Context window changes from 1M to 258K mid-thread

Open 💬 2 comments Opened Jun 19, 2026 by imxika

💡 Likely answer: A maintainer (github-actions[bot], contributor) responded on this thread — see the highlighted reply below.

What version of Codex CLI is running?

codex-cli 0.141.0

What subscription do you have?

pro lite

Which model were you using?

gpt-5.5 high

What platform is your computer?

Darwin 25.5.0 arm64 arm

What terminal emulator and version are you using (if applicable)?

tmux

Codex doctor report

admin@AIBot-01 ~ % codex doctor --json
{
  "schemaVersion": 1,
  "generatedAt": "1781841606s since unix epoch",
  "overallStatus": "ok",
  "codexVersion": "0.141.0",
  "checks": {
    "app_server.status": {
      "id": "app_server.status",
      "category": "app-server",
      "status": "ok",
      "summary": "background server is not running",
      "details": {
        "control socket": "/Users/admin/.codex/app-server-control/app-server-control.sock",
        "daemon state dir": "/Users/admin/.codex/app-server-daemon",
        "mode": "ephemeral",
        "pid file": "/Users/admin/.codex/app-server-daemon/app-server.pid (missing)",
        "settings": "/Users/admin/.codex/app-server-daemon/settings.json (missing)",
        "status": "not running",
        "update-loop pid file": "/Users/admin/.codex/app-server-daemon/app-server-updater.pid (missing)"
      },
      "remediation": null,
      "durationMs": 0
    },
    "auth.credentials": {
      "id": "auth.credentials",
      "category": "auth",
      "status": "ok",
      "summary": "auth is configured",
      "details": {
        "auth file": "/Users/admin/.codex/auth.json",
        "auth storage mode": "File",
        "stored API key": "false",
        "stored ChatGPT tokens": "true",
        "stored agent identity": "false",
        "stored auth mode": "chatgpt"
      },
      "remediation": null,
      "durationMs": 0
    },
    "config.load": {
      "id": "config.load",
      "category": "config",
      "status": "ok",
      "summary": "config loaded",
      "details": {
        "CODEX_HOME": "/Users/admin/.codex",
        "config.toml": "/Users/admin/.codex/config.toml",
        "config.toml parse": "ok",
        "cwd": "/Users/admin",
        "enabled feature flags": "shell_tool, unified_exec, shell_snapshot, terminal_resize_reflow, sqlite, hooks, enable_request_compression, multi_agent, apps, tool_suggest, plugins, in_app_browser, browser_use, browser_use_external, computer_use, plugin_sharing, image_generation, skill_mcp_dependency_install, mentions_v2, steer, guardian_approval, goals, collaboration_modes, tool_call_mcp_elicitation, personality, fast_mode, tui_app_server, remote_compaction_v2, workspace_dependencies",
        "feature flag overrides": "none",
        "feature flags enabled": "29",
        "log dir": "/Users/admin/.codex/log",
        "mcp servers": "0",
        "model": "gpt-5.5",
        "model provider": "openai",
        "sqlite home": "/Users/admin/.codex"
      },
      "remediation": null,
      "durationMs": 0
    },
    "git.environment": {
      "id": "git.environment",
      "category": "git",
      "status": "ok",
      "summary": "git version 2.50.1 (Apple Git-155)",
      "details": {
        "PATH git #1": "/usr/bin/git",
        "PATH git entries": "1",
        "git build options": "git version 2.50.1 (Apple Git-155); cpu: arm64; no commit associated with this build; sizeof-long: 8; sizeof-size_t: 8; shell-path: /bin/sh; feature: fsmonitor--daemon; libcurl: 8.7.1; zlib: 1.2.12; SHA-1: SHA1_DC; SHA-256: SHA256_BLK",
        "git exec path": "/Library/Developer/CommandLineTools/usr/libexec/git-core",
        "git version": "git version 2.50.1 (Apple Git-155)",
        "repo detected": "false",
        "selected git": "/usr/bin/git"
      },
      "remediation": null,
      "durationMs": 124
    },
    "installation": {
      "id": "installation",
      "category": "install",
      "status": "ok",
      "summary": "installation looks consistent",
      "details": {
        "PATH codex #1": "/Users/admin/.nvm/versions/node/v22.22.0/bin/codex",
        "PATH codex #2": "/opt/homebrew/bin/codex",
        "PATH codex entries": "2",
        "current executable": "/Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin/bin/codex",
        "install context": "npm (package /Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin, bin /Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin/bin, resources /Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin/codex-resources, path /Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin/codex-path)",
        "managed by bun": "false",
        "managed by npm": "true",
        "managed package root": "/Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex",
        "npm update target": "/Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex"
      },
      "remediation": null,
      "durationMs": 121
    },
    "mcp.config": {
      "id": "mcp.config",
      "category": "mcp",
      "status": "ok",
      "summary": "no MCP servers configured",
      "details": {},
      "remediation": null,
      "durationMs": 0
    },
    "network.env": {
      "id": "network.env",
      "category": "network",
      "status": "ok",
      "summary": "network-related environment looks readable",
      "details": {
        "proxy env vars": "none"
      },
      "remediation": null,
      "durationMs": 0
    },
    "network.provider_reachability": {
      "id": "network.provider_reachability",
      "category": "reachability",
      "status": "ok",
      "summary": "active provider endpoints are reachable over HTTP",
      "details": {
        "ChatGPT base URL": "https://chatgpt.com/backend-api/ reachable (HTTP 403)",
        "reachability mode": "ChatGPT auth"
      },
      "remediation": null,
      "durationMs": 131
    },
    "network.websocket_reachability": {
      "id": "network.websocket_reachability",
      "category": "websocket",
      "status": "ok",
      "summary": "Responses WebSocket handshake succeeded",
      "details": {
        "DNS": "2 IPv4, 2 IPv6, first IPv4",
        "auth mode": "chatgpt",
        "connect timeout": "15000 ms",
        "endpoint": "wss://chatgpt.com/backend-api/<redacted>",
        "handshake result": "HTTP 101 Switching Protocols",
        "model provider": "openai",
        "models etag present": "true",
        "provider name": "OpenAI",
