Foremerge

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Foremerge is the open-source coordination protocol for coding agents, built above Git. Agents keep isolated worktrees while sharing intent, semantic claims, dependencies, provisional ChangeSets, decisions, validation, and provenance.

Tell your agent to install

Done

See collisions before they land

Status:Foremerge0.4.0

is a pre-1.0, local-first MVP. The CLI, JSON API, MCP server, SQLite store, deterministic conflict detector, and verification-gated lifecycle are implemented. Public schemas may still change. Shared multi-machine mode and published benchmark results do not yet exist.

Say you have two AI agents working on the same project at the same time. Each one gets its own copy of the code, so they never fight over files. Both finish. Both look correct. Then you find they undid each other's work.

Git cannot warn you about that, because Git compares text and not intent. It will stop you when two agents edit the same part of the same file. What it cannot see is two edits that are each perfectly reasonable on their own and land in different files. If one agent moves every caller onto a new StripePaymentService

while another adds PayPal support to the old PaymentService

, nothing overlaps, so Git merges both without complaint and the PayPal work is left stranded on a class nothing calls any more.

Foremerge fixes this by having agents announce what they are about to do, before they do it.

Each agent says what it is about to touch. Not the code, just the target, like "I am going to change thesendEmail

function."Every agent reads from one shared list. It is a small database inside your project's.git

folder, so every agent on your machine sees the same picture, whether it is Claude, Codex, or Cursor.If two plans collide, you hear about it right away. Foremerge names the two agents, explains why their plans clash, and suggests how to split the work. Both worktrees are still clean at that point, so no work has to be thrown away.

Think of it as a shared whiteboard. Before an agent starts, it writes down what it is about to work on, and it reads what everyone else already wrote.

Two things Foremerge deliberately does not do. It never locks a file or blocks an agent, because a single crashed agent would then stall the whole fleet, so the warnings are advisory and you stay in charge. And it never asks a model to judge conflicts, so the same inputs always produce the same answer.

Agent A: Replace PaymentService with StripePaymentService
Agent B: Add PayPal support to PaymentService

These agents can work in different trees without touching the same line. The plans still collide: one removes the extension point while the other depends on it.

Both agents declare the same symbol:PaymentService

scope, one saying it will replace

it and the other that it will extend

it. Foremerge compares those two declarations before either writes code, raises a HIGH

advisory, and suggests coordinating on a stable abstraction such as PaymentProvider

. That suggestion is explainable evidence, not an automatic architecture decision or a hard lock.

Because the operation is declared rather than read out of the summary, it does not matter how either agent phrased its plan. "Consolidate payments onto Stripe" and "Replace PaymentService with Stripe" reach the same verdict.

Git remains the durable repository. Foremerge supplies the missing shared awareness above it.

Rendered from the actual conflict fields captured by the 0.1.0 release-binary run in examples/terminal-session.txt. The displayed command uses the shown jq filter; output is abridged for readability.

Paste this into Claude Code, Codex, or Cursor from inside the repository you want to coordinate:

Set up Foremerge in this repository so we can coordinate parallel agents.

1. Install it:      curl -fsSL https://foremerge.com/install.sh | sh
2. Initialize:      foremerge init
3. Wire this client and any others in use: foremerge setup all
4. Register the check I should be validated against, for example:
                    foremerge checks set test -- cargo test --all-targets
5. Confirm:         foremerge doctor --client all

Then read the Foremerge skill that step 3 installed for this client and follow
it from now on: publish your intent with semantic scopes before editing, claim
the scope, and check for conflicts before you start.

Adjust step 4 to whatever this repository's real test command is. Step 3 asks the client to enable an MCP server, so it will prompt you before doing so. The Codex registration is user level, but one registration serves every repository: start Codex inside the repository you want it to coordinate.

You need a recent Git and jq

. Install a prebuilt, checksum-verified release binary (macOS and Linux; the script installs to ~/.local/bin

):

curl -fsSL https://foremerge.com/install.sh | sh

Tip

Two commands, one program. This installs foremerge

and fmg

, the same binary under a shorter name, so fmg status

and foremerge status

do the same thing. Examples below spell out foremerge

; type whichever you prefer.

Or build from source with Rust 1.85+: cargo install --locked --git https://github.com/naw103/foremerge foremerge

, or cargo install --locked --path .

from a checkout. Windows binaries are on the releases page. To update, re-run the installer. Then, inside the repository you want to coordinate:

foremerge init
foremerge doctor

The installer, the release archives and cargo install

all carry both names from 0.4.0 onward. If something else on your PATH already answers to fmg

, the installer leaves it alone and says so rather than shadowing it.

