Improve action log step summary: 2-line tool previews and nicer agent messages by Copilot · Pull Request #24558 · github/gh-aw

Copilot · 2026-04-04T19:02:29Z

The step summary rendered only a single truncated line (or "X lines...") for tool output, and agent messages used a repetitive Agent: prefix on every line.

Changes

formatResultPreview() helper — new shared function that renders the first 2 non-empty lines of tool output using tree-branch characters:
```
✓ $ ls -la
   ├ file1.txt
   └ file2.txt (+ 1 more)
```
Single-line results still use └; exactly 2 lines use ├ + └; 3+ lines show (+ N more).
Agent message formatting — replaced per-line Agent: text with ◆ prefix on the first line and indent for continuation lines:
```
◆ I'll start by exploring the repository structure.
  Then check open issues and draft a plan.
```
Applied to both generateCopilotCliStyleSummary (step summary) and generatePlainTextSummary (console/core.info) for consistency.
Fixed conversationLineCount to count actual lines in multi-line preview strings rather than always incrementing by 1.

✨ PR Review Safe Output Test - Run 23985538383

💥 [THE END] — Illustrated by Smoke Claude · ● 317.3K · ◷

…r agent messages - Add formatResultPreview() helper that shows first 2 lines of tool output using tree-branch characters (├/└) for visual hierarchy - Update generateCopilotCliStyleSummary() to use new helper for all tool types - Update generatePlainTextSummary() to use new helper for all tool types - Change agent message prefix from "Agent: " (per-line) to "◆ " (first line) with " " indent for continuation lines, for a cleaner visual style - Count multi-line resultPreview accurately in conversationLineCount - Export formatResultPreview from module for potential reuse - Update all tests to match new formatting Agent-Logs-Url: https://github.com/github/gh-aw/sessions/e919a297-8597-4b17-97b2-aea5d6289e8b Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

…ilotCliStyleSummary Agent-Logs-Url: https://github.com/github/gh-aw/sessions/e919a297-8597-4b17-97b2-aea5d6289e8b Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

github-actions · 2026-04-04T19:04:14Z

🎬 THE END — Smoke Claude MISSION: ACCOMPLISHED! The hero saves the day! ✨

github-actions · 2026-04-04T19:04:15Z

📰 BREAKING: Smoke Copilot is now investigating this pull request. Sources say the story is developing...

github-actions · 2026-04-04T19:04:18Z

✅ All tools validated successfully! Agent Container Smoke Test confirms agent container is ready.

github-actions · 2026-04-04T19:04:31Z

🌑 The shadows whisper... Smoke Codex failed. The oracle requires further meditation...

Copilot

Pull request overview

This PR improves the readability/consistency of action log step summaries by rendering a 2-line preview for tool output and by simplifying agent message prefixes.

Changes:

Adds a shared formatResultPreview() helper to render the first 2 non-empty tool output lines with tree-branch formatting and a “(+ N more)” suffix.
Updates agent message formatting to use a single ◆ prefix for the first line and indentation for continuation lines.
Fixes conversation line counting to account for multi-line tool preview strings.

Show a summary per file

File	Description
actions/setup/js/log_parser_shared.cjs	Implements `formatResultPreview()`, updates agent message formatting, and applies 2-line tool previews + corrected line counting in both summary generators.
actions/setup/js/log_parser_shared.test.cjs	Updates summary expectations for the new agent prefix and 2-line tool preview behavior.
actions/setup/js/log_parser_bootstrap.test.cjs	Updates bootstrap test expectation for the new agent prefix in generated summaries.

Copilot's findings

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Files reviewed: 3/3 changed files
Comments generated: 3

Copilot · 2026-04-04T19:06:03Z

actions/setup/js/log_parser_shared.cjs

+ */
+function formatResultPreview(resultText, maxLineLength = 80) {
+  if (!resultText) return "";
+  const resultLines = resultText.split("\n").filter(l => l.trim());


formatResultPreview() splits only on "\n" and keeps the original line strings, so Windows-style CRLF output will leave trailing "\r" characters in the preview (can render as stray ^M or break alignment). Consider normalizing line endings (e.g., split on /\r?\n/ and/or strip a trailing \r from each line) before building the preview.

