diff --git a/apps/web/src/components/panes/TerminalPane.tsx b/apps/web/src/components/panes/TerminalPane.tsx
index 8f8af6e..f765eb7 100644
--- a/apps/web/src/components/panes/TerminalPane.tsx
+++ b/apps/web/src/components/panes/TerminalPane.tsx
@@ -184,8 +184,35 @@ export function TerminalPane({ sessionId, paneId, label, active = false }: Props
     term.loadAddon(search);
     term.loadAddon(new WebLinksAddon());
     term.open(container);
+    // v1.10.4 gap fix: bypass FitAddon's proposeDimensions(), which subtracts
+    // a phantom scrollbar width even when CSS hides the scrollbar. Compute
+    // cols/rows directly from the host's clientWidth/clientHeight divided by
+    // the renderer's reported cell size. Falls back to FitAddon if cell
+    // metrics aren't ready yet (e.g. on very first mount).
+    const fitFull = (): void => {
+      const host = containerRef.current;
+      const t = termRef.current;
+      if (!host || !t) return;
+      if (!t.element || !(t.element as HTMLElement).offsetParent) return;
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      const core: any = (t as any)._core;
+      const cellW: number | undefined = core?._renderService?.dimensions?.css?.cell?.width;
+      const cellH: number | undefined = core?._renderService?.dimensions?.css?.cell?.height;
+      if (!cellW || !cellH || cellW <= 0 || cellH <= 0) {
+        try { fit.fit(); } catch { /* not ready */ }
+        return;
+      }
+      const cols = Math.max(2, Math.floor(host.clientWidth / cellW));
+      const rows = Math.max(1, Math.floor(host.clientHeight / cellH));
+      if (cols !== t.cols || rows !== t.rows) {
+        try { t.resize(cols, rows); } catch { /* ignore */ }
+      }
+    };
+
     try {
-      fit.fit();
+      fitFull();
+      // v1.10.4: also push initial size to PTY so opencode/bash get correct cols/rows
+      api.terminals.resize(sessionId, paneId, term.cols, term.rows).catch(() => {});
     } catch {
       /* container not yet sized */
     }
@@ -199,7 +226,8 @@ export function TerminalPane({ sessionId, paneId, label, active = false }: Props
         .then(() => {
           if (disposed) return;
           try {
-            fit.fit();
+            fitFull();
+            api.terminals.resize(sessionId, paneId, term.cols, term.rows).catch(() => {});
           } catch {
             /* ignore */
           }
@@ -363,7 +391,7 @@ export function TerminalPane({ sessionId, paneId, label, active = false }: Props
 
     const fireResize = (): void => {
       try {
-        fit.fit();
+        fitFull();
       } catch {
         return;
       }