Letta vs Parallax

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.

Parallax 29

The review API has no OpenAPI or endpoint reference. Endpoints appear only in curl examples, and the base URL $PARALLAX_URL is not published (0). conifer.build/llms.txt covers the gateway in detail and Parallax in two lines that point to the docs (5). The docs explain sessions, sweeps, evidence states, memory and retention at length, but nothing documents the app, Captain, fallback or fast merge (8). parallax.yml keys are listed with allowed values (deliver: proven-only, review: off, severity floors, sweep modes), but request and response shapes for the API are not (5). curl examples, sample sweep lines and a table of skip reasons with the fix for each (8). