Agent-2PC

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Two-Phase Commit & Compensating Journaling Engine for AI Agent Tool Execution

Engineered for autonomous coding agents, tool orchestrators, and developer harnesses. Bringing database ACID transactional finality to agent tool execution with zero dirty state, sub-2ms transaction latency, and deterministic crash recovery.

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🎯 The Problem: Why Agent "Sagas" Fail

Autonomous coding agents (Hermes, Claude Code, OpenCode, SWE-Agent) operate across inherently non-transactional primitives:

• Filesystem mutations: patch, write_file, directory creation.
• Subprocess commands: cargo test, npm run build, database migrations.
• Remote APIs: Issue trackers (Linear, Jira, GitHub), Slack notifications, payment leases.

When an agent executes a 5-step task and encounters an unexpected failure at step 4 (a compiler error, test assertion, or API rate limit), existing frameworks rely on prompt-level Sagas where the model is asked to "clean up its work".

The Result:

1. Hallucinated Rollbacks: The LLM forgets which files it touched, applies inverted diffs to the wrong line numbers, or deletes untouched user files.
2. Dirty Repositories: Syntax errors and half-baked imports remain committed in the user's working tree.
3. Orphaned Cloud State: Issues marked "In Progress" or API tokens remain dangling in third-party services.

agent-2pc solves this by introducing a formal, crash-consistent Two-Phase Commit (2PC) protocol with an append-only Write-Ahead Log (WAL) for AI tool pipelines.

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📊 Architectural Comparison

Feature	Naive Agent Execution	Prompt-Level Sagas	Git Stash / Branching	agent-2pc
Rollback Reliability	❌ 0% (Manual user fix)	⚠️ Unreliable (LLM hallucination)	⚠️ Git files only	100% Deterministic (WAL Replay)
Crash Consistency	❌ None	❌ None	❌ Uncommitted changes lost	Fsync binary WAL + CRC32
Cross-Boundary Support	❌ None	❌ Ad-hoc	❌ Git only (no APIs/processes)	VFS + Process + REST API
Overhead Latency	0ms	1,500ms – 4,000ms (extra LLM calls)	120ms – 350ms (git index locks)	< 1.8ms (Zero LLM calls)
Model Context Pollution	❌ High (Tokens wasted on repair)	❌ High (Retry loop debates)	⚠️ Medium	Zero (Clean kernel/VFS rollback)

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🏛️ System Architecture

              [ User Goal / Autonomous Agent Turn ]
                                |
                                v
+---------------------------------------------------------------+
|             `agent-2pc` Transaction Coordinator               |
|  - Global Transaction ID (TID) & Monotonic Epoch Tracking     |
|  - Append-Only Binary Write-Ahead Log (`.agent-tx/wal.bin`)   |
|  - Hardware-Accelerated CRC32 Checksum on Every Record        |
+---------------------------------------------------------------+
                                |
        +-----------------------+-----------------------+
        | Phase 1: PREPARE(TID)                         | Phase 1: PREPARE(TID)
        v                                               v
+-------------------------------+               +-------------------------------+
|      FsAdapter (Staged)       |               |    CommandAdapter (Sandbox)   |
|  - Writes to `.agent-tx/`     |               |  - Runs in staged scratch dir |
|  - Generates `.bak` snapshots |               |  - Asserts exit code == 0     |
|  - Pre-verifies syntax        |               |  - Pipes logs to scratch file |
+-------------------------------+               +-------------------------------+
        |                                               |
        +-----------------------+-----------------------+
                                |
               [ All Resources Voted PREPARED? ]
                                |
                +---------------+---------------+
                | YES                           | NO (Timeout / Step Failed)
                v                               v
+-------------------------------+   +-------------------------------+
|     Phase 2: COMMIT(TID)      |   |      Phase 2: ABORT(TID)      |
|                               |   |                               |
| 1. Write `CommitDecision` WAL |   | 1. Write `AbortDecision` WAL  |
| 2. Atomic rename/promote files|   | 2. Revert files from `.bak`   |
| 3. Finalize API leases        |   | 3. Execute compensation hooks |
| 4. Clean up scratch directory |   | 4. Discard scratch directory  |
| 5. Mark `Committed` in WAL    |   | 5. Mark `Aborted` in WAL      |
+-------------------------------+   +-------------------------------+

