[BUG] v1.0.45 --resume bug

Summary

Claude CLI v1.0.45 ignores the --resume flag and creates new sessions instead of resuming existing ones, causing loss of conversation history.

Environment

• Claude CLI Version: 1.0.45 (Claude Code)
• Platform: macOS
• Output Format: stream-json

Bug Description

When passing the --resume <session-id> flag to Claude CLI, it ignores the session ID and creates a new session instead of resuming the existing one. This results in:

• Loss of conversation context
• Inability to continue previous conversations
• New session IDs generated for every command
• Breaking session-based applications

Steps to Reproduce

1. Start a Claude session and note the session ID returned
2. Send a follow-up message attempting to resume that session:

``bash
claude --print "follow-up message" --resume <previous-session-id> --output-format stream-json --verbose
``

1. Observe the response - Claude returns a completely new session ID instead of resuming

Expected Behavior

When using --resume <session-id>, Claude should:

• Load the existing session context
• Continue the conversation with full history
• Return the same session ID in the response
• Maintain conversation continuity

Actual Behavior

Claude CLI:

• Ignores the provided session ID
• Creates a brand new session
• Returns a different session ID
• Loses all conversation context

Reproducible Test Cases

Test Case 1: Simple Resume Attempt

Command sent:

claude --print "Hello, please help me with a task" --resume 12345678-abcd-efgh-ijkl-123456789012 --output-format stream-json --verbose

Response received:

{
  "type": "system",
  "subtype": "init",
  "session_id": "87654321-wxyz-uvwx-stuv-987654321098",
  "model": "claude-opus-4-20250514"
}

Note: Requested resume of session 12345678-abcd-efgh-ijkl-123456789012 but got new session 87654321-wxyz-uvwx-stuv-987654321098

Test Case 2: Multiple Resume Attempts - Same Session

First attempt:

claude --print "First message" --resume aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee --output-format stream-json

Returns: "session_id": "11111111-2222-3333-4444-555555555555"

Second attempt (same resume ID):

claude --print "Second message" --resume aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee --output-format stream-json

Returns: "session_id": "66666666-7777-8888-9999-000000000000"

Both attempts create new sessions instead of resuming the requested one.

Test Case 3: Resume After Session Exists

1. Initial session created normally (no resume flag)
2. Session ID confirmed to exist in Claude's session storage
3. Attempt to resume:

claude --print "Continue our previous discussion" --resume <existing-session-id> --output-format stream-json

1. Result: New session created, previous context lost

Pattern Analysis

• The bug occurs 100% of the time
• Affects all session IDs (valid UUID format)
• Independent of message content
• Independent of tool configuration
• Occurs in both interactive and non-interactive modes

Impact

This bug makes it impossible to:

• Build stateful applications using Claude CLI
• Maintain conversation context across multiple API calls
• Implement multi-turn conversations programmatically
• Create chat interfaces that preserve history
• Resume interrupted sessions

Expected Response Format

When resume works correctly, the response should maintain the session:

{
  "type": "system",
  "subtype": "init",
  "session_id": "12345678-abcd-efgh-ijkl-123456789012",  // Same as --resume parameter
  "model": "claude-opus-4-20250514"
}

Severity

High - This completely breaks session management functionality, making it impossible to build applications that require conversation continuity.