pi-mega-compact

⚠️ LTS — patches only (2026-08-13). This extension is maintained for bug fixes only. New feature development has moved to radcode, a Rust pi.dev replacement that has ported mega-compact's compaction/recall/dedup/RAPTOR stack. See docs/LTS.md and docs/SUCCESSION.md.

A local-first context compressor for the pi coding agent. Keeps long sessions running without overflowing the context window. Local by default — no cloud, no API calls, no telemetry. Bring your own localhost embedder (Ollama, ONNX, TEI) for better semantic matches, or opt in to a remote endpoint if you need to.

Features

• Auto-compaction — the store watches context pressure and compacts quietly in the background. You'll notice when a long session just stays long while the token gauge rests comfortably far from the ceiling.
• Small-context models are the point — models with 32k windows (GLM-4.7 etc.) are a first-class case, not an afterthought. The gate accounts for the provider's full declared output reserve, and the live-trim budgets the tail so input + reserve + margin <= window — no truncation loops at the overflow edge. Token accounting counts everything the provider actually receives (thinking blocks, tool-call arguments included), not just visible text.
• Two-layer compaction — every LLM call sees a live trim of the context window, and every trim is checkpointed to SQLite so a crash or a /clear never loses the work.
• Semantic dedup, three layers deep — exact hash (L0) -> MinHash/LSH (L1) -> cosine over trigram embeddings (L2). The dedup audit log records per-tier decisions with similarity scores for tuning.
• RAPTOR memory hierarchy — decisions you made an hour ago don't scroll off; they get packed up as hierarchical checkpoints and re-inlined the moment your next session asks for them. Multi-level retrieval (leaves + summary clusters) is on by default. Since v0.11.10, RAPTOR tree updates are incremental (no full rebuild) — enabled by default.
• Per-turn tracking + rewind. Every turn, checkpoint, and recall hit lands as a row in an isolated turns.db — turns, turn_recall, conversation_forks. The dashboard Turns tab shows turn-by-turn memory: context pressure, the compact epoch that superseded each turn, and the exact checkpoints recalled into it. A fork action branches a conversation at any turn (carrying its recall set); a rewind action queues an intent the host consumes at the next before_agent_start. The TurnStore is contract-first (capability-gated reader/writer/admin views) so the same spine backs the dashboard, the TUI, or an API gateway.
• Cross-repo recall — doors you close in one repo don't reopen when you move to another. A decision stored while hacking repo A is a recall hit the next time you're in repo B.
• Durable memory — on a cadence the store auto-reviews and safe-keeps decisions, facts, and preferences as first-class RAG memories, so long-running projects remember what mattered.
• Prompt-cache optimization — message separation + cache striping (both default ON; disable with MEGACOMPACT_MESSAGE_SEPARATION=0 / MEGACOMPACT_CACHE_STRIPING=0). Targets 82-90% cache hit rate by structuring context around provider cache boundaries.
• Context health + KV cache poison validation (v0.12) — a real-time composite 0-1 health score per turn from five sub-scores (drift, output quality, error rate, cache health, cache poison). Catches garbled/hallucinated output and provider-side KV-cache corruption before they waste tokens — the failure mode where a large-context model (e.g. DeepSeek V4 Flash, 1M window) degrades at <1% usage. Tri-layer cache poison validation: prefix hash (L1 FNV-1a), output-quality-by-cache-hit (L2 semantic), error-rate correlation (L3 behavioral). The dashboard Health tab shows a gauge, sparkline, sub-score bars, alerts, and per-model breakdown. Auto-mitigation (force compaction on degraded context, prefix break on poisoned cache) is default OFF — toggle it in the Maintenance tab.
