Plan Mode updates are destructive: existing sections are rewritten/condensed instead of preserved

Summary

When using Plan Mode in the Codex desktop app, updating an existing plan causes previously defined sections to be rewritten, condensed, or degraded, even when the intent is to make a small, localized change.

This makes Plan Mode unsuitable for iterative workflows where a plan/spec is progressively refined over time.

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Expected Behavior

When asking Codex to update a plan:

• Existing sections that are not part of the requested change should be preserved verbatim
• Updates should behave like a patch / diff, not a full rewrite
• Previously “settled” parts of the plan should remain stable and intact

Example expectation:

“Update section X” → only section X changes, everything else remains unchanged

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Actual Behavior

• The entire plan is often regenerated
• Previously detailed sections become:
• shorter
• less precise
• missing important detail
• Structure and wording of unchanged sections may be altered
• Repeated updates lead to progressive degradation of the plan

This occurs even when:

• the requested change is small
• instructions explicitly say to preserve existing content

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Why This Is a Problem

Plan Mode appears to operate as a full rewrite system, not an incremental editing system.

This creates several issues:

1. Loss of Detail

• Carefully developed sections are compressed or simplified

1. Instability

• The same plan cannot be reliably refined over multiple iterations

1. Workflow Breakage

• Users must constantly re-inject or restate prior decisions

1. Not Suitable for Spec Development

• Makes it difficult to build production-grade specs that require precision and accumulation of detail

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Reproduction Steps

1. Create a detailed multi-section plan in Plan Mode
2. Ensure multiple sections contain non-trivial detail
3. Ask Codex to:

• update a specific section
• or make a targeted change

1. Observe:

• other sections are rewritten or condensed
• wording and structure change outside the requested scope

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Key Distinction

This is not just a context window or memory issue.

This is a Plan Mode behavior issue:

• The system appears to regenerate the entire plan
• There is no concept of:
• locked sections
• stable sections
• partial updates

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Suggested Improvements

1. Non-destructive Updates

• Support patch-style updates instead of full regeneration

1. Section Stability

• Allow sections to remain unchanged unless explicitly modified

1. “Locked” Sections

• Ability to mark parts of a plan as immutable

1. Structured Plan Editing

• Treat plans as structured documents, not freeform text rewrites

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Impact

This significantly limits Plan Mode for:

• spec writing
• system design
• multi-step planning workflows

Users attempting to build detailed plans experience:

• repeated loss of work
• increased friction
• unreliable iteration

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Closing

Plan Mode is powerful, but currently behaves like a stateless rewrite system rather than a stateful planning tool.

Supporting non-destructive updates would make it significantly more useful for real-world development workflows.