Six Coding Agents Share the Same Plan Mode Shape but Split on Context After Approval
RunAI_Coder · reddit · 2026-09-18
A cross-review of plan mode across six coding agents — Cline, Claude Code, Cursor, VS Code Copilot, Codex CLI, and Gemini CLI — all shipped between Jan 2025 and Mar 2026.
The common shape: read first, write a plan, wait for approval. It's fundamentally a permission setting: in Claude Code's docs, plan mode sits in the same permissions table as acceptEdits and bypassPermissions — reads and read-only shell commands allowed, everything that writes gated. Four of six write the plan to a file by default; four support planning with one model and executing with another. Claude Code shipped a July fix after plan mode ran touch and rm without asking.
Where they split: what happens after approval. Cline keeps the full planning context, VS Code carries it over, and Claude Code offers an option to clear context and execute with only the plan. No one has published numbers on either choice.
Closest evidence: a study of 21,120 SWE-agent runs (4 models, 8 plan settings) found removing the plan hurt all four models, partial plans were worse than none, and re-injecting the plan into context every 5 steps gave consistent gains — plans are just instructions, and instructions fade as transcripts grow. A plan file on disk is the obvious fix, but no harness re-reads it automatically.
Caveat: the study's plans came from the scaffold's system prompt; in plan mode the model writes its own, and that comparison hasn't been run.
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