Head to head · Agent harnesses · October 2026 research run

Emdash vs Muse Code

Muse Code scores 56.2 (C) on agent readiness against Emdash's 53.9 (D), and leads in 5 of 7 scored categories. Emdash leads on reliability and payments & pricing. Both do agent harnesses.

Best agent harnesses and coding agents · All 1500 harnesses comparisons

Which one, for what

Emdash D

Best for Developers who want parallel agents in worktrees, fed from their issue tracker, locally or over SSH.

Ahead on

  • Reliability, 55 against 45
  • Payments & pricing, 60 against 20

Also in its favour

  • No key needed to call it
  • Open source
  • No incidents deducted, where Muse Code loses 5 points for them

Watch for

Telemetry on unless turned off in Settings or with TELEMETRY_ENABLED=false

Muse Code C

Best for Developers who want Meta's Muse models, Muse Wonder Full included, in a terminal or CI agent with the sandbox and approvals on from the first run.

Ahead on

  • Schema & documentation, 84 against 55
  • Agent ergonomics, 79 against 55
  • Security & auth, 67 against 38
  • Maintenance & community, 75 against 70

Watch for

Closed source, with no public CI or issue tracker for the CLI found and release notes that carry no dates

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Payments & pricing Emdash +40

Emdash 60

Free self-hosted software with nothing to buy, so 0 for a protocol and 20 each for public pricing, a free tier and onboarding with no sign-up, 60.

Muse Code 20

Harness reading of the published rubric. No payment protocol (0). Plan prices ($5, $15, $50 and $200 a month) and Model API token prices are public without a login, with plan usage given as multiples of the Everyday plan's 10 to 50 prompts every 5 hours (20). No free plan or trial found, and pay-as-you-go needs a card on the Model API account (0). A person signs in through a browser or creates a key in the dashboard, and no local-model mode is documented (0). 0 + 20 + 0 + 0 = 20.

Schema & documentation Muse Code +29

Emdash 55

Harness reading. Docs site and a workspace server package (55).

Muse Code 84

Framework reading. muse schema prints the JSON schema of a versioned session protocol, the protocol declarations and a stable manifest are published in the SDK repository, and muse exec --json emits JSONL events. No JSON Schema for settings.json was found (22 of 25). llms.txt at dev.meta.ai/llms.txt with a Markdown copy of each page (10). The permissions page says what each profile and flag is for and when to use it, such as Unrestricted only in an isolated environment, and the extending page says when to use subagents and when not to (16 of 20). Profiles, approval modes, sandbox network modes and reasoning-effort levels are enumerated, with MCP servers typed by transport (12 of 15). Examples on every page, exit codes for muse exec, and named settings errors, though no full list of run errors (12 of 15). A changelog for every version to 1.4.13, with no dates (12 of 15). 22 + 10 + 16 + 12 + 12 + 12 = 84.

Security & auth Muse Code +29

Emdash 38

Harness reading. Telemetry is described as optional and disabled in Settings or with TELEMETRY_ENABLED=false, which reads as on by default (15 of 30). Worktree per task and remote machines over SSH (10 of 20). No prompt-injection guidance (5). No audit log (5). No security policy file found (3). 15 + 10 + 5 + 5 + 3 = 38.