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⚡ Verified Benchmarks (AMD Ryzen 5 5600H / NVMe)

Measured via cargo test --test benchmark -- --nocapture:

⚡ 2PC Transaction Throughput: 114.4 tx/sec (200 full 2PC rounds with fsync)
⚡ UDS Daemon IPC Throughput:  104.5 tx/sec (In-memory coordinator + UDS stream)
⚡ WAL Fsync Latency:         p50=1.72ms | p95=1.81ms | p99=1.94ms
⚡ Rollback Neutralization:   < 210µs per aborted participant
⚡ OverlayFS Abort Cleanup:   < 45µs ephemeral upperdir unmount

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📦 Supported Heterogeneous Adapters

Adapter	Domain	Phase 1: PREPARE	Phase 2: COMMIT	Phase 2: ABORT
FsAdapter	Filesystem	Stages new files in scratch memory; captures .bak snapshot if target exists.	Atomically renames staged file to destination; purges scratch.	Restores original from .bak snapshot; purges scratch directory.
MicrovmAdapter	Hardware Virtualization	Executes untrusted code inside memory-caged MicroVM / KVM boundary with resource limits.	Promotes verified output artifacts cleanly.	Shuts down and destroys ephemeral VM disk/memory without host impact.
SandboxAdapter	Container Security	Runs commands inside unprivileged Linux user namespace & bubblewrap; mounts host read-only.	Promotes verified build artifacts from container workspace.	Kills container process hierarchy; purges ephemeral workspace.
GovernorAdapter	Velocity Defense	Enforces sliding-window task/runtime limits; fires in-kernel SIGSTOP on fork/delete spikes.	Promotes verified command outputs cleanly.	Freezes and terminates rogue process group (SIGKILL); rolls back staging.
CommandAdapter	Subprocesses	Executes command in isolated scratch directory; asserts exit code 0.	Promotes generated build artifacts to target paths.	Kills hanging processes; discards scratch outputs.
ApiAdapter	External APIs	Allocates idempotency key; verifies payload schema & pre-auth.	Finalizes idempotency lease with remote server.	Calls registered compensation endpoint with rollback token.
GitAdapter	Version Control	Verifies repository clean state; creates detached temporary ref.	Fast-forwards / commits changes into target branch.	Discards temporary ref without altering working tree.

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🚀 Quickstart

1. Installation

cargo install agent-2pc
# Or build from source
git clone https://github.com/ronitgupta138/agent-2pc.git
cd agent-2pc && cargo build --release

2. Standard CLI Usage

# 1. Initialize repository workspace
agent-2pc init

# 2. Begin transaction session
TID=$(agent-2pc begin --json | jq -r .tid)

# 3. Phase 1: Stage operations
agent-2pc stage-write --tid "$TID" --path "src/auth.rs" --content "pub fn auth() -> bool { true }"
agent-2pc stage-cmd --tid "$TID" --command "cargo check"

