fix: clip a shell command to one line in a step title

src/ui/observability/wording.test.ts

@@ -0,0 +1,101 @@
+import { describe, expect, test } from "bun:test";
+
+import type { Span } from "./model.js";
+import { stepTitle } from "./wording.js";
+
+function toolSpan(input: string, label?: string): Span {
+  const span: Span = {
+    id: "span-1",
+    parentId: null,
+    kind: "tool",
+    name: "Bash",
+    status: "ok",
+    startMs: 0,
+    durationMs: 1,
+    input,
+  };
+  if (label === undefined) return span;
+  return { ...span, label };
+}
+
+describe("stepTitle", () => {
+  test("a label wins over the command", () => {
+    const input = JSON.stringify({ command: "ls -la" });
+    expect(stepTitle(toolSpan(input, "List files"))).toBe("List files");
+  });
+
+  test("a multiline command keeps the first line", () => {
+    const command = "git status\ngit diff";
+    const input = JSON.stringify({ command });
+    expect(stepTitle(toolSpan(input))).toBe("git status");
+    expect(JSON.parse(input).command).toBe(command);
+  });
+
+  test("a command of 80 characters stays whole", () => {
+    const command = "b".repeat(80);
+    const input = JSON.stringify({ cmd: command });
+    expect(stepTitle(toolSpan(input))).toBe(command);
+    expect(JSON.parse(input).cmd).toBe(command);
+  });
+
+  test("a blank command falls through to the step name", () => {
+    expect(stepTitle(toolSpan(JSON.stringify({ command: "  \nls" })))).toBe(
+      "Bash",
+    );
+  });
+
+  test("a longer command is clipped", () => {
+    const command = `  ${"a".repeat(90)}  \nrest`;
+    const input = JSON.stringify({ command });
+    expect(stepTitle(toolSpan(input))).toBe(`${"a".repeat(77)}…`);
+    expect(JSON.parse(input).command).toBe(command);
+  });
+
+  test("a command cut inside an emoji keeps the code point", () => {
+    const command = `${"a".repeat(76)}\u{1F600}${"b".repeat(20)}`;
+    const input = JSON.stringify({ command });
+    const span = toolSpan(input);
+    const title = stepTitle(span);
+    expect(title).toBe(`${"a".repeat(76)}\u{1F600}…`);
+    expect(title.endsWith("…")).toBe(true);
+    expect([...title].length).toBeLessThanOrEqual(78);
+    expect(loneSurrogate(title)).toBe(false);
+    expect(span.input).toBe(input);
+  });
+
+  test("a reasoning cut inside an emoji keeps the code point", () => {
+    const thinking = `${"c".repeat(84)}\u{1F600}${"d".repeat(20)}\nnext`;
+    const span: Span = {
+      id: "span-r",
+      parentId: null,
+      kind: "reasoning",
+      name: "Think",
+      status: "ok",
+      startMs: 0,
+      durationMs: 1,
+      thinking,
+    };
+    const title = stepTitle(span);
+    expect(title).toBe(`${"c".repeat(84)}\u{1F600}…`);
+    expect(title.endsWith("…")).toBe(true);
+    expect([...title].length).toBeLessThanOrEqual(86);
+    expect(loneSurrogate(title)).toBe(false);
+    expect(span.thinking).toBe(thinking);
+  });
+});
+
+function loneSurrogate(value: string): boolean {
+  for (let index = 0; index < value.length; index += 1) {
+    const code = value.charCodeAt(index);
+    const high = code >= 0xd800 && code <= 0xdbff;
+    const low = code >= 0xdc00 && code <= 0xdfff;
+    if (high) {
+      const next = value.charCodeAt(index + 1);
+      if (!(next >= 0xdc00 && next <= 0xdfff)) return true;
+      index += 1;
+      continue;
+    }
+    if (low) return true;
+  }
+  return false;
+}

src/ui/observability/wording.ts

@@ -21,7 +21,7 @@ export function stepTitle(span: Span): string {
   if (span.contextChange !== undefined) return span.contextChange.summary;
   if (span.kind === "reasoning" && span.thinking !== undefined) {
     const line = span.thinking.split("\n")[0] ?? span.thinking;
-    return line.length > 88 ? `${line.slice(0, 85)}…` : line;
+    return clipCodePoints(line, 88, 85);
   }
   return span.name;
 }
@@ -30,13 +30,27 @@ export function compactionLine(compaction: Compaction): string {
   return `${formatTokens(compaction.tokensBefore)} down to ${formatTokens(compaction.tokensAfter)}`;
 }
 
+function clipLine(value: string): string {
+  const first = value.split("\n")[0] ?? value;
+  return clipCodePoints(first.trim(), 80, 77);
+}
+
+function clipCodePoints(value: string, whole: number, keep: number): string {
+  const points = Array.from(value);
+  if (points.length <= whole) return value;
+  return `${points.slice(0, keep).join("")}…`;
+}
+
 function whatItDid(span: Span): string | undefined {
   const hop = span.network?.[0];
   if (hop !== undefined) return `${hop.method} ${shortUrl(hop.url)}`;
   const record = recordOf(span.input);
   if (record === undefined) return undefined;
   const command = text(record, "command") ?? text(record, "cmd");
-  if (command !== undefined) return command;
+  if (command !== undefined) {
+    const clipped = clipLine(command);
+    if (clipped.length > 0) return clipped;
+  }
   const pattern = text(record, "pattern");
   const path = text(record, "path") ?? text(record, "file");
   if (pattern !== undefined && !span.name.includes(pattern)) {

stories/observability/views/run.stories.tsx

@@ -96,6 +96,19 @@ SignalStory.storyName = "Signal";
 export const ToolStory = () => <Tool span={span("tool-shell", review)} />;
 ToolStory.storyName = "Tool";
 
+export const ClippedShellCommand = () => {
+  const command = [
+    "bun test src/parse.test.ts ".repeat(4).trimEnd(),
+    "echo done",
+  ].join("\n");
+  const shell = {
+    ...span("tool-shell", review),
+    input: JSON.stringify({ command }),
+  };
+  return <Tool span={shell} />;
+};
+ClippedShellCommand.storyName = "Clipped shell command";
+
 export const ThinkingStory = () => <Thinking span={span("e3", editor)} />;
 ThinkingStory.storyName = "Thinking";