diff --git a/openspec/changes/fix-cli-local-date-semantics/.openspec.yaml b/openspec/changes/fix-cli-local-date-semantics/.openspec.yaml
new file mode 100644
index 0000000000..4f63482c1e
--- /dev/null
+++ b/openspec/changes/fix-cli-local-date-semantics/.openspec.yaml
@@ -0,0 +1,2 @@
+schema: spec-driven
+created: 2026-07-15
diff --git a/openspec/changes/fix-cli-local-date-semantics/design.md b/openspec/changes/fix-cli-local-date-semantics/design.md
new file mode 100644
index 0000000000..c8ee25e62c
--- /dev/null
+++ b/openspec/changes/fix-cli-local-date-semantics/design.md
@@ -0,0 +1,52 @@
+## Context
+
+The CLI currently creates two user-visible date-only values by truncating `Date#toISOString()`: archive directory prefixes and the `created` field in newly scaffolded `.openspec.yaml` files. ISO serialization is UTC, so either value can disagree with the calendar date in the effective local time zone of the Node.js process running the CLI.
+
+The repository supports Node.js 20.19+ on Windows, macOS, and Linux. The selected contract is the calendar date in the executing Node.js process's effective local time zone, rather than a project-wide or UTC time zone. "Effective local time zone" means the time zone used by Node.js local `Date` accessors, normally derived from the host environment and any runtime-supported process time-zone configuration.
+
+## Goals / Non-Goals
+
+**Goals:**
+
+- Produce date-only archive prefixes and new-change metadata from the executing CLI process's effective local calendar date.
+- Keep the date representation stable as zero-padded `YYYY-MM-DD` on every supported platform.
+- Cover a UTC/local-calendar boundary with deterministic tests.
+
+**Non-Goals:**
+
+- Rename or migrate existing archive directories or existing change metadata.
+- Add a project time-zone setting, CLI flag, or user-selectable time zone.
+- Change full UTC timestamps used for logs, JSON timestamps, feedback metadata, or backup identifiers.
+- Alter agent-generated date prefixes in OPSX archive workflows, which do not derive their dates through `Date#toISOString()`.
+
+## Decisions
+
+### Use a shared local calendar-date formatter
+
+Introduce one small shared formatter for date-only values. It will derive year, month, and day with local `Date` accessors and zero-pad the numeric parts into `YYYY-MM-DD`. It will accept a `Date` value (defaulting to the current time) so callers share the same behavior and tests can provide a fixed instant.
+
+Both archive naming and change creation will call this formatter. This prevents the two date-only concepts from diverging again while keeping the existing archive and metadata APIs unchanged.
+
+`toISOString().split('T')[0]` is not suitable because it deliberately selects the UTC calendar date. Locale-formatted strings are also unsuitable as a storage and path contract because their separators and ordering are locale-dependent.
+
+### Bind the rule to the executing CLI process's effective local time zone
+
+The formatter will use the local time zone effective for the Node.js process. This matches the user-visible meaning of "today" for an interactive CLI session and gives scripts deterministic behavior when the process time zone is configured. Processes in different time zones may produce different dates for the same instant near a boundary; that is intentional under the selected contract.
+
+### Test the boundary through the process time zone
+
+Tests will temporarily set the Node process time zone to `Asia/Shanghai` and use a fixed instant such as `2026-07-14T16:30:00.000Z`. At that instant the local date is `2026-07-15` while the UTC date is `2026-07-14`, so the test fails if UTC truncation returns. The test setup will restore time and environment state after each case.
+
+## Risks / Trade-offs
+
+- [Different processes can choose different dates at the same instant] → This is the explicit effective-local-time-zone contract and is covered by the affected behavior.
+- [Date formatting is accidentally made locale-sensitive] → Use numeric local `Date` parts rather than locale display formatting.
+- [Existing historical names retain UTC-derived dates] → Apply the new rule prospectively and leave existing directories and metadata untouched.
+
+## Migration Plan
+
+No data migration is required. New archives and newly created changes use the local-date rule after release; existing archives and metadata remain valid as-is.
+
+## Open Questions
+
+None.
diff --git a/openspec/changes/fix-cli-local-date-semantics/proposal.md b/openspec/changes/fix-cli-local-date-semantics/proposal.md
new file mode 100644
index 0000000000..44eee1ffa6
--- /dev/null
+++ b/openspec/changes/fix-cli-local-date-semantics/proposal.md
@@ -0,0 +1,27 @@
+## Why
+
