Opus 4.6 (1M) loses track of its own actions within seconds in fresh context

Bug Description

In a fresh 1M context window (nearly empty, ~200-300 tokens of actual work done), Opus 4.6 lost track of actions it performed seconds earlier.

Steps to Reproduce

1. Open a fresh conversation with Opus 4.6 (1M context)
2. Model was given a task list (11 topics to create as HTML files)
3. Topics 1-2 were already completed from a previous session
4. Model ran mkdir to create an empty directory for topic 5
5. Immediately after, model ran ls on the parent directory
6. Model saw 5 directories (2 with files, 3 empty — including the one it just created)
7. Model concluded topics 1-4 were "already done" and wanted to skip to topic 5
8. It could not recall that it had just created that empty directory itself, seconds ago

Expected Behavior

The model should be able to track its own actions within the same context window, especially when the window is nearly empty.

Actual Behavior

• Model forgot its own mkdir command from seconds earlier
• Treated empty directories (that it created) as evidence of completed prior work
• Skipped 3 tasks that were not actually done
• This happened in a 1M context window with minimal content — not a context limit issue

Environment

• Model: Claude Opus 4.6 (1M context)
• Tool: Claude Code CLI
• Platform: macOS