diff --git a/openspec/changes/agent-codex-prevent-session-severity-help-and-test-d-2026-04-23-00-01/notes.md b/openspec/changes/agent-codex-prevent-session-severity-help-and-test-d-2026-04-23-00-01/notes.md
new file mode 100644
index 0000000..096c685
--- /dev/null
+++ b/openspec/changes/agent-codex-prevent-session-severity-help-and-test-d-2026-04-23-00-01/notes.md
@@ -0,0 +1,10 @@
+# agent-codex-prevent-session-severity-help-and-test-d-2026-04-23-00-01 (minimal / T1)
+
+- Move the `report session-severity` help contract into the report module so usage text, example args, and rubric summary come from the same source as the scorer.
+- Keep the scored-output assertions hard-coded in tests while reusing the shared example args, so score changes still break tests instead of silently updating expectations.
+- Add focused help coverage that proves the CLI help prints the shared session-severity contract text.
+- Verification:
+  - `node --test test/report.test.js test/cli-args-dispatch.test.js`
+  - `node bin/multiagent-safety.js report help`
+  - `node bin/multiagent-safety.js report session-severity --task-size narrow-patch --tokens 3850000 --exec-count 18 --write-stdin-count 6 --completion-before-tail yes --fragmentation 14 --finish-path 6 --post-proof 4`
+  - `git diff --check`
diff --git a/src/cli/main.js b/src/cli/main.js
index 434c55f..6c3ef05 100755
--- a/src/cli/main.js
+++ b/src/cli/main.js
@@ -2431,15 +2431,20 @@ function report(rawArgs) {
   const options = parseReportArgs(rawArgs);
   const subcommand = options.subcommand || 'help';
   if (subcommand === 'help' || subcommand === '--help' || subcommand === '-h') {
+    const sessionSeverityHelpDetails = sessionSeverityReport.renderSessionSeverityHelpDetails()
+      .split('\n')
+      .map((line) => `    ${line}`)
+      .join('\n');
     console.log(
       `${TOOL_NAME} report commands:\n` +
       `  ${TOOL_NAME} report scorecard [--target <path>] [--repo github.com/<owner>/<repo>] [--scorecard-json <file>] [--output-dir <path>] [--date YYYY-MM-DD] [--dry-run] [--json]\n` +
-      `  ${TOOL_NAME} report session-severity --task-size <narrow-patch|medium-change|large-change> --tokens <count> --exec-count <count> --write-stdin-count <count> --completion-before-tail <yes|no> [--expected-bound <count>] [--fragmentation <preset|0-25>] [--finish-path <preset|0-15>] [--post-proof <preset|0-15>] [--json]\n` +
+      `  ${sessionSeverityReport.renderSessionSeverityCommand(TOOL_NAME)}\n` +
+      `${sessionSeverityHelpDetails}\n` +
       `\n` +
       `Examples:\n` +
       `  ${TOOL_NAME} report scorecard --repo github.com/recodeecom/multiagent-safety\n` +
       `  ${TOOL_NAME} report scorecard --scorecard-json ./scorecard.json --date 2026-04-10\n` +
-      `  ${TOOL_NAME} report session-severity --task-size narrow-patch --tokens 3850000 --exec-count 18 --write-stdin-count 6 --completion-before-tail yes --fragmentation 14 --finish-path 6 --post-proof 4`,
+      `  ${sessionSeverityReport.renderSessionSeverityExample(TOOL_NAME)}`,
     );
     process.exitCode = 0;
     return;
diff --git a/src/report/session-severity.js b/src/report/session-severity.js
index 809c0e5..ee80bb1 100644
--- a/src/report/session-severity.js
+++ b/src/report/session-severity.js
@@ -4,7 +4,8 @@ const TASK_SIZE_UPPER_BOUNDS = {
   'large-change': 8_000_000,
 };
 