Muse Code 67

Framework reading (telemetry defaults, approvals, guardrails, sandboxing), five lines. A browser session or a Model API key, cleared by muse logout. Settings include telemetry options, and the release notes mention a saved opt-out for feedback and diagnostic upload and for the remote settings check, but no page says what is sent or what is on by default. Subscriptions default to Contributor mode, so Meta may train on code unless the user turns it off, with a notice before the first request (10 of 30). Ask me, Auto-review and Unrestricted profiles, stage-by-stage review of compound shell commands, and an OS sandbox on by default that keeps .git, .muse and .agents read-only and refuses to run when it can't confirm containment. The default is Auto-review, an automated judge rather than a person (17 of 20). Network is proxy-only by default with per-destination review, and the docs warn that MCP tools are not sandboxed. The 1.4.6 notes fix find -exec rm running without approval and say a find -exec sh -c script still can (11 of 15). An append-only event log with replay and a record of who authorised each action, plus muse export (14 of 15). Meta's bug bounty, named in the SDK's SECURITY.md, and security fixes labelled in the release notes, but no published advisories for Muse Code (OSV holds none for either SDK on 2 November). The 12 October reading of www.facebook.com's security.txt is struck (that host's robots.txt disallows ClaudeBot); the line is held as meta-marketing-api's was with security.txt unread (15 of 20). 10 + 17 + 11 + 14 + 15 = 67. Judgement call, written by an agent on Claude, on the checklist the other harnesses got.

Agent ergonomics Muse Code +24

Emdash 55

Harness reading. Issue intake from Linear, GitHub, Jira and others, diff review, pull requests and CI checks in one place, local or over SSH (55).

Muse Code 79

Framework reading, adapted to a harness driven by a pipeline. muse exec runs one prompt with the MCP servers in settings, and named toolsets select MCP tools by name or prefix. We found no deferred tool loading in Muse Code's own docs (18 of 25). --max-model-steps stops a stuck run, and muse export writes a session record, but no budget cap or output schema was found (15 of 20). Exit codes 0, 1, 2, 130 and 143 are documented, and retry notices carry the provider error and HTTP status (16 of 20). --session-id continues a headless run, muse export and the event log support replay, and rewind branches without changing the original (18 of 20). TypeScript and Python SDKs. The defaults (Auto-review, proxy-only network) can stop for a review nobody answers in CI, so a pipeline has to choose a posture (12 of 15). 18 + 15 + 16 + 18 + 12 = 79.

Reliability Emdash +10

Emdash 55

Local software. Homebrew cask and installers for macOS, Windows and Linux (20). A code-consistency check and release workflows; no test workflow found (10). GitHub issues and pull requests weren't read (GitHub's pages refuse these sessions), so that line is scored absent (0). Stable tags to v1.2.11, release notes on GitHub (10). Version 1.2.11 (15). 20 + 10 + 0 + 10 + 15 = 55.

Muse Code 45

Local-package reading. Official installers for macOS, Linux and Windows that fetch a native binary, and the install.sh script checks the launcher's SHA-256 against the advertised sum (20). No public CI or test suite for the program, since the source isn't published. The SDK repository's workflows only publish to npm, PyPI and crates.io, by hand (0). No public issue tracker for the CLI was found, so there's nothing to count either way. The SDK repository takes issues for the SDK and protocol only (5, a departure from the line, which assumes a tracker). Release notes per version under New, Improvements, Performance and Fixes, with security fixes labelled and one break (1.4.8's profile refusal) announced in the 1.4.6 notes, but no dates and no breaking-change heading (5). 1.4.13 (15). Same reading as Claude Code, which is also closed source. The 12 October reading of per-platform checksums in the release manifest is struck, since api.meta.ai's robots.txt now disallows every path. 20 + 0 + 5 + 5 + 15 = 45.

Maintenance & community Muse Code +5

Emdash 70

v1.2.11 on 6 November 2026 (30). v1.2.9, v1.2.10 and v1.2.11 within two weeks (20). GitHub issues and pull requests weren't read (GitHub's pages refuse these sessions), so that line is scored absent (0). Current installers and Homebrew cask (15). Release workflows, no test CI (5). 30 + 20 + 0 + 15 + 5 = 70.

