diff --git a/src/constants.mjs b/src/constants.mjs
index 8e5a653..05748e2 100644
--- a/src/constants.mjs
+++ b/src/constants.mjs
@@ -21,6 +21,7 @@ export const DEFAULT_MAX_QUARANTINE_COOLDOWN_MS = 300_000;
 export const DEFAULT_SNAPSHOT_INTERVAL_MS = 60_000;
 export const VALID_CADENCES = new Set(['daily', 'weekly']);
 export const KIND_APP_DATA = 30078;
+export const MS_PER_SECOND = 1000;
 
 export const USAGE_TEXT = `Usage: torch-lock <command> [options]
 
diff --git a/src/context/CONTEXT_2026-02-19T21-26-08Z.md b/src/context/CONTEXT_2026-02-19T21-26-08Z.md
new file mode 100644
index 0000000..0a37d2c
--- /dev/null
+++ b/src/context/CONTEXT_2026-02-19T21-26-08Z.md
@@ -0,0 +1,5 @@
+# Context for Constant Refactor
+
+- **Goal:** Find and refactor duplicated numeric constants.
+- **Scope:** `src/` directory.
+- **Constraints:** Keep changes minimal and safe.
diff --git a/src/decisions/DECISIONS_2026-02-19T21-26-08Z.md b/src/decisions/DECISIONS_2026-02-19T21-26-08Z.md
new file mode 100644
index 0000000..a0f60e2
--- /dev/null
+++ b/src/decisions/DECISIONS_2026-02-19T21-26-08Z.md
@@ -0,0 +1,12 @@
+# 2026-02-19T21-26-08Z: Extracted MS_PER_SECOND
+
+## Decision
+Extracted `1000` (milliseconds per second) to `MS_PER_SECOND` constant in `src/constants.mjs`.
+
+## Rationale
+- Multiple files (`src/relay-health.mjs`, `src/utils.mjs`, `src/lib.mjs`, `src/lock-ops.mjs`) were using the literal `1000` for time conversion.
+- Using a named constant improves readability and maintainability.
+- Reduces risk of "magic number" confusion.
+
+## Alternatives Considered
+- Leaving as literal (rejected: hard to search/replace if logic changes, less semantic).
diff --git a/src/lib.mjs b/src/lib.mjs
index 1330522..08eb265 100644
--- a/src/lib.mjs
+++ b/src/lib.mjs
@@ -18,6 +18,7 @@ import {
   KIND_APP_DATA,
   RACE_CHECK_DELAY_MS,
   USAGE_TEXT,
+  MS_PER_SECOND,
 } from './constants.mjs';
 import { cmdInit, cmdUpdate } from './ops.mjs';
 import { parseArgs } from './cli-parser.mjs';
@@ -215,7 +216,7 @@ export async function cmdLock(agent, cadence, optionsOrDryRun = false, deps = {}
 