• RAG suite — query reformulation (TF-IDF + RRF), tiered routing (L0 cache -> L1 FTS5 -> L2 PGlite), recall-quality metrics (CRAG), memory graph, and HyDE (hypothetical document embeddings). All default ON with graceful fallback — opt out via MEGACOMPACT_<NAME>_DISABLED=true. HyDE auto-activates only when an LLM embedder (Ollama/HTTP) is configured — it's a no-op with the default TrigramEmbedder. The dashboard Metrics tab (v0.13) shows RAG recall-quality metrics (pass rate, avg lift, telemetry turns, HyDE runs) and the Overview tab has a RAG health card. Toggle any flag from the dashboard Setup tab.
• Debug bundle — Maintenance tab in the dashboard has a Gather Debug Logs button that collects events, config, and store state into a shareable archive for bug reports.
• Local-first by default — node:sqlite + trigram embeddings by default, zero calls off your machine. Bring your own localhost embedder (Ollama, ONNX, TEI) for better semantic matches — the embedder endpoint is loopback-only by default (MEGACOMPACT_ALLOW_REMOTE_EMBEDDER=1 opts in to a remote/third-party endpoint). The optional dashboard is localhost-only. No cloud, no API calls, no telemetry. The optional Cost API lookup (MEGACOMPACT_COST_API_ENABLED, default OFF) is the one network exception — it fetches model pricing from a user-configured endpoint to show real $/token rates in the dashboard.
• Team-run aware — fine-grained durable trim fires at agent settle during sub-agent runs, so long multi-agent work doesn't just collapse at the end.
• Multi-pi dashboard — one dashboard tab per active pi process with the context stack, per-repo stats, and a live SSE feed across all of them. The React SPA (Tailwind v3 + shadcn/ui, v0.13) has 12 lazy-loaded tabs — Overview, Cache, Sessions, and Turns (per-turn memory + recall + rewind) are primary; Repos, Events, Setup (embedding wizard + comprehensive settings panel), Metrics (perf latency/TPS/CPU + RAG recall quality), Wiki (auto-categorizing topic browser + evolution graph), Memory Map (D3 graph), Maintenance (debug bundle), and Health (context-health gauge + cache-poison alerts) are advanced. The Overview tab dynamically resolves the most recently active repo's snapshot so it always shows live data.
• Auto-categorizing wiki. Every 3 compactions (seeds from turns before that), the store clusters your real memory embeddings (k-means) and labels each cluster with its most discriminative terms (TF-IDF) — no LLM, no Ollama, fully local. The dashboard Wiki tab (v0.13) browses topics, searches by label or term, drills down into the member memories of each cluster, and shows a topic evolution graph over time. Curation supports rename/merge/split operations with durable overrides that survive full rebuilds.
• Comprehensive settings panel (v0.13.6) — every adjustable MEGACOMPACT_* env var is surfaced in the dashboard Setup tab, grouped by category (RAG Pipeline, Wiki/Turns, Dedup Tiers, Dedup Thresholds, RAPTOR Tuning). Toggle booleans, edit numerics with units, change strings — all write to .mega-compact.env via POST. The regression gate enforces that no new config flag ships without a dashboard entry.
• Stacked memory graph — the dashboard shows memory composition over time from 3 content sources (turns, durable memories, wiki) with a 9-gate validation system and a graph-health indicator. Per-model provider cache breakdown in the Cache tab.