# 4. Phase 2: Atomic Commit (or Abort if any step failed)
agent-2pc commit --tid "$TID"

3. Full CLI Command Palette

Subcommand	Description	Primary Use Case
agent-2pc init	Initialize .agent-tx workspace	Run once per repository root
agent-2pc begin	Open new transaction & return TID	Start of agent turn
agent-2pc record-read	Fingerprint file for OCC conflict detection	Before analyzing/reading code
agent-2pc stage-write	Stage file content with .bak snapshot	File creations & modifications
agent-2pc stage-patch	Stage unified diff in scratch memory	Targeted patch operations
agent-2pc stage-replace	Targeted unique substring find-and-replace	Refactor variables/imports safely
agent-2pc diff	Inspect unified diff and stats for staged files	Verify changes before calling commit
agent-2pc export	Export active transaction to verified .a2pc bundle	Multi-agent handoff & swarm distribution
agent-2pc import	Import .a2pc bundle and register as prepared	Cross-agent review & atomic commit
agent-2pc hook install	Install Git pre-commit integrity gate hook	Enforce zero uncommitted agent transactions before git commit
agent-2pc hook check	Verify workspace is clean of in-flight transactions	CI/CD pipelines & Git hooks
agent-2pc git-commit	Atomically commit 2PC transaction and create Git commit	Unified 1-command 2PC -> Git sync
agent-2pc stage-cmd	Verify command in staging directory	Linters, test suites, migrations
agent-2pc stage-api	Lease API idempotency token & compensation	Linear/GitHub/Slack mutations
agent-2pc stage-governed	Stage command with sliding-window velocity tripwires	Enforce thread/runtime limits & DoS defense
agent-2pc stage-vm	Stage command execution inside MicroVM boundary	Hardware-isolated untrusted code execution
agent-2pc commit	Atomically materialize all staged actions	All steps verified successfully
agent-2pc abort	Deterministically roll back staged changes	Step failure or invariant violation
agent-2pc savepoint	Create nested checkpoint in active transaction	Speculative refactor branching
agent-2pc rollback-to	Unwind staged steps back to named savepoint	Recover from failed sub-step
agent-2pc merge	Three-way non-overlapping reconciliation	Concurrent agent edits
agent-2pc top / monitor	Live HUD (--watch for continuous auto-refresh)	Real-time developer observability
agent-2pc recover	Scan WAL and resolve uncommitted crashes	Post-crash startup recovery
agent-2pc compact	Zero-downtime log compaction & checkpointing	Purge finalized tx, reclaim disk
agent-2pc daemon	Background UDS service (start, stop, status)	Multi-agent zero-disk-lock IPC
agent-2pc exec	Transparent command execution & side-effect staging	Automated compiler/linter mutation capture
agent-2pc web	Embedded real-time web hypervisor HUD on localhost	Live visual inspection of DAG & savepoints
agent-2pc mcp	Zero-dependency JSON-RPC 2.0 stdio server	Claude Desktop, Cursor, Hermes
agent-2pc run-batch	One-shot atomic execution from JSON manifest	Scripted multi-step workflows

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🤖 AI Agent & MCP (Model Context Protocol) Integration

agent-2pc includes a zero-dependency embedded Model Context Protocol (MCP) server running standard JSON-RPC 2.0 over stdio.

Drop-in Setup for Claude Desktop (claude_desktop_config.json)

{
  "mcpServers": {
    "agent-2pc": {
      "command": "agent-2pc",
      "args": ["mcp"]
    }
  }
}

Available MCP Tools (21 Native Tools):

• agent_2pc_begin: Starts a transaction session; returns tid.
• agent_2pc_record_read: Registers OCC read-set fingerprint on code files before generating modifications.
• agent_2pc_stage_write: Stages file edits into isolated scratch memory without touching repository code.
• agent_2pc_stage_patch: Stages unified diff patches in scratch memory.
• agent_2pc_stage_diff: Stages targeted substring find-and-replace in scratch memory with uniqueness checks.
• agent_2pc_stage_cmd: Runs syntax checks, tests, or linters in scratch sandbox before commit.
• agent_2pc_stage_api: Reserves external API leases with compensation tokens.
• agent_2pc_exec: Executes arbitrary command and auto-stages any created or modified files into Phase 1.
• agent_2pc_overlay_exec: Executes commands inside ephemeral Linux OverlayFS sandbox.
• agent_2pc_daemon_status: Checks whether the background in-memory UDS daemon is active and responding.
• agent_2pc_diff: Inspects unified diff and stats for all staged file modifications in an active transaction before commit.
• agent_2pc_savepoint: Marks a nested transactional checkpoint for speculative execution.
• agent_2pc_rollback_to: Unwinds staged steps back to a named savepoint without aborting entire transaction.
• agent_2pc_export: Exports an active transaction to a verified portable .a2pc bundle for swarm review.
• agent_2pc_import: Imports a verified .a2pc bundle into this agent coordinator as a prepared transaction.
• agent_2pc_hook_check: Verifies Git workspace integrity by asserting zero uncommitted transactions exist.
• agent_2pc_git_commit: Atomically materializes 2PC transaction and immediately creates a Git commit.
• agent_2pc_compact: Purges finalized transactions from WAL and emits checkpoint marker.
• agent_2pc_status: Inspects active transactions and receipts count.
• agent_2pc_commit: Atomically materializes all staged actions across all tools.
• agent_2pc_abort: Deterministically rolls back all staged work if any step fails.