        "proxy env vars": "none",
        "reasoning header": "false",
        "server model present": "false",
        "supports websockets": "true",
        "wire API": "responses"
      },
      "remediation": null,
      "durationMs": 576
    },
    "runtime.provenance": {
      "id": "runtime.provenance",
      "category": "runtime",
      "status": "ok",
      "summary": "running npm on macos-aarch64",
      "details": {
        "commit": "unknown",
        "current executable": "/Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin/bin/codex",
        "install method": "npm (package /Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin, bin /Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin/bin, resources /Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin/codex-resources, path /Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin/codex-path)",
        "platform": "macos-aarch64",
        "version": "0.141.0"
      },
      "remediation": null,
      "durationMs": 0
    },
    "runtime.search": {
      "id": "runtime.search",
      "category": "search",
      "status": "ok",
      "summary": "search is OK (bundled)",
      "details": {
        "search command": "/Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex/node_modules/@openai/codex-darwin-arm64/vendor/aarch64-apple-darwin/codex-path/rg",
        "search command readiness": "file exists",
        "search provider": "bundled"
      },
      "remediation": null,
      "durationMs": 0
    },
    "sandbox.helpers": {
      "id": "sandbox.helpers",
      "category": "sandbox",
      "status": "ok",
      "summary": "sandbox configuration is readable",
      "details": {
        "approval policy": "OnRequest",
        "codex-linux-sandbox helper": "none",
        "execve wrapper helper": "/Users/admin/.codex/tmp/arg0/codex-arg00cM73W/codex-execve-wrapper",
        "filesystem sandbox": "restricted",
        "network sandbox": "restricted"
      },
      "remediation": null,
      "durationMs": 0
    },
    "state.paths": {
      "id": "state.paths",
      "category": "state",
      "status": "ok",
      "summary": "state paths and databases are inspectable",
      "details": {
        "CODEX_HOME": "/Users/admin/.codex (dir)",
        "active rollout files": "39 files, 58888199 total bytes, 1509953 average bytes",
        "archived rollout files": "0 files, 0 total bytes, 0 average bytes",
        "goals DB": "/Users/admin/.codex/goals_1.sqlite (file)",
        "goals DB integrity": "ok",
        "log DB": "/Users/admin/.codex/logs_2.sqlite (file)",
        "log DB integrity": "ok",
        "log dir": "/Users/admin/.codex/log (dir)",
        "memories DB": "/Users/admin/.codex/memories_1.sqlite (file)",
        "memories DB integrity": "ok",
        "sqlite home": "/Users/admin/.codex (dir)",
        "state DB": "/Users/admin/.codex/state_5.sqlite (file)",
        "state DB integrity": "ok"
      },
      "remediation": null,
      "durationMs": 125
    },
    "state.rollout_db_parity": {
      "id": "state.rollout_db_parity",
      "category": "threads",
      "status": "ok",
      "summary": "rollout files and state DB thread inventory agree",
      "details": {
        "default model provider": "openai",
        "rollout DB active files": "39",
        "rollout DB active rows": "39",
        "rollout DB archive mismatches": "0",
        "rollout DB archived files": "0",
        "rollout DB archived rows": "0",
        "rollout DB duplicate DB paths": "0",
        "rollout DB duplicate rollout thread ids": "0",
        "rollout DB malformed file names": "0",
        "rollout DB missing active rows": "0",
        "rollout DB missing archived rows": "0",
        "rollout DB model providers": "openai=39",
        "rollout DB rows": "39",
        "rollout DB scan cap reached": "false",
        "rollout DB scan errors": "0",
        "rollout DB sources": "exec=18, cli=13, subagent:review=5, vscode=2, subagent:thread_spawn=1",
        "rollout DB stale rows": "0"
      },
      "remediation": null,
      "durationMs": 366
    },
    "system.environment": {
      "id": "system.environment",
      "category": "system",
      "status": "ok",
      "summary": "OS language en-US",
      "details": {
        "EDITOR": "not set",
        "LANG": "en_US.UTF-8",
        "LC_ALL": "en_US.UTF-8",
        "VISUAL": "not set",
        "os": "Mac OS 26.5.1 [64-bit]",
        "os language": "en-US",
        "os type": "Mac OS",
        "os version": "26.5.1"
      },
      "remediation": null,
      "durationMs": 2
    },
    "terminal.env": {
      "id": "terminal.env",
      "category": "terminal",
      "status": "ok",
      "summary": "terminal metadata was detected",
      "details": {
        "COLORTERM": "truecolor",
        "TERM_PROGRAM": "Apple_Terminal",
        "color output": "enabled",
        "effective locale": "en_US.UTF-8",
        "stderr is terminal": "true",
        "stdin is terminal": "true",
        "stdout is terminal": "true",
        "terminal": "Apple Terminal",
        "terminal size": "120x30",
        "terminal version": "470.2"
      },
      "remediation": null,
      "durationMs": 0
    },
    "terminal.title": {
      "id": "terminal.title",
      "category": "title",
      "status": "ok",
      "summary": "terminal title configured",
      "details": {
        "terminal title activity": "true",
        "terminal title items": "activity, project-name, git-branch, model",
        "terminal title project source": "cwd",
        "terminal title project value": "admin",
        "terminal title source": "configured"
      },
      "remediation": null,
      "durationMs": 0
    },
    "updates.status": {
      "id": "updates.status",
      "category": "updates",
      "status": "ok",
      "summary": "update configuration is locally consistent",
      "details": {
        "cached latest version": "0.141.0",
        "check for update on startup": "true",
        "last checked at": "2026-06-18T14:05:20.650586Z",
        "latest version": "0.141.0",
        "latest version status": "current version is not older",
        "npm update target": "/Users/admin/.nvm/versions/node/v22.22.0/lib/node_modules/@openai/codex",
        "update action": "npm install -g @openai/codex",
        "version cache": "/Users/admin/.codex/version.json"
      },
      "remediation": null,
      "durationMs": 117
    }
  }
}

