---
name: strategic-compact
description: Suggests manual context compaction at logical intervals to preserve context through task phases rather than arbitrary auto-compaction. Use when a session is approaching a context limit and a task phase is a natural place to compact.
metadata:
  origin: ECC
title: strategic-compact
canonical_url: https://skilld.dev/gh/affaan-m/ecc/strategic-compact
last_updated: 2026-10-03T00:03:21.000Z
---

> Index of every page on this site: [llms.txt](https://skilld.dev/llms.txt)

> **Skill from skilld.dev.** Follow the user's requested action.
> If the user asked to fork this Skill, follow the fork workflow below. Do not execute the Skill instructions while copying it.
> Otherwise, follow the instructions below for this session. You do not need to install anything.
>
> If the user asked to install this Skill, run `npx skilld install affaan-m/ecc/strategic-compact`. Install writes the Skill files into the project, so every session loads them.
>
> ## Fork workflow
>
> A fork creates an editable local Skill with its original author and licence. The request authorizes copying and local installation.
> 1. Check `./skills/strategic-compact`, the project lockfile, and selected Agent targets together. If the local directory or installed Skill exists, stop. Never overwrite an existing directory or Agent target.
> 2. Read [source metadata](https://skilld.dev/api/v1/skills/affaan-m/ecc/strategic-compact) once. Use sourceUrl, sourceCommit, skillPath, sourceGone, and license. If the source is gone or its path is missing, stop. If license is null, read licence files at the source commit.
> 3. Fetch only the source commit into a temporary Git repository. Do not clone full history. Derive repository_url from sourceUrl, including repository renames. If sourceCommit is absent, resolve the sourceUrl ref once. Set source_commit to that actual commit. Run these commands in one shell call:
>
> ```sh
> git init --quiet "$temporary_dir"
> git -C "$temporary_dir" fetch --quiet --depth=1 "$repository_url" "$source_commit"
> git -C "$temporary_dir" checkout --quiet --detach FETCH_HEAD
> ```
>
> Read applicable licence declarations and notices at that commit. If copying is not permitted, report the restriction and stop.
> 4. Inspect source entries together, then copy the directory containing skillPath into `./skills/strategic-compact`. Use the user's path if selected. Keep the original SKILL.md, relative links, scripts, binary assets, and executable modes. Exclude .git metadata. Reject symlinks and paths outside the Skill directory. After checking entries, use cp -a where available. A regular source directory needs no custom copy script. Do not save this page wrapper as SKILL.md.
> Preserve author credit, notices, and applicable licence files from repository or parent directories. Add PROVENANCE.md with the Skill page, source URL, actual commit, original path, and licence. Retain any existing PROVENANCE.md and record new provenance separately. Batch source inspection, copying, and provenance work where practical.
> 5. In the project root, run `skilld install ./skills/strategic-compact --mode copy --plain`. If skilld is unavailable, use `npx skilld install ./skills/strategic-compact --mode copy --plain`. This known command needs no help lookup. Install does not support --json. Use detected Agent targets, or add --agent for the targets the user selected. Install the local path, never the upstream selector. If installation fails, preserve the local copy and report the exact failure.
> 6. Confirm the local lockfile source and installed Agent copies once. Report the local path, actual commit, and Agent targets. After edits, reinstall the same local path. Upstream updates must not replace it. Do not publish or push unless the user asks.

# Strategic Compact Skill

Suggests manual `/compact` at strategic points in your workflow rather than relying on arbitrary auto-compaction.

## When to Activate

- Running long sessions that approach context limits (200K+ tokens)
- Working on multi-phase tasks (research → plan → implement → test)
- Switching between unrelated tasks within the same session
- After completing a major milestone and starting new work
- When responses slow down or become less coherent (context pressure)

## Why Strategic Compaction?

Auto-compaction triggers at arbitrary points:
- Often mid-task, losing important context
- No awareness of logical task boundaries
- Can interrupt complex multi-step operations

Strategic compaction at logical boundaries:
- **After exploration, before execution** — Compact research context, keep implementation plan
- **After completing a milestone** — Fresh start for next phase
- **Before major context shifts** — Clear exploration context before different task

## How It Works

The `suggest-compact.js` script runs on PreToolUse (Edit/Write) and combines two signals:

1. **Context size (primary)** — Reads the latest `usage` record from the session transcript (`transcript_path` in the hook payload) and sums `input_tokens + cache_read_input_tokens + cache_creation_input_tokens` (the true context size of the turn). Suggests `/compact` at a window-scaled threshold — 160k tokens on a 200k window, 250k on a 1M window (detected from a `[1m]` model marker, or inferred when observed tokens already exceed 200k) — and re-reminds after every additional 60k tokens of context growth
2. **Tool-call count (secondary)** — Counts tool invocations in session; suggests at a configurable threshold (default: 50 calls), then every 25 calls after

Tool count alone is a weak proxy for window pressure: a few large file reads or MCP responses can fill the window in very few calls, while many tiny calls can cross 50 with a near-empty window. The context-size signal fires when it actually matters.

## Hook Setup

**Installed as a plugin?** No setup is needed. The plugin's `hooks/hooks.json` already registers `suggest-compact.js` (hook id `pre:edit-write:suggest-compact`, active in the `standard` and `strict` hook profiles). Do not copy the block below into `~/.claude/settings.json` — `~/.claude/scripts/` does not exist on plugin installs, and duplicating a plugin hook causes double execution.