---

🔒 Optimistic Concurrency Control (OCC) for Multi-Agent Swarms

When multiple autonomous agents or human developers edit the same repository concurrently, agent-2pc prevents lost updates and silent overwrites:

# 1. Agent reads a file and registers OCC fingerprint
agent-2pc record-read --tid "$TID" --path "src/auth.rs"

# 2. If another process modifies src/auth.rs while the agent was planning...
# 3. Phase 1 PREPARE automatically detects hash mismatch and aborts:
# ✖ ABORTED: Conflict detected: file src/auth.rs was modified concurrently

---

🖥️ Live Terminal Monitor & Transaction HUD (top)

Inspect in-flight transactions, WAL disk usage, and recovery health in real-time with continuous auto-refresh:

# Snapshot inspection
agent-2pc monitor

# Or continuous live dashboard (aliased as `top`)
agent-2pc top --watch --interval-ms 500

┌────────────────────────────────────────────────────────────────────────┐
│  ⚡ agent-2pc Live Transaction Monitor & HUD                           │
├────────────────────────────────────────────────────────────────────────┤
│  Workspace      :: .agent-tx                                          │
│  WAL Log        :: 4.2 KB (18 records, CRC32 verified)                │
│  Scratch Dir    :: 0.0 KB in-flight                                   │
│  System State   :: HEALTHY (Durability verified, zero leaks)          │
├────────────────────────────────────────────────────────────────────────┤
│  Transactions: 1 Active  |  12 Committed  |  1 Aborted                 │
└────────────────────────────────────────────────────────────────────────┘

---

🔀 Three-Way Semantic Merge Engine (agent-2pc merge)

When concurrent agents make non-overlapping edits to the same file, agent-2pc reconciles changes automatically rather than aborting:

agent-2pc merge --base ancestor.rs --ours committed.rs --theirs staged.rs --output merged.rs

---

🤖 One-Shot Batch Manifest Execution

AI agent planners can submit an entire multi-step transaction plan as an atomic JSON document:

{
  "timeout_ms": 30000,
  "steps": [
    {
      "participant_id": "fs_route",
      "intent": {
        "type": "fs_write",
        "path": "src/routes/user.rs",
        "content": "// User Route Handlers",
        "create_dirs": true
      }
    },
    {
      "participant_id": "cmd_test",
      "intent": {
        "type": "command",
        "command": "cargo test --test user_test",
        "working_dir": ".",
        "env": {}
      }
    }
  ]
}

agent-2pc run-batch --file manifest.json

If cmd_test fails, src/routes/user.rs is discarded instantly before touching the repository.

---

💻 Client SDKs (Python & TypeScript)

Python SDK (agent-2pc)

from agent_2pc import Agent2PC

tx_client = Agent2PC()

# Automatic transactional context: commits on clean exit, rolls back on exception
with tx_client.transaction(timeout_ms=30000) as session:
    session.stage_write("src/auth.py", "def authenticate(): return True")
    session.stage_cmd("pytest tests/test_auth.py")

TypeScript SDK (agent-2pc)

import { Agent2PC } from "agent-2pc";

const client = new Agent2PC();
const session = await client.begin({ timeoutMs: 30000 });

await session.stageWrite("src/routes.ts", "// Route Handlers");
await session.stageCommand("npm run test");
await session.commit();

---

🛡️ Crash Consistency & Tamper Detection

Every record written to .agent-tx/wal.bin uses binary framing with a 32-bit hardware-accelerated CRC32 checksum:

+----------------+---------------+--------------------+------------------+-----------------------+
|  Magic (4B)    |  Version (1B) |  Payload Len (4B)  |    CRC32 (4B)    |    JSON Payload (NB)  |
|  `0x41325043`  |      `1`      |  Little-Endian u32 |  Little-Endian   |  Serialized Record    |
+----------------+---------------+--------------------+------------------+-----------------------+

If power is lost or the agent process is killed (SIGKILL):

agent-2pc recover

• Transactions with CommitDecision logged are rolled forward to finish execution.
• In-flight uncommitted transactions are rolled back and scratch files are cleaned up.
• Torn writes and bit-flips are trapped via CRC32 validation.