-const TASK_SIZE_VALUES = new Set(Object.keys(TASK_SIZE_UPPER_BOUNDS));
+const TASK_SIZE_VALUES = Object.keys(TASK_SIZE_UPPER_BOUNDS);
+const TASK_SIZE_SET = new Set(TASK_SIZE_VALUES);
 const FRAGMENTATION_PRESET_SCORES = {
   clean: 0,
   'few-extra-checks': 5,
@@ -32,6 +33,50 @@ const DRIVER_LABELS = {
   finishPath: 'finish-path discipline',
   postProof: 'post-proof drift',
 };
+const LABEL_BANDS = [
+  { max: 15, label: 'Healthy' },
+  { max: 30, label: 'Mildly fragmented' },
+  { max: 50, label: 'Inefficient' },
+  { max: 75, label: 'Runaway' },
+  { max: 100, label: 'Catastrophic' },
+];
+const SESSION_SEVERITY_SUBCOMMAND = 'session-severity';
+const SESSION_SEVERITY_USAGE_ARGS = [
+  `--task-size <${TASK_SIZE_VALUES.join('|')}>`,
+  '--tokens <count>',
+  '--exec-count <count>',
+  '--write-stdin-count <count>',
+  '--completion-before-tail <yes|no>',
+  '[--expected-bound <count>]',
+  `[--fragmentation <${Object.keys(FRAGMENTATION_PRESET_SCORES).join('|')}|0-25>]`,
+  `[--finish-path <${Object.keys(FINISH_PATH_PRESET_SCORES).join('|')}|0-15>]`,
+  `[--post-proof <${Object.keys(POST_PROOF_PRESET_SCORES).join('|')}|0-15>]`,
+  '[--json]',
+].join(' ');
+const SESSION_SEVERITY_COMMAND_TAIL = `${SESSION_SEVERITY_SUBCOMMAND} ${SESSION_SEVERITY_USAGE_ARGS}`;
+const SESSION_SEVERITY_EXAMPLE_ARGS = [
+  '--task-size',
+  'narrow-patch',
+  '--tokens',
+  '3850000',
+  '--exec-count',
+  '18',
+  '--write-stdin-count',
+  '6',
+  '--completion-before-tail',
+  'yes',
+  '--fragmentation',
+  '14',
+  '--finish-path',
+  '6',
+  '--post-proof',
+  '4',
+];
+const SESSION_SEVERITY_EXAMPLE_TAIL = `${SESSION_SEVERITY_SUBCOMMAND} ${SESSION_SEVERITY_EXAMPLE_ARGS.join(' ')}`;
+
+function formatInteger(value) {
+  return Number(value).toLocaleString('en-US');
+}
 
 function parseRequiredPositiveInteger(name, rawValue, { allowZero = true } = {}) {
   const parsed = Number.parseInt(String(rawValue || ''), 10);
@@ -58,8 +103,8 @@ function clampScore(value, min, max) {
 
 function parseTaskSize(rawTaskSize) {
   const normalized = String(rawTaskSize || '').trim();
-  if (!TASK_SIZE_VALUES.has(normalized)) {
-    throw new Error(`--task-size must be one of: ${Array.from(TASK_SIZE_VALUES).join(', ')}`);
+  if (!TASK_SIZE_SET.has(normalized)) {
+    throw new Error(`--task-size must be one of: ${TASK_SIZE_VALUES.join(', ')}`);
   }
   return normalized;
 }
@@ -123,11 +168,7 @@ function scorePostProof(completionBeforeTail, override) {
 }
 
 function labelForTotal(total) {
-  if (total <= 15) return 'Healthy';
-  if (total <= 30) return 'Mildly fragmented';
-  if (total <= 50) return 'Inefficient';
-  if (total <= 75) return 'Runaway';
-  return 'Catastrophic';
+  return LABEL_BANDS.find((band) => total <= band.max)?.label || LABEL_BANDS[LABEL_BANDS.length - 1].label;
 }
 
 function buildSessionSeverityReport(options) {
@@ -205,9 +246,37 @@ function renderSessionSeverityReport(report) {
   ].join('\n');
 }
 