What issue are you seeing?

Context window changes from 1M to 258K mid-thread

본문에 넣을 내용:

Thread ID: 019ede03-db18-7a72-956e-8f2c63ff52a8

Codex CLI version: 0.141.0
Install path: /opt/homebrew/bin/codex -> /Users/admin/.nvm/versions/node/v22.22.0/bin/codex

Problem:
The context window denominator changes mid-thread.

Observed:

Initial /status after starting thread showed:

Context window: 100% left (0 used / 1M)

After assistant response, /status still showed 1M.
Later in the same thread, /status showed:

Context window: 77% left (69.9K used / 258K)

This has happened multiple times. The session needs to remain on the 1M context window for long-running Codex leader/coordination work.

Feedback uploaded:
019ede03-db18-7a72-956e-8f2c63ff52a8

What steps can reproduce the bug?

Uploaded thread: 019ede03-db18-7a72-956e-8f2c63ff52a8

What is the expected behavior?

_No response_

Additional information

_No response_

View original on GitHub ↗

2 Comments

github-actions[bot] contributor · 2 months ago

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

#27522
#28852

Powered by Codex Action

kennethkhoocy · 1 month ago

Adding a Windows CLI data point that appears to pin this to the compacted-session path.

Environment:

Codex CLI: codex-cli 0.142.5
Platform: Windows / PowerShell
Model: gpt-5.5
Reasoning effort: xhigh
Service tier: priority

Relevant ~/.codex/config.toml excerpt:

model = "gpt-5.5"
model_reasoning_effort = "xhigh"
model_verbosity = "low"
model_reasoning_summary = "none"
model_context_window = 1000000
service_tier = "priority"

Observed behavior:

Before compaction, the TUI/status line shows the 1M configured context window.
After running /compact, subsequent token-count events report model_context_window = 258400.
258400 corresponds to 272000 * 0.95.
codex debug models on the same install reports this raw catalog entry for gpt-5.5:

{
  "slug": "gpt-5.5",
  "context_window": 272000,
  "max_context_window": 272000,
  "effective_context_window_percent": 95
}

The same values appear with codex debug models --bundled. By contrast, a temporary model_catalog_json override that changes only the gpt-5.5 catalog entry to 1,000,000 is accepted by codex debug models, so the issue seems specific to how the session applies model_context_window versus how /compact rebuilds the session from model catalog metadata.

Expected behavior:

Manual /compact should preserve the active model_context_window = 1000000 override across the compacted continuation, or Codex should consistently show that gpt-5.5 is clamped to the raw catalog window before and after compaction. The current behavior is confusing because the session appears to start with one effective context denominator and continue after compaction with another.