+Two CLI code paths currently derive date-only values by truncating a UTC ISO timestamp: archive directory prefixes and the `created` field in newly scaffolded change metadata. Near a local midnight boundary, these values can resolve to the previous or next calendar date instead of the date in the CLI process's effective local time zone.
+
+## What Changes
+
+- Define CLI-generated date-only values as the calendar date in the effective local time zone of the Node.js process executing the CLI, formatted as `YYYY-MM-DD`.
+- Generate CLI archive directory names from that local date.
+- Record the same local date in the `created` field of newly created change metadata.
+- Add regression coverage for a non-UTC local-date boundary.
+
+## Capabilities
+
+### New Capabilities
+
+None.
+
+### Modified Capabilities
+
+- `cli-archive`: archive target names use the CLI process's effective local calendar date.
+- `change-creation`: newly created change metadata records the CLI process's effective local calendar date.
+
+## Impact
+
+- Affected code: archive naming, change-creation metadata, and a shared date-only formatter.
+- Affected tests: archive and change-creation coverage.
+- Existing archive directories remain unchanged; the rule applies to newly generated names and metadata only.
diff --git a/openspec/changes/fix-cli-local-date-semantics/specs/change-creation/spec.md b/openspec/changes/fix-cli-local-date-semantics/specs/change-creation/spec.md
new file mode 100644
index 0000000000..f606d30e9c
--- /dev/null
+++ b/openspec/changes/fix-cli-local-date-semantics/specs/change-creation/spec.md
@@ -0,0 +1,12 @@
+## ADDED Requirements
+
+### Requirement: Local Creation Date Metadata
+
+The system SHALL record the `created` value in metadata for a newly created change as the `YYYY-MM-DD` calendar date in the effective local time zone of the Node.js process executing the CLI.
+
+#### Scenario: Create change across a UTC date boundary
+
+- **GIVEN** the CLI process's effective local time zone is `Asia/Shanghai`
+- **AND** the current instant is `2026-07-14T16:30:00.000Z`
+- **WHEN** the user creates a change
+- **THEN** the new change's `.openspec.yaml` contains `created: 2026-07-15`
diff --git a/openspec/changes/fix-cli-local-date-semantics/specs/cli-archive/spec.md b/openspec/changes/fix-cli-local-date-semantics/specs/cli-archive/spec.md
new file mode 100644
index 0000000000..aa114e7146
--- /dev/null
+++ b/openspec/changes/fix-cli-local-date-semantics/specs/cli-archive/spec.md
@@ -0,0 +1,17 @@
+## ADDED Requirements
+
+### Requirement: Local Archive Date
+
+The archive command SHALL derive the `YYYY-MM-DD` prefix of a new archive target from the calendar date in the effective local time zone of the Node.js process executing the CLI.
+
+#### Scenario: Archive crosses a UTC date boundary
+
+- **GIVEN** the CLI process's effective local time zone is `Asia/Shanghai`
+- **AND** the current instant is `2026-07-14T16:30:00.000Z`
+- **WHEN** the user archives a change named `add-auth`
+- **THEN** the target archive name begins with `2026-07-15-add-auth`
+
+#### Scenario: Non-interactive archive uses the local date
+
+- **WHEN** an automation invokes `openspec archive <change-name> --yes`
+- **THEN** the target archive name uses the CLI process's effective local calendar date
diff --git a/openspec/changes/fix-cli-local-date-semantics/tasks.md b/openspec/changes/fix-cli-local-date-semantics/tasks.md
new file mode 100644
index 0000000000..9bb6c7067e
--- /dev/null
+++ b/openspec/changes/fix-cli-local-date-semantics/tasks.md
@@ -0,0 +1,13 @@
+## 1. Local date behavior
+
+- [x] 1.1 Add a shared formatter that returns the calendar date in the executing Node.js process's effective local time zone as `YYYY-MM-DD`.
+- [x] 1.2 Use the shared formatter for native archive target names.
+- [x] 1.3 Use the shared formatter when writing `created` metadata for a new change.
+
+## 2. Regression coverage and validation
+
+- [x] 2.1 Add archive and change-creation tests for a fixed `Asia/Shanghai` UTC-boundary instant, restoring clock and environment state afterward.
+- [x] 2.2 Update affected archive test expectations to use the effective-local-date contract.
+- [x] 2.3 Add archive and change-creation tests for a non-boundary instant where UTC and local calendar dates match.
+- [x] 2.4 Run focused archive and change-creation tests on the supported cross-platform test suite.
+- [x] 2.5 Run the full build and OpenSpec validation for the change.
diff --git a/src/core/archive.ts b/src/core/archive.ts
index df37695b82..7587959a7e 100644
--- a/src/core/archive.ts
+++ b/src/core/archive.ts
@@ -1,5 +1,6 @@
 import { promises as fs } from 'fs';
 import path from 'path';
+import { formatLocalDate } from '../utils/date.js';
 import { getTaskProgressForChange, formatTaskStatus } from '../utils/task-progress.js';
 import { Validator } from './validation/validator.js';
 import chalk from 'chalk';
@@ -482,7 +483,7 @@ export class ArchiveCommand {
     }
 