+function renderSessionSeverityHelpDetails() {
+  const taskSizeDefaults = TASK_SIZE_VALUES
+    .map((taskSize) => `${taskSize}=${formatInteger(TASK_SIZE_UPPER_BOUNDS[taskSize])}`)
+    .join(', ');
+  const labelBands = LABEL_BANDS
+    .map((band, index) => {
+      const min = index === 0 ? 0 : LABEL_BANDS[index - 1].max + 1;
+      return `${band.label}=${min}-${band.max}`;
+    })
+    .join(', ');
+  return [`Task-size defaults: ${taskSizeDefaults}`, `Label bands: ${labelBands}`].join('\n');
+}
+
+function renderSessionSeverityCommand(toolName) {
+  return `${toolName} report ${SESSION_SEVERITY_COMMAND_TAIL}`;
+}
+
+function renderSessionSeverityExample(toolName) {
+  return `${toolName} report ${SESSION_SEVERITY_EXAMPLE_TAIL}`;
+}
+
 module.exports = {
+  LABEL_BANDS,
+  SESSION_SEVERITY_COMMAND_TAIL,
+  SESSION_SEVERITY_EXAMPLE_ARGS,
+  SESSION_SEVERITY_EXAMPLE_TAIL,
   TASK_SIZE_UPPER_BOUNDS,
   buildSessionSeverityReport,
   renderSessionSeverityReport,
+  renderSessionSeverityHelpDetails,
+  renderSessionSeverityCommand,
+  renderSessionSeverityExample,
   labelForTotal,
 };
diff --git a/test/report.test.js b/test/report.test.js
index 1f44a93..d50c518 100644
--- a/test/report.test.js
+++ b/test/report.test.js
@@ -60,6 +60,7 @@ const {
   sanitizeSlug,
   defineSpawnSuite,
 } = require('./helpers/install-test-helpers');
+const sessionSeverityReport = require('../src/report/session-severity');
 
 defineSpawnSuite('report integration suite', () => {
 
@@ -101,26 +102,7 @@ exit 1
 
 test('report session-severity prints the weighted rubric summary', () => {
   const repoDir = initRepo();
-  const result = runNode([
-    'report',
-    'session-severity',
-    '--task-size',
-    'narrow-patch',
-    '--tokens',
-    '3850000',
-    '--exec-count',
-    '18',
-    '--write-stdin-count',
-    '6',
-    '--completion-before-tail',
-    'yes',
-    '--fragmentation',
-    '14',
-    '--finish-path',
-    '6',
-    '--post-proof',
-    '4',
-  ], repoDir);
+  const result = runNode(['report', 'session-severity', ...sessionSeverityReport.SESSION_SEVERITY_EXAMPLE_ARGS], repoDir);
 
   assert.equal(result.status, 0, result.stderr || result.stdout);
   assert.match(result.stdout, /Score 44\/100 — Inefficient\./);
@@ -130,6 +112,19 @@ test('report session-severity prints the weighted rubric summary', () => {
   assert.match(result.stdout, /Total: 44/);
 });
 
+test('report help reuses the shared session-severity contract text', () => {
+  const repoDir = initRepo();
+  const result = runNode(['report', 'help'], repoDir);
+  const helpDetailLines = sessionSeverityReport.renderSessionSeverityHelpDetails().split('\n');
+
+  assert.equal(result.status, 0, result.stderr || result.stdout);
+  assert.match(result.stdout, new RegExp(escapeRegexLiteral(sessionSeverityReport.SESSION_SEVERITY_COMMAND_TAIL)));
+  assert.match(result.stdout, new RegExp(escapeRegexLiteral(sessionSeverityReport.SESSION_SEVERITY_EXAMPLE_TAIL)));
+  for (const line of helpDetailLines) {
+    assert.match(result.stdout, new RegExp(escapeRegexLiteral(line)));
+  }
+});
+
 test('report session-severity emits structured JSON when requested', () => {
   const repoDir = initRepo();
   const result = runNode([