   error(`Locking: namespace=${namespace}, agent=${agent}, cadence=${cadence}, date=${dateStr}`);
   error(`Hashtag: #${hashtag}`);
-  error(`TTL: ${ttl}s, expires: ${new Date(expiresAt * 1000).toISOString()}`);
+  error(`TTL: ${ttl}s, expires: ${new Date(expiresAt * MS_PER_SECOND).toISOString()}`);
   error(`Relays: ${relays.join(', ')}`);
   if (gitCommit) error(`Git Commit: ${gitCommit}`);
   if (promptHash) error(`Prompt Hash: ${promptHash.slice(0, 12)}...`);
@@ -277,8 +278,8 @@ export async function cmdLock(agent, cadence, optionsOrDryRun = false, deps = {}
         date: dateStr,
         platform: platform || process.env.AGENT_PLATFORM || detectPlatform() || 'unknown',
         model: model || process.env.AGENT_MODEL || 'unknown',
-        lockedAt: new Date(now * 1000).toISOString(),
-        expiresAt: new Date(expiresAt * 1000).toISOString(),
+        lockedAt: new Date(now * MS_PER_SECOND).toISOString(),
+        expiresAt: new Date(expiresAt * MS_PER_SECOND).toISOString(),
         gitCommit,
         promptPath,
         promptHash,
@@ -326,7 +327,7 @@ export async function cmdLock(agent, cadence, optionsOrDryRun = false, deps = {}
   log(`LOCK_CADENCE=${cadence}`);
   log(`LOCK_DATE=${dateStr}`);
   log(`LOCK_EXPIRES=${expiresAt}`);
-  log(`LOCK_EXPIRES_ISO=${new Date(expiresAt * 1000).toISOString()}`);
+  log(`LOCK_EXPIRES_ISO=${new Date(expiresAt * MS_PER_SECOND).toISOString()}`);
   if (gitCommit) log(`LOCK_GIT_COMMIT=${gitCommit}`);
   if (promptHash) log(`LOCK_PROMPT_HASH=${promptHash}`);
   return { status: 'ok', eventId: event.id };
@@ -497,7 +498,7 @@ export async function cmdComplete(agent, cadence, optionsOrDryRun = false, deps
         platform: platform || process.env.AGENT_PLATFORM || detectPlatform() || 'unknown',
         model: model || process.env.AGENT_MODEL || 'unknown',
         startedAt: startedAtIso,
-        completedAt: new Date(now * 1000).toISOString(),
+        completedAt: new Date(now * MS_PER_SECOND).toISOString(),
       }),
     },
     sk,
diff --git a/src/lock-ops.mjs b/src/lock-ops.mjs
index 8b1830a..4408b5f 100644
--- a/src/lock-ops.mjs
+++ b/src/lock-ops.mjs
@@ -14,6 +14,7 @@ import {
   DEFAULT_QUARANTINE_COOLDOWN_MS,
   DEFAULT_MAX_QUARANTINE_COOLDOWN_MS,
   DEFAULT_SNAPSHOT_INTERVAL_MS,
+  MS_PER_SECOND,
 } from './constants.mjs';
 import { nowUnix } from './utils.mjs';
 
@@ -43,9 +44,9 @@ export function parseLockEvent(event) {
     eventId: event.id,
     pubkey: event.pubkey,
     createdAt: event.created_at,
-    createdAtIso: new Date(event.created_at * 1000).toISOString(),
+    createdAtIso: new Date(event.created_at * MS_PER_SECOND).toISOString(),
     expiresAt,
-    expiresAtIso: expiresAt ? new Date(expiresAt * 1000).toISOString() : null,
+    expiresAtIso: expiresAt ? new Date(expiresAt * MS_PER_SECOND).toISOString() : null,
     dTag,
     agent: content.agent ?? null,
     cadence: content.cadence ?? null,
diff --git a/src/relay-health.mjs b/src/relay-health.mjs
index 0c0a824..d1d8800 100644
--- a/src/relay-health.mjs
+++ b/src/relay-health.mjs
@@ -3,6 +3,7 @@ import path from 'node:path';
 import WebSocket from 'ws';
 import { finalizeEvent, generateSecretKey, getPublicKey } from 'nostr-tools/pure';
 import { getNamespace, getRelays } from './torch-config.mjs';
+import { MS_PER_SECOND } from './constants.mjs';
 
 const PROBE_KIND = 27235;
 
