diff --git a/docs/audits/terminal-wait-leading-blank/README.md b/docs/audits/terminal-wait-leading-blank/README.md
new file mode 100644
index 00000000000..959fde7c9af
--- /dev/null
+++ b/docs/audits/terminal-wait-leading-blank/README.md
@@ -0,0 +1,23 @@
+# Terminal wait tail-window termination
+
+`startOfLastNonBlankLines` loops indefinitely if its input begins with a newline and contains fewer nonblank rows than requested. Once the backward cursor reaches zero, JavaScript `lastIndexOf` clamps its negative start position to zero and rediscovers the same first newline. The cursor stops advancing.
+
+The fix ends the scan when the cursor reaches zero and returns the existing short-tail offset, zero. It changes no prompt patterns or readiness rules. The ordinary finite-window selection cases retain their previous offsets.
+
+## Reproduce
+
+```sh
+ORCA_BACKGROUND_LAUNCH=1 node docs/audits/terminal-wait-leading-blank/reproduce.mjs > /tmp/orca-terminal-wait-leading-blank.json
+```
+
+The script bundles actual source and reverses only the two-line termination change for the baseline. Each case runs in an isolated child with a two-second deadline and 128 MiB heap limit. The parent confirms child termination; no app windows open. Five direct helper/detector cases time out before and return after. A sufficient-row control and actual headless terminal projection controls pass in both variants. Results include source hashes, platform, timing, and an explicit v1.4.198 helper comparison.
+
+The regression suite uses a separate child for inputs that could hang the worker. It also tests exact row offsets with intervening whitespace, trailing blanks and tails shorter than the requested window. Fifty helper/detector tests pass.
+
+## Production and incident limits
+
+The helper is byte-identical in v1.4.198. However, all inspected main/provider/renderer visible-screen projection routes pass through `visibleNonBlankTerminalLines`, and ordinary retained-tail construction removes blank rows too. The real headless producer control confirms this filtering. Calling the public detector directly with a leading newline is therefore insufficient evidence that those production routes trigger the defect.
+
+A clipped 300-character preview can start at a newline. The preview fallback also preserves it when passed empty retained rows; the proof records both facts. It does not establish an actual application lifecycle that combines that fallback with a live detector call. That remains unproven.
+
+This is a defensive termination fix found during the memory audit. The loop itself does not allocate a growing collection. No memory magnitude was measured, and it is not an attribution of #19768's main-process growth or #19831's application-scope OOM.
diff --git a/docs/audits/terminal-wait-leading-blank/reproduce.mjs b/docs/audits/terminal-wait-leading-blank/reproduce.mjs
new file mode 100644
index 00000000000..6ee47701120
--- /dev/null
+++ b/docs/audits/terminal-wait-leading-blank/reproduce.mjs
@@ -0,0 +1,249 @@
+import { createHash } from 'node:crypto'
+import { mkdtemp, readFile, rm } from 'node:fs/promises'
+import { createRequire } from 'node:module'
+import { tmpdir } from 'node:os'
+import { join, resolve } from 'node:path'
+import { fileURLToPath } from 'node:url'
+import { isDeepStrictEqual } from 'node:util'
+import { build } from 'esbuild'
+
+if (process.env.ORCA_BACKGROUND_LAUNCH !== '1') {
+  throw new Error('Run with ORCA_BACKGROUND_LAUNCH=1.')
+}
+
+const root = fileURLToPath(new URL('../../../', import.meta.url))
+const sourcePath = 'src/main/runtime/terminal-wait-tail-window.ts'
+const absoluteSource = resolve(root, sourcePath)
+const current = await readFile(absoluteSource, 'utf8')
+const loop = '  while (lineEnd > 0) {'
+const end = '    lineEnd = lineStart - 1\n  }\n  return 0\n}'
+if (current.split(loop).length !== 2 || current.split(end).length !== 2) {
+  throw new Error('Source changed; review the baseline transform.')