Suggested change

const resultLines = resultText.split("\n").filter(l => l.trim());

const resultLines = resultText.split(/\r?\n/).filter(l => l.trim());

Good catch! Normalizing CRLF line endings with /\r?\n/ is a solid defensive move for Windows-generated tool outputs.

📰 BREAKING: Report filed by Smoke Copilot · ● 697.8K

Copilot · 2026-04-04T19:06:03Z

actions/setup/js/log_parser_shared.cjs

+  const resultLines = resultText.split("\n").filter(l => l.trim());
+  if (resultLines.length === 0) return "";
+
+  const line1 = resultLines[0].substring(0, maxLineLength);
+  if (resultLines.length === 1) {
+    return `   └ ${line1}`;
+  }
+
+  const line2 = resultLines[1].substring(0, maxLineLength);
+  if (resultLines.length === 2) {
+    return `   ├ ${line1}\n   └ ${line2}`;
+  }
+
+  return `   ├ ${line1}\n   └ ${line2} (+ ${resultLines.length - 2} more)`;


formatResultPreview() uses resultText.split("\n").filter(...), which allocates an array of all lines even though the summary only needs the first two non-empty lines and a count. For very large tool outputs this can create avoidable memory pressure; consider scanning the string line-by-line and collecting the first 2 non-empty lines while counting the remainder without building a full array.

Suggested change

const resultLines = resultText.split("\n").filter(l => l.trim());

if (resultLines.length === 0) return "";

const line1 = resultLines[0].substring(0, maxLineLength);

if (resultLines.length === 1) {

return ` └ ${line1}`;

}

const line2 = resultLines[1].substring(0, maxLineLength);

if (resultLines.length === 2) {

return ` ├ ${line1}\n └ ${line2}`;

}

return ` ├ ${line1}\n └ ${line2} (+ ${resultLines.length - 2} more)`;

let firstLine = "";

let secondLine = "";

let nonEmptyLineCount = 0;

let start = 0;

while (start <= resultText.length) {

const newlineIndex = resultText.indexOf("\n", start);

const end = newlineIndex === -1 ? resultText.length : newlineIndex;

const line = resultText.substring(start, end);

if (line.trim()) {

nonEmptyLineCount += 1;

if (nonEmptyLineCount === 1) {

firstLine = line.substring(0, maxLineLength);

} else if (nonEmptyLineCount === 2) {

secondLine = line.substring(0, maxLineLength);

}

}

if (newlineIndex === -1) {

break;

}

start = newlineIndex + 1;

}

if (nonEmptyLineCount === 0) return "";

if (nonEmptyLineCount === 1) {

return ` └ ${firstLine}`;

}

if (nonEmptyLineCount === 2) {

return ` ├ ${firstLine}\n └ ${secondLine}`;

}

return ` ├ ${firstLine}\n └ ${secondLine} (+ ${nonEmptyLineCount - 2} more)`;

Copilot · 2026-04-04T19:06:03Z

actions/setup/js/log_parser_shared.cjs

+  const line1 = resultLines[0].substring(0, maxLineLength);
+  if (resultLines.length === 1) {
+    return `   └ ${line1}`;
+  }
+
+  const line2 = resultLines[1].substring(0, maxLineLength);
+  if (resultLines.length === 2) {


Preview lines are truncated with substring(0, maxLineLength) but no ellipsis/indicator is added when truncation occurs. Previously some tool previews appended "..." when exceeding 80 chars; adding a truncation marker would make cut-offs explicit and avoid confusing partial values in the summary.

github-actions · 2026-04-04T19:07:14Z

Agent Container Tool Check

Tool	Status	Version
bash	✅	5.2.21
sh	✅	available
git	✅	2.53.0
jq	✅	1.7
yq	✅	4.52.5
curl	✅	8.5.0
gh	✅	2.89.0
node	✅	20.20.2
python3	✅	3.12.3
go	✅	1.24.13
java	✅	21.0.10 (Temurin)
dotnet	✅	10.0.201

