diff --git a/.github/scripts/sync-agent.test.ts b/.github/scripts/sync-agent.test.ts
index 8db92aa61c..cb8a51aa18 100644
--- a/.github/scripts/sync-agent.test.ts
+++ b/.github/scripts/sync-agent.test.ts
@@ -7,6 +7,7 @@ import { type CheckRun, REQUIRED_CHECKS } from "./fast-forward.ts";
 import { createTestRepo, git, type TestRepo } from "./promotion-test-repo.ts";
 import {
   buildSuggestions,
+  failureExcerpt,
   leftoverConflictMarkers,
   planRepair,
   type ReviewThread,
@@ -340,3 +341,24 @@ describe("leftoverConflictMarkers", () => {
     }
   });
 });
+
+test("failure excerpt keeps an early test failure that the log tail would drop", () => {
+  const log = [
+    "2026-10-13T10:48:27.3385710Z supabase:test:integration: \x1b[41m FAIL \x1b[49m src/signing-key.integration.test.ts > flushes telemetry",
+    "2026-10-13T10:48:27.3386440Z AssertionError: expected 'supabase/.env' to be '.env'",
+    ...Array.from(
+      { length: 1000 },
+      (_, index) => `2026-10-13T10:49:30.0000000Z stack output ${index}`,
+    ),
+    "2026-10-13T10:49:31.0000000Z ##[error]Process completed with exit code 1.",
+  ].join("\n");
+
+  const excerpt = failureExcerpt(log);
+
+  expect(excerpt).toContain("AssertionError: expected 'supabase/.env' to be '.env'");
+  expect(excerpt).toContain("##[error]Process completed with exit code 1.");
+  expect(excerpt).not.toContain("stack output 100\n");
+  expect(excerpt).toContain("[...]");
+  expect(excerpt).not.toContain("\x1b");
+  expect(excerpt).not.toMatch(/^\S+Z /m);
+});
diff --git a/.github/scripts/sync-agent.ts b/.github/scripts/sync-agent.ts
index 77fe12a382..b5427aa171 100644
--- a/.github/scripts/sync-agent.ts
+++ b/.github/scripts/sync-agent.ts
@@ -584,7 +584,11 @@ async function fetchOpenFindings(
   });
 }
 
-async function logTail(token: string, repository: string, jobId: number): Promise<string> {
+async function jobFailureExcerpt(
+  token: string,
+  repository: string,
+  jobId: number,
+): Promise<string> {
   const response = await fetch(
     `https://api.github.com/repos/${repository}/actions/jobs/${jobId}/logs`,
     {
@@ -594,7 +598,46 @@ async function logTail(token: string, repository: string, jobId: number): Promis
   if (!response.ok) {
     return `(log unavailable: ${response.status})`;
   }
-  return (await response.text()).split("\n").slice(-LOG_TAIL_LINES).join("\n");
+  return failureExcerpt(await response.text());
+}
+
+const ERROR_CONTEXT_LINES = 40;
+const MAX_ERROR_WINDOWS = 10;
+
+/**
+ * Keeps the lines after each error annotation plus the log tail, because Turbo interleaves packages and the failing
+ * one's output often ends long before the job does.
+ */
+export function failureExcerpt(log: string): string {
+  const lines = log
+    // oxlint-disable-next-line no-control-regex -- strips ANSI colour codes from job logs
+    .replace(/\x1b\[[0-9;]*m/g, "")
+    .split("\n")
+    .map((line) => line.replace(/^\S+Z /, ""));
+  const kept = new Set<number>();
+  let windows = 0;
+  lines.forEach((line, index) => {
+    // Turbo prefixes each line with its task name when it streams several packages.
+    if (windows < MAX_ERROR_WINDOWS && /^(\S+:\s)?\s*(##\[error\]|FAIL\s)/.test(line)) {
+      windows += 1;
+      for (let at = index; at < Math.min(index + ERROR_CONTEXT_LINES, lines.length); at += 1) {
+        kept.add(at);
+      }
+    }
+  });
+  for (let at = Math.max(0, lines.length - LOG_TAIL_LINES); at < lines.length; at += 1) {
+    kept.add(at);
+  }
+  let previous = -1;
+  const excerpt: string[] = [];
+  for (const index of [...kept].sort((a, b) => a - b)) {
+    if (index !== previous + 1) {
+      excerpt.push("[...]");
+    }
+    excerpt.push(lines[index] ?? "");
+    previous = index;
+  }
+  return excerpt.join("\n");
 }
 
 /** Whether an `AI Review` run for this pull request is queued or running; its run name carries the PR number. */
@@ -688,7 +731,7 @@ async function collect(outputDir: string): Promise<void> {
   const failures = await Promise.all(
     plan.failures.map(
       async (run) =>
-        `## ${run.name} (${run.conclusion})\n\n\`\`\`\`text\n${await logTail(token, repository, run.id)}\n\`\`\`\`\n`,
+        `## ${run.name} (${run.conclusion})\n\n\`\`\`\`text\n${await jobFailureExcerpt(token, repository, run.id)}\n\`\`\`\`\n`,
     ),
   );
   writeFileSync(join(contextDir, "ci-failures.md"), failures.join("\n") || "No CI job failed.\n");
diff --git a/.github/sync-branches/repair-prompt.md b/.github/sync-branches/repair-prompt.md
index 33b9622e3e..9c78ecd6e9 100644
--- a/.github/sync-branches/repair-prompt.md
+++ b/.github/sync-branches/repair-prompt.md
@@ -8,7 +8,7 @@ major; `next` collects breaking changes for the following major. The working dir
 sync branch: `develop` with `next` merged in and its conflicts already resolved, but some checks
 fail. Repository conventions live in `CLAUDE.md`, `AGENTS.md`, and `docs/adr/`. Read these first:
 
-- `ci-failures.md` in the added context directory: the failed checks and the end of their output.
+- `ci-failures.md` in the added context directory: the failed checks, the output after each error, and the end of their logs.
 - `review-findings.md` in the same directory: the AI review's open findings, numbered.
 
 ## Your task