Install the native skill and MCP entry for any clients used in this repository, then define the trusted checks agents may request by name:

foremerge setup all
foremerge checks set test -- cargo test --all-targets
foremerge doctor --client all

Acceptance is verification-gated: Foremerge runs the check itself rather than taking an agent's word for it. Pick a check that is fast and that would actually catch a broken handoff, such as a build or a typecheck, rather than a full CI suite; this gate decides whether other agents may treat the work as done, and it does not replace CI. If this repository has nothing meaningful to verify, say so once rather than registering a check that always passes:

foremerge checks policy advisory

Work accepted that way is recorded as UNVERIFIED

with the reason, so the audit trail never implies a check ran when none did. foremerge doctor

reports whether the registered checks can actually run here, which matters in agent worktrees, because dependency directories are usually gitignored and git worktree add

will not create them.

Use setup codex

, setup claude

, or setup cursor

for one client. Setup preserves unrelated configuration (including key order in project MCP JSON). Upgrading Foremerge refreshes its own unedited skill file in place, but a skill file you edited, or a differing Foremerge MCP entry, is never replaced unless you explicitly pass --force

. setup all

attempts every client and reports each result, exiting nonzero if any failed. The Codex MCP registration is user-level and serves every repository, resolved from the directory Codex is started in; see agent client setup.

init

creates local coordination state under the repository's Git common directory. It does not change tracked files. The following no-worktree sessions are enough to exercise pre-code detection; real coding agents should register their isolated worktrees and actual model identifiers.

STRIPE_AGENT=$(
  foremerge --json agent register \
    --name stripe-agent \
    --no-worktree |
  jq -er '.data.id'
)

STRIPE_RESULT=$(
  foremerge --json intent publish \
    --agent "$STRIPE_AGENT" \
    --task "modernize-payments" \
    --summary "Replace PaymentService with StripePaymentService" \
    --scope symbol:PaymentService=replace
)
STRIPE_INTENT=$(printf '%s\n' "$STRIPE_RESULT" | jq -er '.data.intent.id')

PAYPAL_AGENT=$(
  foremerge --json agent register \
    --name paypal-agent \
    --no-worktree |
  jq -er '.data.id'
)

PAYPAL_RESULT=$(
  foremerge --json intent publish \
    --agent "$PAYPAL_AGENT" \
    --task "add-paypal" \
    --summary "Add PayPal support to PaymentService" \
    --scope symbol:PaymentService=extend
)
PAYPAL_INTENT=$(printf '%s\n' "$PAYPAL_RESULT" | jq -er '.data.intent.id')

printf '%s\n' "$PAYPAL_RESULT" |
  jq '.data.conflicts[] | {kind, severity, scope, explanation, suggestion}'

printf '%s\n' "$PAYPAL_RESULT" |
  jq '.data.related_work[] | {agent, summary, asserted, overlap}'

The first command prints the live finding from your local run. The second prints related_work

: the other agent's intent and every overlapping scope with both declared operations. Foremerge states what overlaps; you decide what it means and record that with foremerge assess record

. No files need to change first. Inspect the captured, clearly labeled transcript in examples/terminal-session.txt.

Claims add ownership context without blocking either agent:

foremerge --json work claim \
  --agent "$STRIPE_AGENT" \
  --intent "$STRIPE_INTENT" \
  --scope symbol:PaymentService \
  --reason "Changing the provider boundary" >/dev/null

foremerge --json work claim \
  --agent "$PAYPAL_AGENT" \
  --intent "$PAYPAL_INTENT" \
  --scope symbol:PaymentService \
  --reason "Adding another provider" |
  jq '.data | {advisory_only, warnings}'

foremerge --json work query --scope symbol:PaymentService |
  jq '.data[] | {agent: .agent.name, intent: .intent.summary, open_conflicts}'

Both claims succeed. The second response includes an overlap warning because a claim is a leased advisory, never exclusive ownership.

  coding agent A                                  coding agent B
        |                                               |
  isolated worktree A                            isolated worktree B
        |                                               |
        +--------- semantic events, not edits ----------+
                              |
                    CLI / MCP / JSON API
                              |
                     Foremerge service
                    /        |        \
       SQLite coordination   git CLI   validation argv
       in <git-common-dir>       |           |
                    \         Git repository /
                     durable commits and refs

Every frontend uses the same service and store. The semantic graph is:

Agent → Task → Intent → Claim → Symbol → Dependency
      → ChangeSet → Test → Result → Decision → Provenance

Mutations update typed SQLite projections, materialize graph edges, and append a hash-chained semantic event in one transaction. The log is useful tamper evidence; it is not a remote identity signature or distributed consensus.

