Skip to content

Plan→Compact→Re-Plan infinite loop in agency copilot (auto-compaction causes self-perpetuating planning) #3155

@Akhi-microsoft

Description

@Akhi-microsoft

Repro: Started a coding task with agency copilot. After auto-compaction fired, the agent re-read the compaction summary and started re-planning instead of executing. This repeated through 217 plan→compact→re-plan cycles before I killed the session.

Root cause (hypothesis): Compaction summarizes "we planned X, Y, Z" into the new context. The agent reads the summary and treats the plan as a fresh prompt to plan against, instead of as decided work to execute. The plan becomes self-perpetuating. With no execution-bias instruction surviving compaction, the loop is structural — not prompt-specific.

Expected behavior: After compaction, the agent resumes from the next concrete file edit. Plans already produced are treated as decided, not as a fresh prompt to re-plan against.

Actual behavior: Agent re-summarizes its own plan, validates it, and repeats. No file edits across hundreds of turns.

Impact:

  • Burned through hours of compute and Copilot quota
  • Zero code written despite hundreds of turns
  • Severe trust hit for autonomous/long-running workflows
  • Likely under-reported — users blame themselves before blaming the tool

Asks (priority order):

  1. Compaction summarizer: label plans as DECIDED — do not re-plan and surface next concrete action as the primary continuation signal.
  2. Inject a default post-compact rule: Resume from the next file edit. Do not re-validate the plan. (Reference: https://github.com/Dicklesworthstone/post_compact_reminder)
  3. Add an --mode execute session flag that biases hard against planning preambles.
  4. Loop detector: N consecutive turns with zero file edits → halt and prompt user (suggested default N=3).
  5. Improve /compact defaults: drop planning history, keep only files modified, current error state, and next concrete action.
  6. Add telemetry signal for "planning loop suspected" to quantify real-world frequency.

Current workarounds (shouldn't be required of every user):

  • AGENTS.md with explicit "no re-plan after compact" rule
  • Post-compact reminder hook (manual third-party install)
  • Manual /compact at ~60% with explicit preservation instructions
  • HANDOFF.md as ground-truth state file

Happy to share session logs and jump on a triage call to walk through the repro.

— Akhi Shukla, Senior PM, IC3 / UED (Prague)
Manager: Bryan Castro | Skip: Nils Dussart

Metadata

Metadata

Assignees

No one assigned

    Labels

    area:agentsSub-agents, fleet, autopilot, plan mode, background agents, and custom agentsarea:context-memoryContext window, memory, compaction, checkpoints, and instruction loading

    Type

    No fields configured for Bug.

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions