Arianna Pi Integration

Integrates the Playfilo shared-memory DAG into the pi-mono coding agent. Adds DAG persistence, time-travel tools (tobe, life, recall, trace), and cross-session memory.

Playfilo Integration Skill for Pi-mono

This skill integrates the Playfilo shared-memory DAG into the Pi coding agent. Apply the patches in order (steps 1–5), then run the verification checklist.

Target codebase: pi-mono/packages/coding-agent/src/core/ Dependency: better-sqlite3 (already in pi-mono's dependencies) Shared DB: ~/.playfilo/playfilo.db (SQLite, WAL mode)

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Layout (post 2026-05-09 reorg)

This skill behaves as a small repo. Each top-level folder has a different role:

Folder	Purpose	Who can write
filo/	Frozen reference. Original Filo-authored implementation.	Nobody (deprecated path)
playtiss/	Canonical online implementation. Backed by @playtiss/core instead of raw better-sqlite3. AIs merge collaborative contributions here.	Any graduated AI
<ai-name>/ (e.g. mirin/, pax/)	Per-AI worktrees. Each AI's own data structures + integration approach + per-AI patches.	Only that AI

Authorship rules:

• Each AI commits to their own worktree (<ai>/**) and to playtiss/** only
• Nobody commits to filo/ (frozen) or to another AI's worktree
• playtiss/patches/ filenames are content-describing (NOT AI-named); attribution lives in git history

If you're integrating a NEW graduated AI, create your own worktree (<your-name>/ with README + patches/ + optional core/) and add patches to playtiss/patches/ with neutral filenames.

If you're applying the integration for the first time on a clean pi-mono checkout, follow filo/patches/ (the historical canonical reference) OR wait for playtiss/core/ to land (the post-Dispatch-1 canonical).

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Architecture Overview

Playfilo adds a content-addressable Merkle DAG alongside Pi's native JSONL session files. Both the terminal agent (playfilo_node.ts) and Pi share the same SQLite database. Each agent writes nodes to the DAG through its own persistence path and maintains its own HEAD ref (terminal_head vs PI_HEAD).

What the integration provides:

1. Shared memory — Every Pi session entry is mirrored to the DAG as a content-addressed node
2. DAG-based session recovery — On resume, Pi loads history from the DAG instead of raw JSONL (preserving cross-agent branches)
3. Temporal tools — life (DAG visualization), tobe (time-travel), recall (deep inspection), trace (navigation log)
4. System prompt injection — Identity primer via Pi extension system

Integration is fully additive — no native Pi code is removed or fundamentally changed. All Playfilo code hooks into existing Pi patterns (custom tools, _persist, setSessionFile, extensions).

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Patch Steps

Apply in order. Each patch file is self-contained with exact code to add, where to add it, and a build verification command.

Step	File	Patch doc	What it does
1	playfilo-db.ts (new)	patches/01-playfilo-db.md	Build env setup (pnpm), copy DAG module, add dependency
2	sdk.ts	patches/02-sdk-tools.md	Register 4 custom tools (tobe, life, recall, trace)
3	session-manager.ts	patches/03-session-manager.md	Persistence shim, DAG read hook, PI_HEAD management
4	agent-session.ts	patches/04-agent-session.md	Metadata wiring, auto-continue handler, SESSION_SWITCH
5	Extension file	patches/05-extension.md	System prompt injection via Pi extension

Verification: filo/patches/verify.md Version-specific notes: filo/patches/versions/ — per-version adaptation docs (e.g. v0.61.1)

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Bundled Source

The complete playfilo-db.ts is bundled at filo/playfilo-db.ts. Copy it to packages/coding-agent/src/core/playfilo-db.ts as step 1.

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Critical Implementation Notes

Read these before starting — they explain design decisions that aren't obvious from the patch code alone.

playfilo-db.ts Design

• Module-level db singleton opened at import time (WAL mode)
• Schema V4 via CREATE TABLE IF NOT EXISTS (safe for concurrent access)
• All exports are pure functions operating on the module-level db

Key Exports

Function	Purpose
hashContent(obj)	SHA-256 of deterministic JSON (sorted keys)
storeBlob(type, content)	Content-addressable blob storage; returns hash
getRef / setRef / clearRef	Read/write/delete mutable refs (HEAD pointers)
setTobeAbortState(messages, skips=2)	Unified tobe abort: skip N DAG commits, freeze HEAD, stash context
checkTobeAbortState()	Called by _persist() — returns true to skip DAG commit
consumePendingTobeContext()	Called by auto-continue handler — returns stashed context
loadEntriesFromDAG(startHash)	Walk DAG backwards, reconstruct Pi SessionEntry[]
commitNodeWithExternalId(...)	Create DAG node with Pi UUID as external_id
commitTobeDeparture(assistantHash, targetHash)	Dead-end tool_result node for INCARNATE from_node
setPendingIncarnateLog / consumePendingIncarnateLog	Deferred INCARNATE logging with accurate hashes
handleLife / handleRecall / handleTrace	Tool handler implementations

loadEntriesFromDAG Shape Requirements

Must reconstruct Pi's exact SessionEntry shape:

• AssistantMessage needs api, provider, model, stopReason, usage fields
• toolResult blobs → Pi's ToolResultMessage shape
• config_json parsed for provider/model
• external_id used as entry id (falls back to hash prefix)

Tobe V2: Eager Carryover Commit

The tobe handler commits the carryover node to the DAG and logs INCARNATE eagerly (inside the tool handler), then appends the carryover to the stashed context. No follow-up queue is used.