+}
+const baseline = current
+  .replace(loop, '  for (;;) {')
+  .replace(end, '    lineEnd = lineStart - 1\n  }\n}')
+const sha256 = (value) => createHash('sha256').update(value).digest('hex')
+const supportingSources = [
+  'src/main/runtime/terminal-wait-detection.ts',
+  'src/main/runtime/orca-runtime-terminal-projection.ts',
+  'src/main/runtime/terminal-tail-read.ts',
+  'src/main/runtime/terminal-tail-state.ts',
+  'src/main/runtime/terminal-wait-tail-state.ts',
+  'src/main/daemon/headless-emulator.ts',
+  'src/main/runtime/terminal-wait-tail-window.test.ts'
+]
+const supportingSourceHashes = Object.fromEntries(
+  await Promise.all(
+    supportingSources.map(async (path) => [path, sha256(await readFile(resolve(root, path)))])
+  )
+)
+const scratch = await mkdtemp(join(tmpdir(), 'orca-terminal-wait-blank-'))
+const require = createRequire(import.meta.url)
+let runnerId
+
+try {
+  const runnerPath = join(scratch, 'run-process.cjs')
+  await build({
+    entryPoints: [resolve(root, 'src/shared/child-process/run-process.ts')],
+    outfile: runnerPath,
+    bundle: true,
+    platform: 'node',
+    format: 'cjs',
+    logLevel: 'silent'
+  })
+  runnerId = require.resolve(runnerPath)
+  const { runProcess } = require(runnerId)
+  const entry = `
+    import { startOfLastNonBlankLines } from './src/main/runtime/terminal-wait-tail-window';
+    import { detectTerminalWaitBlockedReason, isKnownReadyPromptPreview } from './src/main/runtime/terminal-wait-detection';
+    import { HeadlessEmulator } from './src/main/daemon/headless-emulator';
+    import { projectTerminalVisibleLines, projectTerminalTailLines } from './src/main/runtime/orca-runtime-terminal-projection';
+    import { buildPreview } from './src/main/runtime/terminal-tail-state';
+    import { buildTerminalWaitText } from './src/main/runtime/terminal-wait-tail-state';
+    const input = JSON.parse(process.argv[2]);
+    async function main() {
+      process.stdout.write(JSON.stringify({ phase: 'entered', mode: input.mode }) + '\\n');
+      let value;
+      if (input.mode === 'window') value = startOfLastNonBlankLines(input.text, input.count);
+      if (input.mode === 'blocked') value = detectTerminalWaitBlockedReason(input.text);
+      if (input.mode === 'ready') value = isKnownReadyPromptPreview(input.text);
+      if (input.mode === 'producer-controls') {
+        const emulator = new HeadlessEmulator({ cols: 80, rows: 12, scrollback: 0 });
+        try {
+          await emulator.write('\\r\\nordinary output\\r\\n');
+          const raw = emulator.getVisibleLines();
+          const visible = projectTerminalVisibleLines(emulator).lines;
+          const tail = projectTerminalTailLines(emulator, 12).lines;
+          const longLines = ['prefix', 'x'.repeat(299)];
+          const preview = buildPreview(longLines, '');
+          const waitText = buildTerminalWaitText(longLines, '', preview);
+          value = {
+            rawRowsStartBlank: raw[0] === '',
+            visibleRows: visible,
+            projectedTail: tail,
+            visibleClassification: detectTerminalWaitBlockedReason(visible.join('\\n')),
+            ordinaryTailClassification: detectTerminalWaitBlockedReason(buildTerminalWaitText(raw, '', '')),
+            clippedPreviewStartsNewline: preview.startsWith('\\n'),
+            retainedTailStartsNewline: waitText.startsWith('\\n'),
+            retainedTailClassification: detectTerminalWaitBlockedReason(waitText),
+            emptyTailFallbackStartsNewline: buildTerminalWaitText([], '', preview).startsWith('\\n')
+          };
+        } finally { emulator.dispose(); }
+      }
+      process.stdout.write(JSON.stringify({ phase: 'returned', value }) + '\\n');
+    }