Install

pi install npm:pi-mega-compact

That's it. pi update --extensions pulls updates going forward. npm is the only distribution path — never use .tgz tarballs or symlinks for shipping.

From source (development)

git clone https://github.com/TheArchitectit/pi-mega-compact.git \
  ~/.pi/agent/extensions/pi-mega-compact
cd ~/.pi/agent/extensions/pi-mega-compact
npm install && npm run build

The bundled ./install.sh helper does the symlink + config edit (needs jq).

Usage

Once installed, it runs automatically. Past the context threshold it compacts in the background. On resume, it re-inlines relevant checkpoints silently.

Key commands:

• /mega-compact — manually compact the current session
• /mega-status — show context usage, store stats, version
• /mega-recall [query] — semantic search the store, --cross-repo for all repos
• /mega-memory save|list|search|forget — manage durable memories
• /mega-dashboard — start the localhost dashboard
• /mega-setup — embedding wizard: detects Ollama/llama.cpp, suggests upgrades when recall quality is low

Full command reference: docs/COMMANDS.md

Configuration

Set env vars before starting pi. Defaults are in src/config/dedup.ts.

Variable	Default	Description
MEGACOMPACT_TIER	low	Threshold as % of context window (low=50%, medium=60%, high=70%)
MEGACOMPACT_AUTO	true	Enable auto-compaction
MEGACOMPACT_DEDUP_SIM	0.90	Cosine threshold for near-dup collapse
MEGACOMPACT_CROSSREPO_ENABLED	true	Cross-repo recall on resume
MEGACOMPACT_EMBEDDING_URL	(unset)	BYO localhost embedder endpoint (loopback-only by default)
MEGACOMPACT_ALLOW_REMOTE_EMBEDDER	false	Opt-in: allow non-loopback embedder endpoint (e.g. hosted API)
MEGACOMPACT_TUI_WIDGET	true	Render the above-editor panel
MEGACOMPACT_MESSAGE_SEPARATION	false	Opt-in: separate messages at provider cache boundaries
MEGACOMPACT_CACHE_STRIPING	false	Opt-in: stripe cache stripes across conversation
MEGACOMPACT_QUERY_REFORMULATION_DISABLED	false	Default ON — set true to disable TF-IDF + RRF query reformulation
MEGACOMPACT_TIERED_ROUTER_DISABLED	false	Default ON — set true to disable L0->L1->L2 recall routing
MEGACOMPACT_RECALL_METRICS_DISABLED	false	Default ON — set true to disable CRAG recall quality metrics
MEGACOMPACT_MEMORY_GRAPH_DISABLED	false	Default ON — set true to disable memory graph
MEGACOMPACT_HYDE_DISABLED	false	Default ON — set true to disable HyDE (auto-activates only with LLM embedder)
MEGACOMPACT_MEMORY_GRAPH_SEED_TURNS	true	Seed memory graph from turns (default ON)
MEGACOMPACT_WIKI_SEED_FROM_TURNS	true	Seed wiki from turns (default ON)
MEGACOMPACT_RAPTOR_INCREMENTAL	true	Incremental RAPTOR updates (default ON)
MEGACOMPACT_CONTEXT_HEALTH	true	Master switch: per-turn context-health composite score
MEGACOMPACT_CONTEXT_HEALTH_DRIFT	true	Sub-score: topic drift + error escalation + prefix instability
MEGACOMPACT_CONTEXT_HEALTH_OUTPUT_QUALITY	true	Sub-score: repetition, coherence, token-salad detection
MEGACOMPACT_CONTEXT_HEALTH_CACHE_POISON	true	Sub-score: tri-layer KV cache poison validation
MEGACOMPACT_CONTEXT_HEALTH_MITIGATE	false	Opt-in: auto-compaction on degraded context, prefix break on poisoned cache
MEGACOMPACT_WIKI_ENHANCED	true	Enhanced wiki with topic overrides + evolution tracking
MEGACOMPACT_WIKI_INCREMENTAL	true	Incremental wiki updates (no full rebuild)
MEGACOMPACT_AUTO_WIKI	true	Auto-generate wiki from turns
MEGACOMPACT_NEW_UI	true	Use the new Tailwind/shadcn dashboard shell
MEGACOMPACT_COST_API_ENABLED	false	Opt-in: fetch model pricing from an external API (PREVENT-PI-004 applies to defaults; opt-in features are exempt). Enriches dashboard cost data for models not in the local pricing table
MEGACOMPACT_COST_API_URL	(unset)	OpenRouter-compatible model pricing endpoint (e.g. https://openrouter.ai/api/v1/models). Only contacted when MEGACOMPACT_COST_API_ENABLED=true
MEGACOMPACT_OVERFLOW_HEADROOM	true	Fire compaction before input + output reserve + margin exceeds the window (prevents provider 400s on small-context models)
MEGACOMPACT_OUTPUT_RESERVE_PCT	0.30	Fallback output reserve as a fraction of the window when the model's declared maxTokens is missing or implausible
MEGACOMPACT_OUTPUT_ERROR_COMPACT	true	One-shot force-compact when a response truncates mid-output (stopReason: length)
MEGACOMPACT_WIRE_OVERHEAD	true	Add the provider's invisible request overhead H (system prompt + tool definitions + extension systemPrompt prepends — never in the stored transcript) back into the token estimate for the headroom gate and tail cap; H is a per-model EMA of observed wire samples, else MEGACOMPACT_WIRE_OVERHEAD_DEFAULT_PCT × window. Closes the small-context-model 400 loop (attempt #9). OFF = byte-identical v0.21.11
MEGACOMPACT_WIRE_OVERHEAD_DEFAULT_PCT	0.15	Fraction of the context window used as the overhead H when no wire sample has been observed yet for the model (clamped 0–0.85). Percent-based: identical math at every window size

