanelStyles = css`
   .workspace-header-scroll-frame::after { right: 0; background: linear-gradient(270deg, color-mix(in srgb, var(--pi-shadow-strong) 55%, transparent) 0%, transparent 100%); }
   .workspace-header-scroll-frame.can-scroll-left::before, .workspace-header-scroll-frame.can-scroll-right::after { opacity: 1; }
   .workspace-header-strip { display: flex; justify-content: space-between; align-items: center; gap: 8px; min-width: 0; padding: 8px; overflow-x: auto; overflow-y: hidden; overscroll-behavior-x: contain; scrollbar-width: thin; }
-  .tabs { flex: 0 0 auto; display: flex; gap: 6px; }
+  .tabs { flex: 0 0 auto; display: flex; gap: 6px; align-items: center; }
   .tabs button { flex: 0 0 auto; white-space: nowrap; }
+  .collapse-button { display: inline-flex; align-items: center; justify-content: center; width: auto; height: auto; padding: 5px 7px; }
+  .collapse-icon { width: 14px; height: 14px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; pointer-events: none; }
   button { display: inline-flex; align-items: center; gap: 5px; border: 1px solid var(--pi-border); border-radius: 7px; background: var(--pi-surface); color: var(--pi-text); padding: 5px 7px; cursor: pointer; }
   button.selected { border-color: var(--pi-accent); background: var(--pi-selection-bg); }
   .tab-badge { display: inline-block; min-width: 14px; border: 1px solid var(--pi-success-border); border-radius: 999px; background: var(--pi-success-surface); color: var(--pi-success); padding: 0 5px; font-size: 11px; line-height: 16px; text-align: center; }