+    main().catch(error => { process.stderr.write(String(error)); process.exitCode = 1; });
+  `
+  const cases = [
+    { name: 'leading newline only', mode: 'window', text: '\n', count: 12, expected: 0 },
+    { name: 'leading newline and text', mode: 'window', text: '\ntext', count: 12, expected: 0 },
+    { name: 'blank screen classification', mode: 'blocked', text: '\n\n', expected: null },
+    {
+      name: 'leading blank trust dialog',
+      mode: 'blocked',
+      text: '\nDo you trust this workspace directory?\n1. Yes\n2. No',
+      expected: 'agent-trust-workspace'
+    },
+    {
+      name: 'leading blank ready header',
+      mode: 'ready',
+      text: '\nOpenAI Codex\nmodel: test\ndirectory: /workspace',
+      expected: true
+    },
+    {
+      name: 'enough nonblank rows',
+      mode: 'window',
+      text: '\nfirst\nsecond',
+      count: 1,
+      expected: 7
+    },
+    {
+      name: 'production producer controls',
+      mode: 'producer-controls',
+      expected: {
+        rawRowsStartBlank: true,
+        visibleRows: ['ordinary output'],
+        projectedTail: ['ordinary output'],
+        visibleClassification: null,
+        ordinaryTailClassification: null,
+        clippedPreviewStartsNewline: true,
+        retainedTailStartsNewline: false,
+        retainedTailClassification: null,
+        emptyTailFallbackStartsNewline: true
+      }
+    }
+  ]
+  const results = {}
+  for (const [label, source] of Object.entries({ before: baseline, after: current })) {
+    const childPath = join(scratch, `${label}.cjs`)
+    await build({
+      stdin: { contents: entry, resolveDir: root },
+      outfile: childPath,
+      bundle: true,
+      platform: 'node',
+      format: 'cjs',
+      logLevel: 'silent',
+      plugins: [
+        {
+          name: 'terminal-wait-baseline',
+          setup(builder) {
+            builder.onLoad({ filter: /terminal-wait-tail-window\.ts$/ }, (args) =>
+              resolve(args.path) === absoluteSource ? { contents: source, loader: 'ts' } : null
+            )
+          }
+        }
+      ]
+    })
+    results[label] = []
+    for (const input of cases) {
+      let childTerminated = false
+      const started = performance.now()
+      const result = await runProcess({
+        program: process.execPath,
+        args: ['--max-old-space-size=128', childPath, JSON.stringify(input)],
+        env: { ...process.env, ORCA_BACKGROUND_LAUNCH: '1' },
+        timeoutMs: 2_000,
+        maxOutputBytes: 8192,
+        onChildTerminated: () => {
+          childTerminated = true
+        }
+      })
+      const output = result.stdout
+        .trim()
+        .split('\n')
+        .filter(Boolean)
+        .map((line) => JSON.parse(line))
+      const expectedTimeout = label === 'before' && cases.indexOf(input) < 5
+      const returned = output.find((event) => event.phase === 'returned')
+      if (
+        !childTerminated ||
+        result.timedOut !== expectedTimeout ||
+        !output.some((event) => event.phase === 'entered')
+      ) {
+        throw new Error(`Unexpected ${label} result for ${input.name}: ${JSON.stringify(result)}`)
+      }
+      if (
+        !expectedTimeout &&
+        (result.code !== 0 ||
+          !returned ||
+          ('expected' in input && !isDeepStrictEqual(returned.value, input.expected)))
+      ) {
+        throw new Error(
+          `Unexpected ${label} output for ${input.name}: ${result.stdout} ${result.stderr}`
+        )
+      }
+      results[label].push({
+        name: input.name,
+        timedOut: result.timedOut,
+        childTerminated,
+        code: result.code,
+        signal: result.signal,
+        elapsedMs: Math.round(performance.now() - started),
+        ...(returned ? { value: returned.value } : {})