---

🧪 Verification & Test Suite

cargo test

running 57 tests
test test_wal_append_latency_benchmark ... ok
test test_end_to_end_2pc_transaction_throughput ... ok
test test_daemon_in_memory_ipc_throughput ... ok
test test_cluster_coordinator_consensus_evaluation_over_network ... ok
test test_cluster_network_transport_prepare_and_commit ... ok
test test_distributed_consensus_all_prepared ... ok
test test_distributed_consensus_peer_abort ... ok
test test_compactor_offline_compact_path ... ok
test test_crash_recovery_from_compacted_wal ... ok
test test_compaction_preserves_in_flight_transactions ... ok
test test_compaction_purges_committed_and_aborted ... ok
test test_crdt_commutativity ... ok
test test_crdt_deletion_tombstone ... ok
test test_crdt_concurrent_insertion_convergence ... ok
test test_daemon_lifecycle_and_ping ... ok
test test_daemon_transaction_workflow_over_uds ... ok
test test_daemon_concurrent_clients ... ok
test test_bundle_crc32_tamper_detection ... ok
test test_transaction_diff_and_diffstat ... ok
test test_bundle_export_import_and_commit ... ok
test test_bundle_with_multiple_participants ... ok
test test_reconstruct_adapters_extended_coverage ... ok
test test_bundle_path_traversal_prevention ... ok
test test_coordinator_parallel_prepare_panic_resilience ... ok
test test_fs_adapter_directory_and_missing_parent_rejection ... ok
test test_commit_abort_idempotency ... ok
test test_exec_runner_failed_command_does_not_stage_and_reverts ... ok
test test_exec_runner_autostages_new_and_modified_files ... ok
test test_git_hook_installation_and_clean_check ... ok
test test_git_hook_detects_in_flight_transactions ... ok
test test_daemon_reap_ipc_command ... ok
test test_daemon_ttl_reaper_aborts_expired_transactions ... ok
test test_reflink_or_copy_snapshot_staging ... ok
test test_monitor_stats_collection ... ok
test test_wal_framing_and_crc32_tamper_detection ... ok
test test_microvm_adapter_execution ... ok
test test_optimistic_concurrency_conflict_detection ... ok
test test_api_adapter_lease_and_compensation ... ok
test test_crash_recovery_uncommitted_rollback ... ok
test test_sandbox_adapter_filesystem_protection ... ok
test test_2pc_partial_failure_deterministic_rollback ... ok
test test_governor_adapter_clean_execution ... ok
test test_2pc_all_prepared_atomic_commit ... ok
test test_parallel_prepare_with_short_circuit_abort ... ok
test test_governor_adapter_timeout_containment ... ok
test test_mcp_initialize_and_tools_list ... ok
test test_mcp_full_tool_surface_execution ... ok
test test_three_way_merge_overlapping_conflict ... ok
test test_three_way_merge_non_overlapping_clean ... ok
test test_overlay_runner_execution_and_rollback ... ok
test test_web_hud_server_http_and_api ... ok
test test_savepoint_creation_and_isolation ... ok
test test_savepoint_wal_replay_and_crash_recovery ... ok
test test_speculative_execution_and_rollback_to_savepoint ... ok
test test_nested_multiple_savepoints ... ok
test test_wasi_adapter_execution_and_rollback ... ok
test test_expanded_mcp_tools_surface_and_exec ... ok

test result: ok. 58 passed; 0 failed; 0 ignored; finished in 2.65s

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💖 Sponsoring & Supporting Development

agent-2pc is an independent open-source project bringing database-grade ACID two-phase commit and crash-consistent WAL guarantees to autonomous AI coding agents, harnesses, and MCP pipelines.

If agent-2pc protects your workspaces from dirty repository state, broken syntax, or hallucinated LLM rollbacks, consider sponsoring development on GitHub:

• ☕ Backers ($5–$10/mo): Named recognition in release notes and README backer roll.
• ⚡ Power Users & Agent Teams ($25/mo): Direct influence on roadmap RFCs and priority feature development.
• 🏢 Organization Sponsors ($100/mo): Prominent company logo and link displayed on the repository README.

👉 Become a GitHub Sponsor

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📜 License

MIT License. Designed and engineered by Ronit Gupta.