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Head to head · Agent harnesses · October 2026 research run

Emdash vs Letta

Letta scores 59.7 (C) on agent readiness against Emdash's 53.9 (D), and leads in 5 of 7 scored categories. Both do agent harnesses.

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EmdashGeneral Action, Inc. · Agent harness D53.9/100#927 of 1486 LettaLetta · Agent harness C59.7/100#684 of 1486

Which one, for what

Emdash D

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

Also in its favour

  • No key needed to call it

Watch for

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

Letta C

Best for Long-lived coding agents and assistants that keep memory and identity across sessions and machines.

Ahead on

  • Schema & documentation, 70 against 55
  • Agent ergonomics, 67 against 55
  • Maintenance & community, 85 against 70

Also in its favour

  • Runs on your own machine

Watch for

The default permission mode is unrestricted, the renamed bypassPermissions, so tool calls aren't confirmed unless the user picks another mode

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.

Schema & documentation Letta +15

Emdash 55

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

Letta 70

Harness reading. docs.letta.com serves llms.txt and a Markdown version of every page, with an applies_to block saying which backend and interface each page covers (10). TypeScript types for the Agent SDK and a documented App Server WebSocket protocol, but no JSON Schema or OpenAPI for the harness (15 of 25). Pages say when to use local or cloud backends, subagents and channels (14 of 20). Permission modes and options are typed in the SDK (12 of 15). Example applications and a remote client reference (11 of 15). Releases most days but no changelog file (8 of 15). Total 70.

Maintenance & community Letta +15

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.

Letta 85

v0.34.42 on 6 November 2026 (30). Dozens of releases in 90 days (20). Pull requests are merged daily; recent issues from users have few replies (15 of 25). npm and PyPI packages and the Agent SDK track the releases (12 of 15). Lock files, CI and nightly smoke tests (8 of 10). Total 85.

Agent ergonomics Letta +12

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).

Letta 67

Harness reading. Toolsets switch with /model, skills load per agent, and subagents run in the background (18 of 25). Context is managed through memory blocks, reflection and dreaming (12 of 20). letta -p --output-format json for scripted runs and an App Server for programmatic control (12 of 20). Conversations resume by agent and conversation id, and memory is git-tracked so changes can be reverted (15 of 20). Runs with no account on the local backend, with one SDK language, TypeScript (10 of 15). Total 67.

Score by category

CategoryWeight this runEmdashLettaEdge
Reliability16%205558Letta +3
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25570Letta +15
Agent ergonomics13%16.25567Letta +12
Security & auth14%17.53835Emdash +3
Payments & pricing10%12.56060even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87085Letta +15
Transparency & trust7%8.85455Letta +1
Negative events≤1500
TotalD 53.9/100C 59.7/100

Facts side by side

FactEmdashLetta
KindAgent harnessAgent harness
VendorGeneral Action, Inc.Letta
Hosted endpointno (local only)no (local only)
Transportsstdio
AuthNoneOAuth or key
PricingFreeFreemium
x402nono
LicenceApache-2.0Apache-2.0
Read-only variant documentednono
llms.txtnoyes
Last release2026-11-062026-11-06
Terms last updatedno document linkedno date given
Privacy policy last updatedno document linkedno date given
Customer content may train modelsnot read yetnot found in the text
Terms restrict automated accessnot read yetnot found in the text
Terms restrict benchmarkingnot read yetnot found in the text
Terms or service can change without noticenot read yetnot found in the text
Arbitration or class-action waivernot read yetyes
Popularitynone3.8k stars, 86k npm/wk, 2.2k PyPI/wk

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.

Letta

Letta's open-source harness gives agents git-tracked memory blocks, skills, subagents and headless JSON runs, with a $0 plan and public per-agent API prices. It starts in the unrestricted permission mode, defaults to Letta Cloud, sends usage telemetry unless LETTA_CODE_TELEM=0 is set, and the V1 API server the comparisons describe is retired.

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

Letta

  1. Start headless runs with an explicit permission mode such as standard or strict; the default auto-approves tools
  2. Pass --backend local for work that must stay on the machine, since Letta Cloud is the default
  3. Set LETTA_CODE_TELEM=0 in unattended runs if usage events must not be sent
  4. Use letta -p --output-format json for scripted runs and parse the JSON, not the terminal output
  5. Don't plan on the retired V1 REST server or .af AgentFile import; both are gone

Questions

Which is better for AI agents, Emdash or Letta?

Letta scores 59.7 (C) on agent readiness against Emdash's 53.9 (D), and leads in 5 of 7 scored categories.

Are Emdash and Letta open source?

Yes. Emdash is open source (Apache-2.0). Letta is open source (Apache-2.0).

Other comparisons with Emdash or Letta

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