+      })
+    }
+  }
+  const tag = await runProcess({
+    program: 'git',
+    args: ['show', `v1.4.198:${sourcePath}`],
+    cwd: root,
+    maxOutputBytes: 16_384
+  })
+  const provenance = await runProcess({
+    program: 'git',
+    args: ['rev-parse', 'HEAD'],
+    cwd: root,
+    maxOutputBytes: 1024
+  })
+  process.stdout.write(
+    `${JSON.stringify(
+      {
+        node: process.version,
+        platform: process.platform,
+        architecture: process.arch,
+        revision: provenance.stdout.trim(),
+        source: sourcePath,
+        hashes: {
+          before: sha256(baseline),
+          after: sha256(current),
+          reportedVersion: tag.code === 0 ? sha256(tag.stdout) : null
+        },
+        supportingSourceHashes,
+        reportedVersionSourceMatchesBaseline: tag.code === 0 && tag.stdout === baseline,
+        childTimeoutMs: 2000,
+        childHeapLimitMiB: 128,
+        scope:
+          'Helper termination and producer controls; no incident attribution or retained-byte claim.',
+        results
+      },
+      null,
+      2
+    )}\n`
+  )
+} finally {
+  if (runnerId) {
+    delete require.cache[runnerId]
+  }
+  await rm(scratch, { recursive: true, force: true })
+}
diff --git a/docs/audits/terminal-wait-leading-blank/results.json b/docs/audits/terminal-wait-leading-blank/results.json
new file mode 100644
index 00000000000..98776e8b5b8
--- /dev/null
+++ b/docs/audits/terminal-wait-leading-blank/results.json
@@ -0,0 +1,172 @@
+{
+  "node": "v26.6.0",
+  "platform": "darwin",
+  "architecture": "arm64",
+  "revision": "9558152a04c499c666192dd08906be8ada09e1dc",
+  "source": "src/main/runtime/terminal-wait-tail-window.ts",
+  "hashes": {
+    "before": "e6bc10e924d45bf4bfbd6fabf4404f160107cf7235b11c4e140cd6c78cff9146",
+    "after": "8df53ea8f92461549d727f251dae7cb4415d4208228ec5f60df9dcf13b863b86",
+    "reportedVersion": "e6bc10e924d45bf4bfbd6fabf4404f160107cf7235b11c4e140cd6c78cff9146"
+  },
+  "supportingSourceHashes": {
+    "src/main/runtime/terminal-wait-detection.ts": "226d09d2d8f7f1d692fb8ba1ed340818e6bd402b74d7bd98d86b1868a09503f0",
+    "src/main/runtime/orca-runtime-terminal-projection.ts": "70b815cf26864719b30b64845c0035093c16b9d85cb4bb8d25c4ae5fa63c3026",
+    "src/main/runtime/terminal-tail-read.ts": "3517bb22b9bf4bdf2f3acee8ceac9ca71221964cfa3f16be1f7b2ad22212b476",
+    "src/main/runtime/terminal-tail-state.ts": "a6f41a683d5f03023e4f6d20d653ebf069b036f82100c908a775a1890c49b2ef",
+    "src/main/runtime/terminal-wait-tail-state.ts": "61acc15fb8b9ce7faa0a2df80a7b6bae09dfed103c15b9c6c35a66d6ad585db1",
+    "src/main/daemon/headless-emulator.ts": "ace96102285c3967cd9544e7696fe73e1ac6df576b476939aa9819f5c298bab6",
+    "src/main/runtime/terminal-wait-tail-window.test.ts": "0faab1ca7b01e43ab555fd7fe2979975b818c22f25eca4f74dea3eb04f02c66b"
+  },
+  "reportedVersionSourceMatchesBaseline": true,
+  "childTimeoutMs": 2000,
+  "childHeapLimitMiB": 128,
+  "scope": "Helper termination and producer controls; no incident attribution or retained-byte claim.",
+  "results": {
+    "before": [
+      {
+        "name": "leading newline only",
+        "timedOut": true,
+        "childTerminated": true,
+        "code": null,
+        "signal": "SIGTERM",
+        "elapsedMs": 2004
+      },
+      {
+        "name": "leading newline and text",
+        "timedOut": true,
+        "childTerminated": true,
+        "code": null,
+        "signal": "SIGTERM",
+        "elapsedMs": 2002
+      },
+      {
+        "name": "blank screen classification",
+        "timedOut": true,
+        "childTerminated": true,
+        "code": null,
+        "signal": "SIGTERM",
+        "elapsedMs": 2002
+      },
+      {
+        "name": "leading blank trust dialog",