Foremerge resolves the Git common directory and stores its default database at:

<git-common-dir>/foremerge/state.sqlite3

Linked worktrees share that common directory even though their checked-out files are separate. Create a worktree with Foremerge's thin wrapper around stock Git:

foremerge worktree create \
  --branch agent/paypal \
  --path ../payments-paypal \
  --base HEAD

foremerge --cwd ../payments-paypal --json agent register \
  --name paypal-agent \
  --model "$ACTUAL_MODEL_ID"

Another worktree in the same repository sees the registered agent and its intents immediately. You can override storage with --database PATH

or FOREMERGE_DB

, but every local agent must point at the same database to share state. The MVP does not replicate SQLite across machines; do not infer distributed safety from a network-mounted database.

Foremerge snapshots Git state for ChangeSet fingerprints and accepted refs. It does not automatically merge, rebase, cherry-pick, push, or update a target branch.

INTENT ─claim→ CLAIMED ─start→ IN_PROGRESS ─publish→ PROVISIONAL
       ─validate current fingerprint→ VALIDATED
       ─accept gates→ ACCEPTED ─record Git ref→ COMMITTED

Supported scope kinds are:

symbol api schema config infra test migration env file component contract domain

Publish the narrowest useful semantic scope. File paths alone miss API, configuration, schema, infrastructure, and cross-language collisions.

Common commands:

Boundary	Command
Register provenance	`foremerge agent register --name NAME --model MODEL`
Publish intent	`foremerge intent publish --agent ID --task TASK --summary TEXT --scope KIND:KEY=OPERATION`
Claim scope	`foremerge work claim --agent ID --intent ID --scope KIND:KEY`
Start implementation	`foremerge work start INTENT_ID --agent AGENT_ID`
Ask who is changing it	`foremerge work query --scope KIND:KEY`
See what every agent is doing	`foremerge status`
Preflight a plan	`foremerge conflicts check --intent TEXT --scope KIND:KEY=OPERATION`
Record what you concluded	`foremerge assess record --agent ID --intent ID --related-intent-id ID --verdict V --rationale TEXT --action A`
Send coordination	`foremerge coordinate send --from ID --to ID --message TEXT`
Watch semantic events	`foremerge work watch --after-seq 0`

Run foremerge <command> --help

for the complete current flags. Global flags such as --json

, --cwd

, and --database

may appear before or after subcommands.

A ChangeSet captures the agent/model, task and intent, affected files/symbols/contracts, dependencies, implementation summary, reported tests, decisions, provenance, worktree, fingerprint, status, and Git ref. The accepted candidate and its later landing commit are retained separately as accepted_commit

and integration_commit

.

The honest integration order is:

Publish intent, claim semantic scope, and mark implementation in progress.
Work and commit on the isolated agent branch.
Publish a ChangeSet for that clean candidate.
Ask Foremerge to execute validation against its exact fingerprint.
Resolve high conflicts, then accept the still-clean, still-validated ref.
Integrate with ordinary Git or a pull request.
Record the durable integration commit in Foremerge.

foremerge work claim \
  --agent "$AGENT_ID" \
  --intent "$INTENT_ID" \
  --scope component:payments
foremerge work start "$INTENT_ID" --agent "$AGENT_ID"

CHANGESET_ID=$(
  foremerge --json changeset publish \
    --agent "$AGENT_ID" \
    --intent "$INTENT_ID" \
    --summary "Introduce PaymentProvider and StripePaymentProvider" \
    --file src/payments.rs \
    --symbol PaymentProvider \
    --symbol StripePaymentProvider \
    --contract payment-provider \
    --provenance-json '{"source":"coding-agent"}' \
    --git-ref HEAD \
    --worktree "$PWD" |
  jq -er '.data.id'
)

foremerge changeset validate "$CHANGESET_ID" \
  --worktree "$PWD" \
  -- cargo test --all-targets

foremerge changeset accept "$CHANGESET_ID" --git-ref HEAD

foremerge changeset commit "$CHANGESET_ID" --git-ref main

Agent-reported --reported-test COMMAND=STATUS

values are provenance only. They do not satisfy acceptance. Foremerge-owned validation records the command argument vector, exit status, output, duration, and candidate fingerprint. Any detected change after validation makes that attempt non-authoritative, but its output and changed-path diagnostic remain queryable with changeset attempts

.

For trusted checks that generate disposable untracked output, an operator may set exact or directory-prefix rules without changing tracked files:

foremerge validation-exclusions set \
  --path coverage.log \
  --path target/validation-reports/

The normalized policy digest is part of the candidate fingerprint, tracked changes are never excludable, MCP cannot change the policy, and generated files must still be removed before acceptance. See ADR 0001.

Acceptance also requires a clean worktree and no unresolved HIGH

conflict, unless the caller deliberately uses the visible --allow-high-conflicts

override together with --override-reason "..."

. Prefer resolving a conflict with an explicit rationale. Acceptance creates refs/foremerge/accepted/<changeset-id>

; it does not merge code.

Validation commands run as trusted local code with your operating-system permissions. Foremerge does not sandbox them.