     // Create archive directory with date prefix
-    const archiveName = `${this.getArchiveDate()}-${changeName}`;
+    const archiveName = `${formatLocalDate()}-${changeName}`;
     const archivePath = path.join(archiveDir, archiveName);
 
     // Check if archive already exists
@@ -557,9 +558,4 @@ export class ArchiveCommand {
       return null;
     }
   }
-
-  private getArchiveDate(): string {
-    // Returns date in YYYY-MM-DD format
-    return new Date().toISOString().split('T')[0];
-  }
 }
diff --git a/src/utils/change-utils.ts b/src/utils/change-utils.ts
index c47a4a3efe..71bdd6e1ad 100644
--- a/src/utils/change-utils.ts
+++ b/src/utils/change-utils.ts
@@ -1,6 +1,7 @@
 import path from 'path';
 import { FileSystemUtils } from './file-system.js';
 import { writeChangeMetadata, validateSchemaName } from './change-metadata.js';
+import { formatLocalDate } from './date.js';
 import { readProjectConfig } from '../core/project-config.js';
 import type { ChangeMetadata } from '../core/change-metadata/index.js';
 
@@ -179,10 +180,9 @@ export async function createChange(
   }
 
   // Write metadata file with schema and creation date
-  const today = new Date().toISOString().split('T')[0];
   writeChangeMetadata(changeDir, {
     schema: schemaName,
-    created: today,
+    created: formatLocalDate(),
     ...options.metadata,
   }, projectRoot);
 
diff --git a/src/utils/date.ts b/src/utils/date.ts
new file mode 100644
index 0000000000..e76a54c1bc
--- /dev/null
+++ b/src/utils/date.ts
@@ -0,0 +1,13 @@
+/**
+ * Formats a date using the effective local time zone of the Node.js process.
+ *
+ * The result is locale-independent and suitable for date-only metadata and
+ * path prefixes.
+ */
+export function formatLocalDate(date: Date = new Date()): string {
+  const year = date.getFullYear();
+  const month = String(date.getMonth() + 1).padStart(2, '0');
+  const day = String(date.getDate()).padStart(2, '0');
+
+  return `${year}-${month}-${day}`;
+}
diff --git a/test/core/archive.test.ts b/test/core/archive.test.ts
index 9a7624ef54..5d11a2566b 100644
--- a/test/core/archive.test.ts
+++ b/test/core/archive.test.ts
@@ -1,6 +1,7 @@
 import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
 import { ArchiveCommand } from '../../src/core/archive.js';
 import { Validator } from '../../src/core/validation/validator.js';
+import { formatLocalDate } from '../../src/utils/date.js';
 import { promises as fs } from 'fs';
 import path from 'path';
 import os from 'os';
@@ -17,6 +18,7 @@ describe('ArchiveCommand', () => {
   const originalConsoleLog = console.log;
   const originalExitCode = process.exitCode;
   const originalXdgDataHome = process.env.XDG_DATA_HOME;
+  const originalTimeZone = process.env.TZ;
 
   beforeEach(async () => {
     // Create temp directory
@@ -47,6 +49,8 @@ describe('ArchiveCommand', () => {
   });
 
   afterEach(async () => {
+    vi.useRealTimers();
+
     // Restore console.log
     console.log = originalConsoleLog;
 
@@ -59,6 +63,12 @@ describe('ArchiveCommand', () => {
       process.env.XDG_DATA_HOME = originalXdgDataHome;
     }
 
+    if (originalTimeZone === undefined) {
+      delete process.env.TZ;
+    } else {
+      process.env.TZ = originalTimeZone;
+    }
+
     // Clear mocks
     vi.clearAllMocks();
 
@@ -95,6 +105,38 @@ describe('ArchiveCommand', () => {
       await expect(fs.access(changeDir)).rejects.toThrow();
     });
 