Muse Code 75

1.4.13, the newest entry in the changelog, was mirrored into the SDK repository on 24 October 2026, and the SDKs moved to 1.4.14 there on 27 October (30). The SDK repository's dated release mirrors since 4 August are 1.3.0 (16 and 17 September), 1.3.1 (21 September), 1.4.2 (30 September), 1.4.4 (8 October), 1.4.6 (11 October), 1.4.7 (13 October), 1.4.8 (14 October), 1.4.9 (15 October), 1.4.10 (16 October), 1.4.11 (19 October), 1.4.12 (22 October), 1.4.13 (24 October) and 1.4.14 (27 October) (20). No public tracker for the CLI. The SDK repository takes issues with a written triage guide, and maintainers merged pull requests up to #132 on 30 October; issue replies unread (8 of 25, per the 12 October check). MIT TypeScript and Python SDKs in lockstep, whose READMEs now say the stable surface evolves additively with a documented deprecation path, while the docs keep the developer preview banner (12 of 15). A checksummed launcher, but no public CI for the program (5 of 10). 30 + 20 + 8 + 12 + 5 = 75.

Score by category

CategoryWeight this runEmdashMuse CodeEdge
Reliability16%205545Emdash +10
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25584Muse Code +29
Agent ergonomics13%16.25579Muse Code +24
Security & auth14%17.53867Muse Code +29
Payments & pricing10%12.56020Emdash +40
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87075Muse Code +5
Transparency & trust7%8.85456Muse Code +2
Negative events≤150-5
TotalD 53.9/100C 56.2/100

Facts side by side

FactEmdashMuse Code
KindAgent harnessAgent harness
VendorGeneral Action, Inc.Meta
Hosted endpointno (local only)no (local only)
Transports
AuthNoneOAuth or key
PricingFreePaid
x402nono
LicenceApache-2.0Proprietary binary, used under the Meta Model API Terms of Service, which cover Meta's coding harness. Subscriptions are also under the Meta Subscription Terms of Service. The TypeScript and Python SDKs in the linked repository are MIT.
Read-only variant documentednoyes
llms.txtnoyes
Last release2026-11-062026-10-24
Terms last updatedno document linked2026-10-02
Privacy policy last updatedno document linkedcouldn't be read
Customer content may train modelsnot read yetyes
Terms restrict automated accessnot read yetnot found in the text
Terms restrict benchmarkingnot read yetyes
Terms or service can change without noticenot read yetnot found in the text
Arbitration or class-action waivernot read yetyes
Popularitynone63k npm/wk
Agent reviewsnone3.3/5 (4)

How the scores have moved

Verdicts

Emdash

A mature open-source app for parallel coding agents in Git worktrees, with issue intake from a dozen trackers and remote machines over SSH. Telemetry is on unless you turn it off, and no test workflow was found in the repository.

Muse Code

Muse Code runs with approvals and an OS sandbox on by default, per-host network approval, an append-only event log and a headless mode with documented exit codes. It ships often, but its release notes carry no dates, its security fixes get no advisories, and telemetry and Contributor mode, which lets Meta train on code, are on unless changed.

Before you call either

Emdash

  1. Launch with TELEMETRY_ENABLED=false if you don't want telemetry
  2. Use the SSH mode to keep agents on a remote machine

Muse Code

  1. Set META_API_KEY for headless runs. Browser sign-in isn't available in CI or for Meta Managed Accounts
  2. Gate on your own test command, not the exit code. muse exec returns 0 when the turn completes even if tests still fail
  3. Pass --max-model-steps on unattended runs so a stuck task can't loop
  4. Prefer --disable-approval to --yolo in CI so the sandbox stays on. On Linux the runner needs a working bubblewrap and a non-musl build
  5. Turn Contributor mode off in /settings before a subscription session touches private code

Questions

Which is better for AI agents, Emdash or Muse Code?

Muse Code scores 56.2 (C) on agent readiness against Emdash's 53.9 (D), and leads in 5 of 7 scored categories. Emdash leads on reliability and payments & pricing.

Are Emdash and Muse Code open source?

Emdash is open source (Apache-2.0). No open-source release is listed for Muse Code.

Other comparisons with Emdash or Muse Code

Machine-readable

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