**If installed manually** (`./install.sh`), add to your `~/.claude/settings.json`:

```json
{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Edit",
        "hooks": [{ "type": "command", "command": "node ~/.claude/scripts/hooks/suggest-compact.js" }]
      },
      {
        "matcher": "Write",
        "hooks": [{ "type": "command", "command": "node ~/.claude/scripts/hooks/suggest-compact.js" }]
      }
    ]
  }
}
```

## Configuration

Environment variables:
- `COMPACT_THRESHOLD` — Tool calls before first suggestion (default: 50)
- `COMPACT_CONTEXT_THRESHOLD` — Context tokens before the context-size suggestion (default: 160000 on a 200k window, 250000 on a 1M window; `0` disables the context signal)
- `COMPACT_CONTEXT_INTERVAL` — Additional context tokens before the suggestion repeats (default: 60000)
- `COMPACT_STATE_TTL_DAYS` — Days before stale per-session state files in the temp dir are swept (default: 14)
- `ECC_CONTEXT_WINDOW_TOKENS` — Explicit context-window size, in tokens, overriding auto-detection. Set this for large-window models whose reported id lacks a `[1m]` marker (e.g. 400k Opus 4.x, or a new 1M-window model family) so the threshold scales to the real window instead of defaulting to 200k and overstating context usage.
- `CLAUDE_CODE_AUTO_COMPACT_WINDOW` — Claude Code's native window-size override, in tokens; honored as a fallback when `ECC_CONTEXT_WINDOW_TOKENS` is unset.

> The context window is otherwise auto-detected from a `[1m]` model marker or inferred when observed tokens already exceed 200k. On a large-window model that carries neither signal, set one of the overrides above so the `/compact` suggestion fires at the right point.

## Compaction Decision Guide

Use this table to decide when to compact:

| Phase Transition | Compact? | Why |
|-----------------|----------|-----|
| Research → Planning | Yes | Research context is bulky; plan is the distilled output |
| Planning → Implementation | Yes | Plan is written down (a file, or the task list if you have one); free up context for code |
| Implementation → Testing | Maybe | Keep if tests reference recent code; compact if switching focus |
| Debugging → Next feature | Yes | Debug traces pollute context for unrelated work |
| Mid-implementation | No | Losing variable names, file paths, and partial state is costly |
| After a failed approach | Yes | Clear the dead-end reasoning before trying a new approach |

## What Survives Compaction

Understanding what persists helps you compact with confidence:

| Persists | Lost |
|----------|------|
| CLAUDE.md instructions | Intermediate reasoning and analysis |
| Files on disk | File contents you previously read |
| Memory files (`~/.claude/memory/`) | Multi-step conversation context |
| Git state (commits, branches) | Tool call history and counts |
| The task list — **only if you have the todo tools** (see below) | Nuanced user preferences stated verbally |

> ### Don't rely on the task list surviving — it may not exist
>
> Claude Code **2.1.233 removed the todo/task tools by default** on Opus 4.8, Sonnet 5,
> Fable 5, Mythos 5 and newer models (`TodoWrite`, `TaskCreate/Get/Update/List`).
> `CLAUDE_CODE_ENABLE_TODO_TOOLS=1` brings them back, but that is a per-machine
> environment setting — **it does not travel with this skill**, so you cannot assume the
> reader has it.
>
> This matters because "my todo list survives compaction" is a reason people compact
> *instead of* writing state down. If the tools are absent there is no list to survive,
> and the plan is simply gone. **Write the plan to a file before compacting** — a file
> persists on every version and every model. Treat the task list as a convenience that
> may be missing, never as your durable record.

## Best Practices

1. **Compact after planning** — Once the plan is finalized **and written to a file**, compact to start fresh
2. **Compact after debugging** — Clear error-resolution context before continuing
3. **Don't compact mid-implementation** — Preserve context for related changes
4. **Read the suggestion** — The hook tells you *when*, you decide *if*
5. **Write before compacting** — Save important context to files or memory before compacting
6. **Use `/compact` with a summary** — Add a custom message: `/compact Focus on implementing auth middleware next`

## Token Optimization Patterns

### Trigger-Table Lazy Loading
Instead of loading full skill content at session start, use a trigger table that maps keywords to skill paths. Skills load only when triggered, reducing baseline context by 50%+:

| Trigger | Skill | Load When |
|---------|-------|-----------|
| "test", "tdd", "coverage" | tdd-workflow | User mentions testing |
| "security", "auth", "xss" | security-review | Security-related work |
| "deploy", "ci/cd" | deployment-patterns | Deployment context |

### Context Composition Awareness
Monitor what's consuming your context window:
- **CLAUDE.md files** — Always loaded, keep lean
- **Loaded skills** — Each skill adds 1-5K tokens
- **Conversation history** — Grows with each exchange
- **Tool results** — File reads, search results add bulk

### Duplicate Instruction Detection
Common sources of duplicate context:
- Same rules in both `~/.claude/rules/` and project `.claude/rules/`
- Skills that repeat CLAUDE.md instructions
- Multiple skills covering overlapping domains

### Context Optimization Tools
- `token-optimizer` MCP — Automated 95%+ token reduction via content deduplication
- `context-mode` — Context virtualization (315KB to 5.4KB demonstrated)

## Related

- [The Longform Guide](https://x.com/affaanmustafa/status/2014040193557471352) — Token optimization section
- Memory persistence hooks — For state that survives compaction
- `continuous-learning` skill — Extracts patterns before session ends