Full config reference: docs/CONFIGURATION.md

Architecture

extensions/          Pi entry points (mega-compact, mega-trim, dashboard)
src/engine.ts        Trident pipeline (supersede -> collapse -> cluster)
src/vectorStore.ts   Local vector DB (add/search/dedupe)
src/compact.ts       Summarize / merge / auto-compact
src/memory.ts        Durable memories + auto-review
src/contextHealth.ts Context health composite + KV cache poison validation
src/store/sqlite.ts   node:sqlite store (Node >=22.13)
src/store/vectorIndex.ts  PGlite/HNSW cross-repo index

Detailed architecture: docs/ARCHITECTURE.md

Development

npm run build     # TypeScript compile
npm test          # Build + 4400+ tests
npm run lint      # Type check + guardrails scan

Testing guide: TESTER_GUIDE.md

Tester requests

These areas benefit from real-world usage data. The automated test suite covers correctness, but tuning requires diverse sessions.

• Cosine threshold validation — the 0.90 dedup threshold may need adjustment per content type (try 0.93 for code, 0.87 for prose). Run with MEGACOMPACT_DEDUP_SIM set to different values and report false positives via the debug bundle (Maintenance -> Gather Debug Logs). The dedup audit log (events.log) records similarityScore + matchedId per decision.
• Cross-repo recall quality — enable cross-repo recall and report the relevance-vs-noise ratio from real multi-repo sessions. The Turns tab shows recall hits per turn.
• Dedup layer audit — is MinHash/LSH (L1) catching enough over exact-hash (L0) + cosine (L2) to justify the complexity? If L1 catches <5% additional in your sessions, we may simplify to 2-layer. The dedup audit log has per-tier decisions.
• Compaction death-spiral — v0.11.9 fixed an "Already compacted" loop that made sessions unrecoverable (critical-over escape hatch forces a trim + durable compact at >=90% context). If you see this recur, report it immediately with the debug bundle.
• Share debug bundles — when reporting any issue, first gather from Maintenance -> Gather Debug Logs and include the archive.

Troubleshooting

npm lifecycle scripts disabled

Some package managers disable lifecycle scripts by default. PGlite and @mongodb-js/zstd need scripts enabled to build their native components.

# Re-enable install scripts
npm config set ignore-scripts false
npm install

# Or allow scripts for specific packages only
npm install --install-strategy=linked

node:sqlite not found / experimental flag required

pi-mega-compact requires Node >=22.13 for the built-in node:sqlite module. If you're on an older version or your Node build doesn't include it by default:

export NODE_OPTIONS="--experimental-sqlite"
pi

Add the export to your shell profile (.bashrc, .zshrc, etc.) to make it permanent.

License

BSD 3-Clause

Support

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