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Claude Code Issues / #24976

Context Limit Reached error should auto-compact and queue user message instead of failing

Status Closed — not planned
Maintainer reply None cached
Workaround ✓ Mentioned in thread ↓
Activity 9 comments · opened Feb 11, 2026 · closed Mar 19, 2026

Description

When running long sessions with multiple parallel background agents (Task tool with run_in_background: true), sending a user message (especially with a screenshot attachment) while agents are still running throws a "Context Limit Reached" error instead of gracefully handling it.

This is on a Max plan — not a billing or rate limit issue. The model's context window is exhausted by accumulated agent results.

Expected Behavior

  1. User sends a message while agents are running
  2. System detects context is near/at limit
  3. System auto-compacts (summarizes prior messages)
  4. User's message is queued and processed after compaction
  5. Session continues seamlessly

Actual Behavior

  1. User sends a message while agents are running
  2. System throws "Context Limit Reached" error
  3. User cannot send any further messages
  4. /compact may also fail with the same error
  5. Only option is /clear — which loses all conversation history, agent results, and work in progress

Reproduction Steps

  1. Start a Claude Code session (Opus 4.6, Max plan)
  2. Launch 4-6 parallel background agents using the Task tool (e.g., SEO audit with 6 specialist subagents)
  3. While agents are running and returning results, send a new user message with a screenshot attachment
  4. Observe "Context Limit Reached" error

Root Cause Analysis

From investigating a crashed session (46MB JSONL transcript):

  • 274 user messages averaging 164KB each
  • 12 messages over 1MB, 39 over 100KB
  • 97.5% of context came from subagent results returned as user messages
  • The Task tool returns agent output as user-visible messages, which accumulate rapidly

Impact

  • Loss of work: Hours of multi-agent analysis lost when /clear is the only recovery
  • No recovery path: /compact fails with the same error, creating a dead-end state
  • Session state destroyed: TaskList, agent results, conversation history — all gone
  • Workaround burden on users: Must manually track when to /compact, which defeats the purpose of autonomous agent workflows

Suggested Solutions

Priority 1: Graceful degradation

When context limit is approaching:

  • Auto-trigger compaction before the hard limit is hit
  • Queue the user's pending message
  • Process the queued message after compaction succeeds

Priority 2: Pre-emptive compaction

  • Add a threshold (e.g., 80% of context window) that triggers automatic compaction
  • Or add a hook event like PreContextLimit that fires before the hard limit

Priority 3: Agent result management

  • Task tool results from background agents should not expand into full user messages
  • Consider: agent results as compressible system messages, or file-based result passing where agents write to disk and parent reads files

Current Workarounds

We've implemented partial mitigations via hooks and CLAUDE.md instructions:

  • SubagentStop hook reminds to /compact after agent work
  • PreCompact hook preserves critical context
  • All custom skills use file-based result passing (agents write to files, return only brief summaries)
  • But none of these prevent the hard crash when a user message arrives during heavy agent work

Environment

  • Plan: Claude Max (Opus 4.6)
  • Platform: macOS (Darwin 25.2.0)
  • Claude Code version: Latest as of Feb 2026
  • Model: claude-opus-4-6

View original on GitHub ↗

9 Comments

cosmicflow-space · 8 months ago

<img width="974" height="161" alt="Image" src="https://github.com/user-attachments/assets/1ab49493-3d56-4ef8-aeb2-b8d3864be5d2" />

github-actions[bot] · 8 months ago

Found 3 possible duplicate issues:

  1. https://github.com/anthropics/claude-code/issues/24341
  2. https://github.com/anthropics/claude-code/issues/23876
  3. https://github.com/anthropics/claude-code/issues/24220

This issue will be automatically closed as a duplicate in 3 days.

  • If your issue is a duplicate, please close it and 👍 the existing issue instead
  • To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

piwi3910 · 8 months ago

these are not duplicates, and or different issues.

Notum · 8 months ago

I can confirm this bug and currently working with claude code as an agenting development is just impossible.
Agents context window is shared between agents and main claude code context:

● Agent "Create Certifications migration+model" completed
⎿ Context limit reached · /compact or /clear to continue

● Agent "Add CRS org settings migration" completed
⎿ Context limit reached · /compact or /clear to continue

● Agent "Create CRS models and migration" completed
⎿ Context limit reached · /compact or /clear to continue

● Agent "Add Authorization access matrix" completed
⎿ Context limit reached · /compact or /clear to continue

● Agent "Auth routes, controller, sidebar" completed
⎿ Context limit reached · /compact or /clear to continue

This I got in same moment.

sarob · 8 months ago

i have been getting these msg in prompts over the past couple of days

  • Image base64 size (5.0 MB) exceeds API limit (5.0 MB). Please resize the image before sending.
  • prompt is too long
  • they are starting to impact my ability to work as I am regularly losing the conversation history. updating a plan markdown file is a workaround, but it is slowing me down.
  • when I try to report these bugs, the Fin AI Agent regularly hallucinates and tries to get me to use non-existing methods to report bugs, e.g. use /doctor or /bug or /debug within claude code.
  • when I ask for a human to help, I get a boilerplate we will email you and then nothing else. The communication stops. No more chat and no email that anything will happen.
  • I like the claude code tooling, but this is a poor experience with little hope of being repaired.
  • I am posting here as a last ditch option of getting any type of support
sarob · 7 months ago

Since losing conversation history was a recurring problem for me, I built a bash dashboard to track all Claude Code operational files (CLAUDE.md, MEMORY.md, conversation logs) across projects. It helps you see what Claude knows per project and clean up old session logs.

Zero dependencies, single script: https://github.com/sarob/claude-ops

github-actions[bot] · 6 months ago

Closing for now — inactive for too long. Please open a new issue if this is still relevant.

kimmeyh · 6 months ago

Please re-open as not confirmed to be fixed.
+1
Last occurred 03/21/2026 version 2.1.81
## Bug Description

Auto-compaction does not trigger before reaching the context limit when using
the 1M token context window. The session abruptly stops with "Context limit
reached" instead of auto-compacting to free up space.

## Environment

  • Claude Code on Windows 11
  • 64GB RAM
  • Model: claude-haiku-4-5-20251001 (also observed with other models)
  • Date: March 2026

## Steps to Reproduce

  1. Start a Claude Code session with a large codebase
  2. Perform extensive work (multiple file reads, edits, tool calls)
  3. Continue working until context fills up

## Expected Behavior

Auto-compaction should trigger at some threshold (e.g., 80-90% of context
limit) to free up context space and allow the session to continue without
interruption. This behavior previously worked when the context window was
smaller (pre-1M expansion).

## Actual Behavior

No auto-compaction occurs. The session hits the context limit and stops
abruptly. Observed on multiple occasions:

  • Session 1: Context limit reached at ~500,000-590,000 tokens (per status

bar) without auto-compaction

  • Session 2: Context limit reached at ~236,000 tokens without

auto-compaction

In both cases, manual /compact was required. Prior to the 1M token
context window expansion, auto-compaction would trigger automatically.

## Impact

  • Loss of work momentum during complex tasks
  • Risk of losing unsaved context/progress
  • Forces users to manually monitor context usage and run /compact

proactively

  • Particularly impactful during long collaborative sessions (e.g.,

interactive walkthroughs) where pausing to compact is disruptive

## Workaround

Manually run /compact before reaching the limit. However, this requires
constant monitoring of the context percentage in the status bar.

github-actions[bot] · 6 months ago

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.

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