+        "timedOut": true,
+        "childTerminated": true,
+        "code": null,
+        "signal": "SIGTERM",
+        "elapsedMs": 2002
+      },
+      {
+        "name": "leading blank ready header",
+        "timedOut": true,
+        "childTerminated": true,
+        "code": null,
+        "signal": "SIGTERM",
+        "elapsedMs": 2002
+      },
+      {
+        "name": "enough nonblank rows",
+        "timedOut": false,
+        "childTerminated": true,
+        "code": 0,
+        "signal": null,
+        "elapsedMs": 32,
+        "value": 7
+      },
+      {
+        "name": "production producer controls",
+        "timedOut": false,
+        "childTerminated": true,
+        "code": 0,
+        "signal": null,
+        "elapsedMs": 36,
+        "value": {
+          "rawRowsStartBlank": true,
+          "visibleRows": ["ordinary output"],
+          "projectedTail": ["ordinary output"],
+          "visibleClassification": null,
+          "ordinaryTailClassification": null,
+          "clippedPreviewStartsNewline": true,
+          "retainedTailStartsNewline": false,
+          "retainedTailClassification": null,
+          "emptyTailFallbackStartsNewline": true
+        }
+      }
+    ],
+    "after": [
+      {
+        "name": "leading newline only",
+        "timedOut": false,
+        "childTerminated": true,
+        "code": 0,
+        "signal": null,
+        "elapsedMs": 34,
+        "value": 0
+      },
+      {
+        "name": "leading newline and text",
+        "timedOut": false,
+        "childTerminated": true,
+        "code": 0,
+        "signal": null,
+        "elapsedMs": 33,
+        "value": 0
+      },
+      {
+        "name": "blank screen classification",
+        "timedOut": false,
+        "childTerminated": true,
+        "code": 0,
+        "signal": null,
+        "elapsedMs": 33,
+        "value": null
+      },
+      {
+        "name": "leading blank trust dialog",
+        "timedOut": false,
+        "childTerminated": true,
+        "code": 0,
+        "signal": null,
+        "elapsedMs": 33,
+        "value": "agent-trust-workspace"
+      },
+      {
+        "name": "leading blank ready header",
+        "timedOut": false,
+        "childTerminated": true,
+        "code": 0,
+        "signal": null,
+        "elapsedMs": 33,
+        "value": true
+      },
+      {
+        "name": "enough nonblank rows",
+        "timedOut": false,
+        "childTerminated": true,
+        "code": 0,
+        "signal": null,
+        "elapsedMs": 32,
+        "value": 7
+      },
+      {
+        "name": "production producer controls",
+        "timedOut": false,
+        "childTerminated": true,
+        "code": 0,
+        "signal": null,
+        "elapsedMs": 37,
+        "value": {
+          "rawRowsStartBlank": true,
+          "visibleRows": ["ordinary output"],
+          "projectedTail": ["ordinary output"],
+          "visibleClassification": null,
+          "ordinaryTailClassification": null,
+          "clippedPreviewStartsNewline": true,
+          "retainedTailStartsNewline": false,
+          "retainedTailClassification": null,
+          "emptyTailFallbackStartsNewline": true
+        }
+      }
+    ]
+  }
+}
diff --git a/src/main/runtime/terminal-wait-tail-window.test.ts b/src/main/runtime/terminal-wait-tail-window.test.ts
new file mode 100644
index 00000000000..22a71140ee8
--- /dev/null
+++ b/src/main/runtime/terminal-wait-tail-window.test.ts
@@ -0,0 +1,77 @@
+import { mkdtemp, rm } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { build } from 'esbuild'
+import { afterAll, beforeAll, describe, expect, it } from 'vitest'
+import { runProcess } from '../../shared/child-process/run-process'
+import { startOfLastNonBlankLines } from './terminal-wait-tail-window'
+
+let scratch = ''
+let childPath = ''
+
+beforeAll(async () => {
+  scratch = await mkdtemp(join(tmpdir(), 'orca-tail-window-'))
+  childPath = join(scratch, 'leading-blank.cjs')
+  await build({
+    stdin: {
+      contents: `
+        import { startOfLastNonBlankLines } from './src/main/runtime/terminal-wait-tail-window';
+        import { detectTerminalWaitBlockedReason, isKnownReadyPromptPreview } from './src/main/runtime/terminal-wait-detection';
+        const tails = ['', '\\n', '\\n\\n', '\\ntext', '\\ntext\\n', '\\n \\t\\ntext\\n\\n'];
+        process.stdout.write(JSON.stringify({
+          offsets: tails.map(value => startOfLastNonBlankLines(value, 12)),
+          blank: detectTerminalWaitBlockedReason('\\n\\n'),
+          ordinary: detectTerminalWaitBlockedReason('\\nordinary output'),
+          blocked: detectTerminalWaitBlockedReason('\\nDo you trust this workspace directory?\\n1. Yes\\n2. No'),
+          ready: isKnownReadyPromptPreview('\\nOpenAI Codex\\nmodel: test\\ndirectory: /workspace')
+        }));
+      `,
+      resolveDir: process.cwd()
+    },
+    outfile: childPath,
+    bundle: true,
+    platform: 'node',
+    format: 'cjs',
+    logLevel: 'silent'
+  })
+})
+
+afterAll(async () => {
+  if (scratch) {
+    await rm(scratch, { recursive: true, force: true })
+  }
+})
+
+describe('terminal wait nonblank tail window', () => {
+  it('terminates on leading blank rows before classifying the remaining screen', async () => {
+    // Isolate the synchronous regression so its timeout cannot block the test worker.
+    const result = await runProcess({
+      program: process.execPath,
+      args: ['--max-old-space-size=64', childPath],
+      env: { ...process.env, ORCA_BACKGROUND_LAUNCH: '1' },
+      timeoutMs: 2_000,
+      maxOutputBytes: 4096
+    })
+    expect(result.timedOut).toBe(false)
+    expect(result.code, result.stderr).toBe(0)
+    expect(JSON.parse(result.stdout)).toEqual({
+      offsets: [0, 0, 0, 0, 0, 0],
+      blank: null,
+      ordinary: null,
+      blocked: 'agent-trust-workspace',
+      ready: true
+    })
+  })
+
+  it.each([
+    { value: 'first\nsecond\nthird', count: 2, expected: 'second\nthird' },
+    { value: 'first\n\n \t\nsecond\nthird\n', count: 2, expected: 'second\nthird\n' },
+    { value: '\nfirst\nsecond', count: 1, expected: 'second' },
+    { value: '\nfirst\nsecond', count: 2, expected: 'first\nsecond' },
+    { value: 'first\nsecond', count: 3, expected: 'first\nsecond' },
+    { value: 'first\nsecond\n\n', count: 1, expected: 'second\n\n' },
+    { value: ' \t\r\nsecond', count: 2, expected: ' \t\r\nsecond' }
+  ])('selects the last $count nonblank rows of $value', ({ value, count, expected }) => {
+    expect(value.slice(startOfLastNonBlankLines(value, count))).toBe(expected)
+  })
+})
diff --git a/src/main/runtime/terminal-wait-tail-window.ts b/src/main/runtime/terminal-wait-tail-window.ts
index 788000328f1..fec141f7cde 100644
--- a/src/main/runtime/terminal-wait-tail-window.ts
+++ b/src/main/runtime/terminal-wait-tail-window.ts
@@ -23,7 +23,7 @@ export function startOfLastLines(value: string, count: number): number {
 export function startOfLastNonBlankLines(value: string, count: number): number {
   let seen = 0
   let lineEnd = value.length
-  for (;;) {
+  while (lineEnd > 0) {
     const lineStart = value.lastIndexOf('\n', lineEnd - 1) + 1
     if (hasNonWhitespaceBetween(value, lineStart, lineEnd)) {
       seen += 1
@@ -36,6 +36,7 @@ export function startOfLastNonBlankLines(value: string, count: number): number {
     }
     lineEnd = lineStart - 1
   }
+  return 0
 }
 
 function hasNonWhitespaceBetween(value: string, start: number, end: number): boolean {