Opus 4.6 regression: ignores established session patterns after context restore

Environment

• Claude Code CLI on Windows 11
• Model: Claude Opus 4.6
• Date: 2026-04-19

Description

After a context restore (session continuation from a previous conversation that hit context limits), Opus 4.6 exhibited multiple regressions compared to behavior in the same session before the context break:

1. Regenerated maps with matplotlib instead of using existing ArcGIS exports. User asked to recreate Figure 13 with WGS 84 coordinates. ArcGIS-exported PNGs already existed at maps/exports/CCI.png and maps/exports/MSI.png (exported same day). Instead of compositing those, the model re-rendered maps from raw rasters using matplotlib — producing inferior output without proper cartographic elements (scale bars, north arrows, graticules, district boundaries). User had to explicitly point out the exports existed.

1. Unnecessary version increment on PermissionError. When the output DOCX was locked (open in Word), prior sessions would wait for the user to close it and retry. Instead, the model immediately incremented the filename from v5 to v6. When user pointed this out, the model had to revert.

1. Context restore confusion. At the start of the restored session, the model called ExitPlanMode and ToolSearch before addressing the user, causing the user to think context was being compacted again.

Expected behavior

• Check maps/exports/ for existing ArcGIS-exported maps before generating matplotlib replacements
• On PermissionError, ask the user to close the file and retry with the same filename
• After context restore, resume work smoothly without unnecessary tool calls that confuse the user

User impact

Multiple round-trips wasted correcting avoidable mistakes. User describes this as "total stupidity" and feels the model was "nerfed" compared to prior sessions.