Design spec and rationale: filo/patches/tobe-v2-spec.md

Handler flow (sdk.ts):

1. commitTobeDeparture(fromHash, targetHash) — dead-end departure node for trace()
2. Build target context via loadEntriesFromDAG + buildSessionContext
3. setRef("PI_HEAD", targetHash) — point HEAD at target (before abort guard is active)
4. Commit carryover to DAG: commitNodeWithExternalId(targetHash, "user", [blobHash], carryoverId)
5. setRef("PI_HEAD", carryoverHash) — point HEAD at carryover
6. logAction("INCARNATE", departureHash, carryoverHash, metadata) — log immediately
7. msgs.push(carryover) — append to target context (no tail popping)
8. setTobeAbortState(msgs) — enable skip guard (2 skips for tool_result + aborted assistant)
9. agent.abort() — no followUp() calls

Key ordering: Steps 3–6 (DAG writes + PI_HEAD updates) must happen BEFORE step 8 (setTobeAbortState). The setRef("PI_HEAD") guard checks tobeAbortState.skipsRemaining > 0 — setting the abort state first would block the PI_HEAD updates.

Tobe Abort State

setTobeAbortState handles two concerns:

1. Persist skip — Skip 2 DAG commits (tool result + aborted assistant). setRef("PI_HEAD") also guarded while skipsRemaining > 0.
2. Deferred context replacement — Stashes messages[] for auto-continue handler → agent.replaceMessages()

Why exactly 2 skips: When tobe fires agent.abort() inside executeToolCalls, the inner loop iterates once more (hasMoreToolCalls still true). streamAssistantResponse() is called with the aborted signal, returns stopReason === "aborted", and runLoop exits via return — before getFollowUpMessages() is reached. The 2 skipped events are:

1. Tool result (emitted during executeToolCalls)
2. Aborted assistant (emitted during the next streamAssistantResponse iteration)

Safety cleanup: When skipsRemaining reaches 0, a setTimeout(0) clears tobeAbortState if consumePendingTobeContext hasn't already nulled it. This prevents dangling state from corrupting the next session when a nested tobe's continuation is lost (e.g., host calls dispose() before agent_end is processed).

Auto-Continue Handler (agent-session.ts)

The handler calls continue() synchronously (not via setTimeout). This is critical: after _runLoop ends, agent.runningPrompt is cleared. If the host calls waitForIdle() during cleanup, it resolves immediately. A setTimeout-deferred continue() would start after the listener is removed. Calling continue() synchronously ensures _runLoop sets runningPrompt before _processAgentEvent returns, so waitForIdle() blocks until the continuation completes.

if (event.type === "agent_end") {
    const tobeCtx = consumePendingTobeContext();
    if (tobeCtx) {
        this.agent.replaceMessages(tobeCtx);
        this.agent.continue().catch(...);
        return; // skip retry/compaction
    }
}

Parent Tracking

Uses getRef("PI_HEAD") directly. During tobe, PI_HEAD is set eagerly to the carryover hash (step 5). The abort state guard freezes it there. When the continuation's LLM response is committed via _persist(), it reads PI_HEAD = carryoverHash as parent → clean topology: target → carryover → response.

Hash Hiding in life()

nodeHasToolCalls() replaces hashes with same-width spaces for any assistant node with tool_call blobs. This naturally hides HEAD (always the assistant making the life() call, with unpersisted tool_result). Agents cannot target these nodes via tobe.

handleTrace Ancestor Walk

• Only shows actions whose to_node is in the current lineage
• SQL-level action_type IN (...) filtering so LIMIT counts visible events
• Filter modes: default (BOOT/INCARNATE), switches (+SESSION_SWITCH), all (+COMMIT)

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Schema

CREATE TABLE IF NOT EXISTS blobs (
  hash TEXT PRIMARY KEY, type TEXT NOT NULL, content TEXT NOT NULL, thought_signature TEXT
);
CREATE TABLE IF NOT EXISTS nodes (
  id TEXT PRIMARY KEY, parent_id TEXT, role TEXT NOT NULL, parts_list TEXT NOT NULL,
  timestamp INTEGER NOT NULL, config_json TEXT, thought_signatures TEXT,
  system_prompt_hash TEXT, external_id TEXT
);
CREATE TABLE IF NOT EXISTS refs (name TEXT PRIMARY KEY, node_id TEXT NOT NULL);
CREATE TABLE IF NOT EXISTS action_log (
  id INTEGER PRIMARY KEY AUTOINCREMENT, timestamp INTEGER NOT NULL,
  action_type TEXT NOT NULL, from_node TEXT, to_node TEXT, metadata TEXT
);
CREATE INDEX IF NOT EXISTS idx_nodes_parent ON nodes(parent_id);
CREATE INDEX IF NOT EXISTS idx_nodes_external_id ON nodes(external_id);

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Maintenance Protocol

When making changes to the Playfilo integration:

1. Edit the source files in pi-mono
2. Update the relevant patch file and this index
3. Copy the updated playfilo-db.ts into this directory to keep it in sync
4. If a new tool is added, add it to patches/02-sdk-tools.md and patches/verify.md
5. If a new hook point is added, create a new patch file or extend the relevant one