A transparent Claude Code and Codex plugin that preserves working state around /compact.
> /plugin marketplace add u-ichi/compact-plus> /plugin install compact-plus@compact-plus
Japanese README | Architecture
A transparent Claude Code and Codex plugin that preserves working state around /compact. It does not replace either runtime's compaction algorithm; it augments compaction through documented hooks.
additionalContextNot verified/compactadditionalContext, so the agent keeps its bearings during the last few turns before compaction actually runs. This does not change the compaction algorithm itself; it is a focus aid that reduces late-session drift between warn and the real /compact/compact-plus skill for manual state captureAfter installation, just run /compact as usual. No additional action is required — the flow is fully transparent.
/compact and auto-compaction trigger the same hook pathSessionStart(source=compact) before the first post-compaction promptOptional enhancements:
/compact keep the security-related decisions to send priority guidance to the state-generation LLM/compact-plus manually right before compaction if you want to leave richer recovery notes; this switches to the fallback path where the agent writes the structured state itselfclaude -p or codex execclaude -p --model claude-sonnet-5 --effort medium as the primary backend and codex exec --model gpt-5.3-codex-spark as the fallback backendgpt-5.4 or gpt-5.5Add this GitHub repository as a marketplace, then install the plugin from it.
claude plugin marketplace add u-ichi/compact-plus --scope user
claude plugin install compact-plus@compact-plus
Add the same GitHub repository as a marketplace, then install the Codex plugin.
codex plugin marketplace add u-ichi/compact-plus
codex plugin add compact-plus@compact-plus
Review and trust the hook definitions when Codex prompts. Start a new thread after installation so Codex loads the installed plugin and hooks.
Refresh the GitHub marketplace snapshot, then update or reinstall the plugin.
# Claude Code
claude plugin update compact-plus@compact-plus
# Codex
codex plugin marketplace upgrade compact-plus
codex plugin add compact-plus@compact-plus
For local development, replace u-ichi/compact-plus in the marketplace-add command with the absolute path to this repository.
The plugin reference remains compact-plus@compact-plus.
Following the Claude Code plugin model, write environment variables under the env block in ~/.claude/settings.json. For temporary per-session overrides, shell export also works.
Two environment variables replace the primary and fallback commands as whole shell commands.
| env var | Meaning |
|---|---|
COMPACT_PLUS_PRIMARY_BACKEND | Complete shell command for the primary backend. Set to an empty string ("") to skip the primary backend |
COMPACT_PLUS_FALLBACK_BACKEND | Complete shell command for the fallback backend. Set to an empty string to skip the fallback backend |
Environment variables available inside those commands:
$SYSTEM_PROMPT: the LLM system prompt from prompts/state-summary.md$SESSION_ID: Claude Code session id$TRANSCRIPT_PATH: transcript JSONL path$MAX_OUTPUT_TOKENS: LLM output capDefault values are embedded in hooks/precompact-state-summary.sh.
Example ~/.claude/settings.json override for a lower-cost Haiku backend:
{
"env": {
"COMPACT_PLUS_PRIMARY_BACKEND": "claude -p --model claude-haiku-4-5-20251001 --effort low --permission-mode dontAsk --output-format text --no-session-persistence --system-prompt \"$SYSTEM_PROMPT\""
}
}
Example replacing the primary backend with Codex Spark (requires ChatGPT Pro; served through Cerebras for higher throughput):
{
"env": {
"COMPACT_PLUS_PRIMARY_BACKEND": "tmp=$(mktemp \"${TMPDIR:-/tmp}/compact-plus-codex.XXXXXX\"); { printf \"%s\\n\\n\" \"$SYSTEM_PROMPT\"; cat; } | codex exec --model gpt-5.3-codex-spark --sandbox read-only --skip-git-repo-check --dangerously-bypass-hook-trust --ignore-user-config --ephemeral --output-last-message \"$tmp\" - >/dev/null && cat \"$tmp\"; status=$?; rm -f \"$tmp\"; exit \"$status\""
}
}
Codex output can prepend a CLI preamble to stdout, so --output-last-message "$tmp" is used to capture only the final message. This mirrors the default fallback implementation.