Result: 12/12 tools available ✅

Overall Status: PASS

🔧 Tool validation by Agent Container Smoke Test · ● 198.8K · ◷

github-actions · 2026-04-04T19:10:02Z

✅ Smoke test 23985538357 — Copilot engine\n\n| Test | ||\n|---|---|\n| GitHub MCP | ✅ |\n| MCP Scripts GH CLI | ✅ |\n| Playwright | ✅ |\n| Web Fetch | ✅ |\n| File Write/Read | ✅ |\n| Build | ✅ |\n| Discussion + PR Review | ✅ |\n\nOverall: PASS @pelikhan

📰 BREAKING: Report filed by Smoke Copilot · ● 697.8K · ◷

github-actions

Clean refactor extracting formatResultPreview() and upgrading agent message formatting. The ◆ prefix and tree-branch style (├/└) are a nice touch for readability. Bug fix for multi-line conversationLineCount is correct.

📰 BREAKING: Report filed by Smoke Copilot · ● 697.8K

github-actions · 2026-04-04T19:10:06Z

actions/setup/js/log_parser_shared.cjs

+ */
+function formatResultPreview(resultText, maxLineLength = 80) {
+  if (!resultText) return "";
+  const resultLines = resultText.split("\n").filter(l => l.trim());


The new formatResultPreview function looks clean! The ◆ prefix for agent messages and tree-branch style (├/└) for tool results is a nice visual improvement over the old Agent: prefix. Good use of the extracted helper to reduce duplication across 3 call sites.

github-actions · 2026-04-04T19:10:06Z

actions/setup/js/log_parser_shared.cjs

          if (resultPreview) {
            lines.push(resultPreview);
-            conversationLineCount++;
+            conversationLineCount += resultPreview.split("\n").length;


The conversationLineCount += resultPreview.split("\n").length fix is correct — previously only 1 line was counted even for multi-line previews, which could cause premature truncation of the conversation log.

github-actions · 2026-04-04T19:10:32Z

📰 VERDICT: Smoke Copilot has concluded. All systems operational. This is a developing story. 🎤

pelikhan · 2026-04-04T19:12:39Z

@copilot review comments

github-actions · 2026-04-04T19:12:41Z

Smoke Test Run 23985538383 Results

Overall: PARTIAL (Tavily 429)

💥 [THE END] — Illustrated by Smoke Claude · ● 317.3K · ◷

github-actions

💥 Automated smoke test review - all systems nominal!

💥 [THE END] — Illustrated by Smoke Claude · ● 317.3K

github-actions · 2026-04-04T19:12:43Z

actions/setup/js/log_parser_shared.cjs

+ * @param {number} [maxLineLength=80] - Maximum characters per preview line
+ * @returns {string} Formatted preview string, or empty string if no content
+ */
+function formatResultPreview(resultText, maxLineLength = 80) {


Nice addition of formatResultPreview as a reusable helper! Extracting this into its own function makes it much cleaner than the duplicated inline logic that existed before. The tree-branch characters (├, └) give a nice visual hierarchy consistent with copilot-cli style.

github-actions · 2026-04-04T19:12:43Z

actions/setup/js/log_parser_shared.test.cjs

@@ -1742,9 +1742,9 @@ describe("log_parser_shared.cjs", () => {
      const result = generatePlainTextSummary(logEntries, { parserName: "Agent" });

      expect(result).toContain("Conversation:");


The updated test expectations correctly reflect the new ◆ prefix for agent messages instead of the old Agent: prefix. Good to see multi-line agent responses are tested here with the (two-space indent) for continuation lines.