@@ -97,7 +98,7 @@ async function probePublishRead(relayUrl, namespace, timeoutMs) {
   const ws = new WebSocket(relayUrl);
   const sk = generateSecretKey();
   const pk = getPublicKey(sk);
-  const createdAt = Math.floor(Date.now() / 1000);
+  const createdAt = Math.floor(Date.now() / MS_PER_SECOND);
   const nonce = `${Date.now()}-${Math.random().toString(16).slice(2, 10)}`;
   const probeTag = `${namespace}-health-probe-${nonce}`;
   const event = finalizeEvent({
diff --git a/src/test_logs/TEST_LOG_2026-02-19T21-26-08Z.md b/src/test_logs/TEST_LOG_2026-02-19T21-26-08Z.md
new file mode 100644
index 0000000..e7a194f
--- /dev/null
+++ b/src/test_logs/TEST_LOG_2026-02-19T21-26-08Z.md
@@ -0,0 +1,8 @@
+- Command: npm run lint
+- Result: Passed
+
+- Command: npm run validate:scheduler-failure-schema
+- Result: Passed
+
+- Command: npm test
+- Result: Passed
diff --git a/src/todo/TODO_2026-02-19T21-26-08Z.md b/src/todo/TODO_2026-02-19T21-26-08Z.md
new file mode 100644
index 0000000..5d6cd63
--- /dev/null
+++ b/src/todo/TODO_2026-02-19T21-26-08Z.md
@@ -0,0 +1,7 @@
+# Pending
+
+- Identify more duplicated constants (e.g. `5000` for timeouts).
+
+# Completed
+
+- Refactored `1000` to `MS_PER_SECOND`.
diff --git a/src/utils.mjs b/src/utils.mjs
index 3c198fd..06de496 100644
--- a/src/utils.mjs
+++ b/src/utils.mjs
@@ -1,11 +1,12 @@
 import fs from 'node:fs';
+import { MS_PER_SECOND } from './constants.mjs';
 
 export function todayDateStr() {
   return new Date().toISOString().slice(0, 10);
 }
 
 export function nowUnix() {
-  return Math.floor(Date.now() / 1000);
+  return Math.floor(Date.now() / MS_PER_SECOND);
 }
 
 export function getIsoWeekStr(dateInput) {
diff --git a/task-logs/daily/2026-02-19T21-26-08Z__const-refactor-agent__completed.md b/task-logs/daily/2026-02-19T21-26-08Z__const-refactor-agent__completed.md
new file mode 100644
index 0000000..1aec8e7
--- /dev/null
+++ b/task-logs/daily/2026-02-19T21-26-08Z__const-refactor-agent__completed.md
@@ -0,0 +1,7 @@
+---
+agent: const-refactor-agent
+status: completed
+date: 2026-02-19
+timestamp: 2026-02-19T21-26-08Z
+---
+Refactored `1000` to `MS_PER_SECOND` in `src/constants.mjs` and usage sites.
diff --git a/test/scheduler-lock-failure-schema.contract.test.mjs b/test/scheduler-lock-failure-schema.contract.test.mjs
index 5a955d9..27b3868 100644
--- a/test/scheduler-lock-failure-schema.contract.test.mjs
+++ b/test/scheduler-lock-failure-schema.contract.test.mjs
@@ -96,6 +96,7 @@ async function setupFixture({ lockShellBody }) {
   await fs.copyFile(path.resolve('scripts/agent/scheduler-utils.mjs'), path.join(scriptsDir, 'scheduler-utils.mjs'));
   await fs.copyFile(path.resolve('scripts/agent/scheduler-lock.mjs'), path.join(scriptsDir, 'scheduler-lock.mjs'));
   await fs.copyFile(path.resolve('src/utils.mjs'), path.join(root, 'src', 'utils.mjs'));
+  await fs.copyFile(path.resolve('src/constants.mjs'), path.join(root, 'src', 'constants.mjs'));
   await fs.writeFile(path.join(scriptsDir, 'verify-run-artifacts.mjs'), '#!/usr/bin/env node\nprocess.exit(0);\n', 'utf8');
   await fs.writeFile(path.join(root, 'src', 'prompts', 'roster.json'), JSON.stringify({ daily: ['agent-a'] }, null, 2), 'utf8');
   await fs.writeFile(path.join(root, 'src', 'prompts', 'daily', 'agent-a.md'), '# agent-a\n', 'utf8');