Example disabling the fallback:
{
"env": {
"COMPACT_PLUS_FALLBACK_BACKEND": ""
}
}
| env var | default | Meaning |
|---|---|---|
COMPACT_PLUS_TRANSCRIPT_MODE | incremental | Transcript selection mode: incremental, head-tail, or tail |
COMPACT_PLUS_TRANSCRIPT_HEAD_TURNS | 5 | Number of turns to keep from the head side |
COMPACT_PLUS_TRANSCRIPT_TAIL_TURNS | 25 | Number of turns to keep from the tail side |
COMPACT_PLUS_TRANSCRIPT_HEAD_KB | 10 | Head-side byte cap in KB |
COMPACT_PLUS_TRANSCRIPT_TAIL_KB | 40 | Tail-side byte cap in KB |
COMPACT_PLUS_RAW_DELTA_FACTOR | 20 | Incremental mode reads at most TAIL_KB * N of raw transcript delta before squashing. Set 0 for unbounded |
COMPACT_PLUS_INCREMENTAL_REFRESH | 10 | Full rebuild every N runs. Set 0 to disable |
COMPACT_PLUS_MAX_OUTPUT_TOKENS | 4096 | LLM output cap for backends that read it |
COMPACT_PLUS_BACKEND_TIMEOUT | 80 | Per-backend timeout in seconds. Primary and fallback run serially inside the 180s hook budget. Set 0 to disable |
COMPACT_PLUS_SQUASH_ENABLED | 1 | Enables or disables tool result squash |
COMPACT_PLUS_SQUASH_READ_LINES | 100 | Replaces Read tool output above N lines with [Read: N lines from path] |
COMPACT_PLUS_SQUASH_BASH_CHARS | 500 | Replaces Bash output above N characters with [Bash: exit code, N chars output] |
COMPACT_PLUS_TWO_PASS | 1 | Enables or disables two-pass self-critique |
Claude Code and Codex use separate settings:
| Runtime | env var | default | Source |
|---|---|---|---|
| Claude Code | COMPACT_WARN_THRESHOLD | base repository setting | home/hooks/claude/statusline.sh writes the marker consumed by this plugin |
| Codex | COMPACT_PLUS_CODEX_WARN_THRESHOLD | 75 | compact-plus reads the latest token-count event from the current thread rollout |
Both values are context usage percentages. Changing one does not change the other. Codex uses the same effective-window basis as its context display by excluding the current 12,000-token fixed baseline. Codex also verifies that the rollout's session_meta.id matches the current session_id; missing, malformed, or mismatched rollout data produces no notification.
/compact ArgumentsWhen you pass natural-language instructions, such as /compact keep the important design decisions, compact-plus forwards those instructions to the state-generation LLM as priority guidance.
precompact-transcript-backup.sh copies the transcript JSONL to ~/.claude/backups/transcripts/ or ${CODEX_HOME:-$HOME/.codex}/backups/transcripts/precompact-state-summary.sh applies semantic chunking and tool output squash to the transcript, then calls the primary or fallback backend and writes the 10-section state filecompaction-recovery.sh resets the warning cooldown, and either consumes the injected mark left by SessionStart or writes a recovery marker when no injection has happened yetsessionstart-compaction-recovery.sh handles SessionStart(source=compact) for both Claude Code and CodexadditionalContextSessionStart(source=compact) before PostCompact, so on the first compaction there is no marker yet; the hook injects on the strength of the state file and leaves an injected mark, and the later PostCompact consumes that mark instead of arming a marker. Codex dispatches PostCompact first, so the marker already exists and SessionStart consumes it. Either way the state is injected exactly onceuserpromptsubmit-compaction-recovery.sh stays registered as the fallback channel. Codex dispatches the start hook to root threads only, so a thread-spawn subagent receives no start hook after compaction and recovers through the next UserPromptSubmit; parent messages reach a subagent as user input. The marker is consumed once, so a thread that already recovered at SessionStart is a no-op on the following promptuserpromptsubmit-compact-plus-reminder.sh consumes warn markers and injects a lightweight notification plus a three-line state recitation when availablesessionstart-export-session-id.sh writes export CLAUDE_CODE_SESSION_ID=<id> to $CLAUDE_ENV_FILE so the /compact-plus skill can obtain the session id through the bundled scripts/get-session-id.sh wrapper without depending on any file outside the plugin/compact-plus skill)
SKILL.md 10-section procedure and writes the state file manuallyState files start with # Compact Prep State and use the same 10-section order in both the manual skill and LLM-generated output.
## Active Plan## Current Phase## TaskList Summary## Session Decisions## Constraints and Blockers## Worker Topology## Skills Invoked## Editing Files## Failed Attempts## Recovery Notes| path | writer | reader | Purpose |
|---|---|---|---|
${TMPDIR}/claude-compact-state/<session_id>.md | precompact-state-summary.sh / /compact-plus skill | recovery hook / agent | Pre-compaction state |
${TMPDIR}/claude-compact-state-offset/<session_id> | precompact-state-summary.sh | precompact-state-summary.sh | Incremental byte offset |
${TMPDIR}/claude-compact-state-counter/<session_id> | precompact-state-summary.sh | precompact-state-summary.sh | Refresh cycle counter |
${TMPDIR}/claude-compacted/<session_id> | compaction-recovery.sh | sessionstart-compaction-recovery.sh / userpromptsubmit-compaction-recovery.sh | One-shot PostCompact marker |
${TMPDIR}/claude-compact-injected/<session_id> | sessionstart-compaction-recovery.sh | compaction-recovery.sh | Injected mark: SessionStart already delivered the state, so PostCompact skips the marker |
View @u-ichi’s profileA Claude Code / Codex CLI plugin that lets you review agent-generated HTML documents with inline comments — and have the agent read those comments, reply, and improve the document in the next iteration.
@u-ichicompact-plus is a Claude Code plugin with 1 hand-picked skill, indexed on Flowy in the Agent Memory category. Install it with the command on its page. It includes compact-plus. Its skills do not fire on their own yet. Request auto-invocation to have Flowy route them as you prompt. Free and open source.
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