…ning, truncation ellipsis - Normalize Windows CRLF line endings by stripping trailing \r from each line - Replace full array allocation with line-by-line scanning to avoid memory pressure for large tool outputs (only first 2 non-empty lines needed) - Add "..." ellipsis when a preview line is truncated at maxLineLength - Add 8 unit tests covering all new behaviours Agent-Logs-Url: https://github.com/github/gh-aw/sessions/b80da586-4cc8-45c6-9e54-a9d5876ffa93 Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Copilot · 2026-04-04T19:18:22Z

@copilot review comments

All three review comments addressed in c99c027:

CRLF handling — each scanned line has trailing \r stripped via .replace(/\r$/, "").
Memory efficiency — replaced the full split().filter() array with an explicit line-by-line scan using indexOf("\n", start), collecting only the first 2 non-empty lines and counting the rest.
Truncation ellipsis — lines truncated at maxLineLength now append "..." to make cut-offs explicit.

8 new unit tests cover all three behaviours (empty/whitespace input, CRLF endings, exact-length vs truncated lines, blank line skipping).

Copilot AI and others added 2 commits April 4, 2026 18:43

fix: remove extra blank line before Statistics comment in generateCop…

fc790bb

…ilotCliStyleSummary Agent-Logs-Url: https://github.com/github/gh-aw/sessions/e919a297-8597-4b17-97b2-aea5d6289e8b Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Copilot AI assigned Copilot and pelikhan Apr 4, 2026

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pelikhan marked this pull request as ready for review April 4, 2026 19:02

Copilot AI review requested due to automatic review settings April 4, 2026 19:02

pelikhan added the smoke label Apr 4, 2026

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Smoke Test: Copilot - 23985538357 #24560

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Smoke Test: Claude - 23985538383 #24562

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Copilot finished work on behalf of pelikhan April 4, 2026 19:18

pelikhan merged commit b361d25 into main Apr 4, 2026

pelikhan deleted the copilot/update-action-log-rendering branch April 4, 2026 19:19

This was referenced Apr 4, 2026

Smoke Test: Copilot - 23985734485 #24563

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Smoke Test: Claude - 23985734470 #24565

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	const resultLines = resultText.split("\n").filter(l => l.trim());
	const resultLines = resultText.split(/\r?\n/).filter(l => l.trim());

-  const resultLines = resultText.split("\n").filter(l => l.trim());
-  if (resultLines.length === 0) return "";
-  const line1 = resultLines[0].substring(0, maxLineLength);
-  if (resultLines.length === 1) {
-    return `   └ ${line1}`;
-  }
-  const line2 = resultLines[1].substring(0, maxLineLength);
-  if (resultLines.length === 2) {
-    return `   ├ ${line1}\n   └ ${line2}`;
-  }
-  return `   ├ ${line1}\n   └ ${line2} (+ ${resultLines.length - 2} more)`;
+  let firstLine = "";
+  let secondLine = "";
+  let nonEmptyLineCount = 0;
+  let start = 0;
+  while (start <= resultText.length) {
+    const newlineIndex = resultText.indexOf("\n", start);
+    const end = newlineIndex === -1 ? resultText.length : newlineIndex;
+    const line = resultText.substring(start, end);
+    if (line.trim()) {
+      nonEmptyLineCount += 1;
+      if (nonEmptyLineCount === 1) {
+        firstLine = line.substring(0, maxLineLength);
+      } else if (nonEmptyLineCount === 2) {
+        secondLine = line.substring(0, maxLineLength);
+      }
+    }
+    if (newlineIndex === -1) {
+      break;
+    }
+    start = newlineIndex + 1;
+  }
+  if (nonEmptyLineCount === 0) return "";
+  if (nonEmptyLineCount === 1) {
+    return `   └ ${firstLine}`;
+  }
+  if (nonEmptyLineCount === 2) {
+    return `   ├ ${firstLine}\n   └ ${secondLine}`;
+  }
+  return `   ├ ${firstLine}\n   └ ${secondLine} (+ ${nonEmptyLineCount - 2} more)`;

		@@ -1742,9 +1742,9 @@ describe("log_parser_shared.cjs", () => {
		const result = generatePlainTextSummary(logEntries, { parserName: "Agent" });

		expect(result).toContain("Conversation:");

Conversation

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Agent Container Tool Check

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