diff --git a/packages/session-ui/component-tests/session-tool-projection.spec.ts b/packages/session-ui/component-tests/session-tool-projection.spec.ts
index 7b9e77bd52c..d0f0ad9f174 100644
--- a/packages/session-ui/component-tests/session-tool-projection.spec.ts
+++ b/packages/session-ui/component-tests/session-tool-projection.spec.ts
@@ -179,6 +179,35 @@ story("opens an execution's code and output from its View code action", async ({
   await expect(dialog.getByRole("button", { name: "Copy output" })).toBeVisible()
 })
 
+story("wraps execute details code, pads it evenly, and starts line numbers near the block edge", async ({ mount }) => {
+  const timeline = await mount("current-session-terminal-work--execute-code")
+  const tool = timeline.locator('[data-timeline-part-id="tool_execute_long_call"]')
+  await tool.hover()
+  await tool.getByRole("button", { name: "View code" }).click()
+  const source = timeline.page().getByRole("dialog").locator('[data-slot="execute-details-source"]').first()
+  await expect(source.locator("[data-column-number]").first()).toBeVisible()
+
+  const layout = await source.evaluate((element) => {
+    const root = element.querySelector("diffs-container")!.shadowRoot!
+    const code = root.querySelector<HTMLElement>("[data-code]")!
+    const number = root.querySelector("[data-line-number-content]")!
+    const lines = [...root.querySelectorAll("[data-line]")].map((line) => line.getBoundingClientRect())
+    const box = element.getBoundingClientRect()
+    return {
+      paddingTop: lines[0].top - box.top,
+      paddingBottom: box.bottom - lines.at(-1)!.bottom,
+      // A horizontally scrolling block reserves a scrollbar track under a single line.
+      overflow: code.scrollWidth - code.clientWidth,
+      numberStart: number.getBoundingClientRect().left - box.left,
+    }
+  })
+
+  expect(layout.overflow).toBe(0)
+  expect(layout.numberStart).toBe(12)
+  expect(layout.paddingTop).toBe(4)
+  expect(layout.paddingBottom).toBe(4)
+})
+
 story("reveals the View code action while hovering anywhere over the execution", async ({ mount }) => {
   const timeline = await mount("current-session-terminal-work--execute-code")
   const tool = timeline.locator('[data-timeline-part-id="tool_execute_long_call"]')
diff --git a/packages/session-ui/src/components/message-part.css b/packages/session-ui/src/components/message-part.css
index 02f1fcf79ea..3810108c459 100644
--- a/packages/session-ui/src/components/message-part.css
+++ b/packages/session-ui/src/components/message-part.css
@@ -964,6 +964,15 @@
     overflow: auto;
     border-radius: 8px;
     box-shadow: 0 0 0 0.5px var(--v2-border-border-base);
+
+    /* The file wrapper sets Pierre's defaults inline, so override them on the shadow host below that wrapper. */
+    diffs-container {
+      --diffs-min-number-column-width: var(--execute-details-number-width, 1ch);
+      --opencode-diffs-number-inset: 12px;
+      --diffs-gap-block: 4px;
+      /* Wrapped blocks never scroll sideways; Pierre would otherwise subtract a scrollbar track from the bottom gap. */
+      --diffs-scrollbar-gutter-override: 0px;
+    }
   }
 
   [data-slot="execute-details-error"] {
diff --git a/packages/session-ui/src/pierre/index.ts b/packages/session-ui/src/pierre/index.ts
index 315890d0672..a1607ed36a6 100644
--- a/packages/session-ui/src/pierre/index.ts
+++ b/packages/session-ui/src/pierre/index.ts
@@ -234,6 +234,11 @@ const unsafeCSS = `
   );
 }
 
+/* Pierre insets line numbers by 2ch to leave room for diff change bars; compact file viewers can tighten it. */
+[data-file]:not([data-disable-line-numbers]) :is([data-column-number], [data-gutter-buffer]) {
+  padding-left: var(--opencode-diffs-number-inset, 2ch);
+}
+
 [data-diff-header],
 [data-diff],
 [data-file] {
diff --git a/packages/session-ui/src/tools/tool-renderer.tsx b/packages/session-ui/src/tools/tool-renderer.tsx
index 86ffc73a6cb..6381d13ab38 100644
--- a/packages/session-ui/src/tools/tool-renderer.tsx
+++ b/packages/session-ui/src/tools/tool-renderer.tsx
@@ -1976,7 +1976,11 @@ const decodeJson = Schema.decodeUnknownOption(Schema.fromJsonString(Schema.Unkno
 function ExecuteDetails(props: { code: string; output: string; error?: string; calls: number; status?: string }) {
   const i18n = useI18n()
   const fileComponent = useFileComponent()
-  const lines = (text: string) => i18n.plural("ui.tool.execute.lines", text.split("\n").length)
+  const lineCount = (text: string) => text.split("\n").length
+  const lines = (text: string) => i18n.plural("ui.tool.execute.lines", lineCount(text))
+  // Code and output share one number gutter, sized to the longer block, so their content starts on the same column.
+  const numberDigits = () =>
+    String(Math.max(lineCount(props.code), props.output && !props.error ? lineCount(props.output) : 0)).length
 
   return (
     <Dialog fit containerClass="!w-[min(calc(100vw_-_32px),720px)] max-h-[calc(100vh_-_92px)]">
@@ -1994,7 +1998,7 @@ function ExecuteDetails(props: { code: string; output: string; error?: string; c
         </div>
       </DialogHeader>
       <DialogBody class="min-h-0 flex-none overflow-y-auto">
-        <div data-component="execute-details">
+        <div data-component="execute-details" style={{ "--execute-details-number-width": `${numberDigits()}ch` }}>
           <ExecuteDetailsSection
             label={i18n.t("ui.tool.execute.code")}
             meta={lines(props.code)}
@@ -2005,7 +2009,7 @@ function ExecuteDetails(props: { code: string; output: string; error?: string; c
               component={fileComponent}
               mode="text"
               file={{ name: "execute.js", contents: props.code, cacheKey: checksum(props.code) }}
-              overflow="scroll"
+              overflow="wrap"
             />
           </ExecuteDetailsSection>
           <Show
@@ -2028,7 +2032,7 @@ function ExecuteDetails(props: { code: string; output: string; error?: string; c
                         contents: output(),
                         cacheKey: checksum(output()),
                       }}
-                      overflow="scroll"
+                      overflow="wrap"
                     />
                   </ExecuteDetailsSection>
                 )}