+    it('should use the process local date across a UTC date boundary', async () => {
+      process.env.TZ = 'Asia/Shanghai';
+      vi.useFakeTimers();
+      vi.setSystemTime(new Date('2026-07-14T16:30:00.000Z'));
+
+      const changeName = 'local-date-feature';
+      const changeDir = path.join(tempDir, 'openspec', 'changes', changeName);
+      await fs.mkdir(changeDir, { recursive: true });
+      await fs.writeFile(path.join(changeDir, 'tasks.md'), '- [x] Task 1\n');
+
+      await archiveCommand.execute(changeName, { yes: true, noValidate: true, skipSpecs: true });
+
+      const archiveDir = path.join(tempDir, 'openspec', 'changes', 'archive');
+      await expect(fs.readdir(archiveDir)).resolves.toEqual([`2026-07-15-${changeName}`]);
+    });
+
+    it('should preserve the date when UTC and local calendar dates match', async () => {
+      process.env.TZ = 'Asia/Shanghai';
+      vi.useFakeTimers();
+      vi.setSystemTime(new Date('2026-01-05T04:30:00.000Z'));
+
+      const changeName = 'same-date-feature';
+      const changeDir = path.join(tempDir, 'openspec', 'changes', changeName);
+      await fs.mkdir(changeDir, { recursive: true });
+      await fs.writeFile(path.join(changeDir, 'tasks.md'), '- [x] Task 1\n');
+
+      await archiveCommand.execute(changeName, { yes: true, noValidate: true, skipSpecs: true });
+
+      const archiveDir = path.join(tempDir, 'openspec', 'changes', 'archive');
+      await expect(fs.readdir(archiveDir)).resolves.toEqual([`2026-01-05-${changeName}`]);
+    });
+
     it('should warn about incomplete tasks', async () => {
       const changeName = 'incomplete-feature';
       const changeDir = path.join(tempDir, 'openspec', 'changes', changeName);
@@ -441,7 +483,7 @@ New feature description.
       await fs.mkdir(changeDir, { recursive: true });
       
       // Create existing archive with same date
-      const date = new Date().toISOString().split('T')[0];
+      const date = formatLocalDate();
       const archivePath = path.join(tempDir, 'openspec', 'changes', 'archive', `${date}-${changeName}`);
       await fs.mkdir(archivePath, { recursive: true });
       
diff --git a/test/utils/change-utils.test.ts b/test/utils/change-utils.test.ts
index 090b21b24f..587a7b75f6 100644
--- a/test/utils/change-utils.test.ts
+++ b/test/utils/change-utils.test.ts
@@ -1,4 +1,4 @@
-import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
 import { promises as fs } from 'fs';
 import path from 'path';
 import os from 'os';
@@ -110,6 +110,7 @@ describe('validateChangeName', () => {
 
 describe('createChange', () => {
   let testDir: string;
+  const originalTimeZone = process.env.TZ;
 
   beforeEach(async () => {
     testDir = path.join(os.tmpdir(), `openspec-test-${randomUUID()}`);
@@ -117,6 +118,12 @@ describe('createChange', () => {
   });
 
   afterEach(async () => {
+    vi.useRealTimers();
+    if (originalTimeZone === undefined) {
+      delete process.env.TZ;
+    } else {
+      process.env.TZ = originalTimeZone;
+    }
     await fs.rm(testDir, { recursive: true, force: true });
   });
 
@@ -138,6 +145,30 @@ describe('createChange', () => {
       expect(content).toMatch(/created: \d{4}-\d{2}-\d{2}/);
     });
 
+    it('should use the process local date across a UTC date boundary', async () => {
+      process.env.TZ = 'Asia/Shanghai';
+      vi.useFakeTimers();
+      vi.setSystemTime(new Date('2026-07-14T16:30:00.000Z'));
+
+      await createChange(testDir, 'local-date-change');
+
+      const metaPath = path.join(testDir, 'openspec', 'changes', 'local-date-change', '.openspec.yaml');
+      const content = await fs.readFile(metaPath, 'utf-8');
+      expect(content).toContain('created: 2026-07-15');
+    });
+
+    it('should preserve the date when UTC and local calendar dates match', async () => {
+      process.env.TZ = 'Asia/Shanghai';
+      vi.useFakeTimers();
+      vi.setSystemTime(new Date('2026-01-05T04:30:00.000Z'));
+
+      await createChange(testDir, 'same-date-change');
+
+      const metaPath = path.join(testDir, 'openspec', 'changes', 'same-date-change', '.openspec.yaml');
+      const content = await fs.readFile(metaPath, 'utf-8');
+      expect(content).toContain('created: 2026-01-05');
+    });
+
     it('should create .openspec.yaml with custom schema', async () => {
       await createChange(testDir, 'add-auth', { schema: 'spec-driven' });