Run foremerge mcp

over stdio. MCP does not require the HTTP daemon; both are adapters over the same database.

Tool	Purpose
`register_agent`
Record agent, model, capabilities, and worktree provenance
`publish_intent`
Announce planned work, declare what it does to each scope, and receive conflicts plus related work to assess
`record_assessment`
Record what you concluded about one related intent and what you will do
`claim_work`
Create leased advisory claims on semantic scopes
`query_work`
Find agents, intents, claims, ChangeSets, and conflicts
`check_conflicts`
Check a published or provisional intent before code changes
`publish_changeset`
Record implementation, tests, decisions, and Git provenance
`coordinate_with_agent`
Send a durable message linked to a conflict or ChangeSet
`start_work`
Advance claimed work into implementation
`resolve_conflict`
Record an audited resolution for a durable conflict
`run_verification`
Run a trusted repository check by name, never raw MCP argv
`accept_changeset`
Apply final conflict, dependency, validation, and Git gates
`record_commit`
Record the actual Git integration commit
`discard_work`
Preserve abandoned work while releasing claims and blockers
`list_agents`
Read registered agent provenance
`get_intent`
Read one intent and current conflict snapshot
`get_changeset`
Read one ChangeSet and Git/provenance state
`status`
Read one consistent coordinator status snapshot

Start from the valid minimal config in examples/mcp-config.json. It assumes the client launches

foremerge

with the repository as its working directory. Clients without a repository working-directory setting should pass an absolute --database

before mcp

; derive the Git common directory instead of assuming that a linked worktree's .git

is a directory.See agent client setup for the installer, native skill locations, client-specific MCP files, diagnostics, and safe replacement rules. See MCP setup for transport behavior, schemas, named checks, example inputs, and multi-worktree configuration.

Source clones include equivalent skills in .codex/skills

, .claude/skills

, and .cursor/skills

, plus portable Claude and Cursor MCP templates. A Cargo installation embeds the canonical skill so foremerge setup

can install it into another repository without copying this source tree.

The daemon defaults to authenticated loopback HTTP on http://127.0.0.1:47811

. init

creates a bearer token with private file permissions where the platform supports them.

In one terminal:

foremerge daemon

In another terminal, read the token path from Foremerge rather than guessing it:

export FOREMERGE_URL=http://127.0.0.1:47811
TOKEN_FILE=$(foremerge --json init | jq -er '.data.token_file')
FOREMERGE_TOKEN=$(tr -d '\r\n' < "$TOKEN_FILE")

curl --fail --silent --show-error \
  --header "Authorization: Bearer $FOREMERGE_TOKEN" \
  --get "$FOREMERGE_URL/v1/work" \
  --data-urlencode 'scope=symbol:PaymentService' |
  jq .

Do not print, commit, or share the token. /healthz

is database-free process liveness and /readyz

is a bounded non-waiting store probe; both are public. Every /v1

route, including the paged event-chain audit, requires the token unless the daemon was deliberately started with --no-auth

for a trusted local test. The MVP refuses non-loopback binds and is not a hardened multi-tenant service.

The CLI escape hatch foremerge request

reads local auth automatically. A runnable curl walkthrough is in examples/api-requests.sh; the full route and error reference is

JSON API.

Conflict detection is deterministic and explainable, but heuristic. It can miss synonymous concepts and warn on compatible work.
Claims warn; they never lock files, symbols, or agents.
Passing validation proves only that the recorded command passed for the recorded fingerprint, not that the test plan was complete.
Git refs and process results are stronger evidence than self-reported model, prompt, or test prose.
The event chain detects changes inside the retained chain; it is not a signature, remote attestation, or external checkpoint.
Local SQLite is not shared-mode consensus, and the loopback bearer token is not a public deployment security model.
There are executable benchmark fixtures, a reproducible query harness, and a benchmark plan, but no published coordinated-vs-uncoordinated performance results yet.
Foremerge does not replace code review, architecture ownership, CI, security scanning, Git hosting rules, or backups.

Read the complete limitations and trust model before using Foremerge as an integration gate.

Document	What it answers

Protocol State model Conflict detection Git integration Agent clients MCP setup JSON API OpenAPI schema Benchmark plan Validation exclusion ADR Roadmap Limitations BrandAlso see the changelog, security policy, and code of conduct.

Contributions are welcome, especially protocol feedback on scope vocabulary, conflict evidence, ChangeSet provenance, and verification policy. Read CONTRIBUTING.md, then run the complete local gate:

make verify

Foremerge is licensed under the Apache License 2.0.

source & further reading

github.com — original article Show HN: AI Shipcheck – know if your AI-built app is ready to ship Show HN: Agentctl – Terraform for your agent harnesses Spotify Backstage Meet LiteLLM for Corporate AI Governance

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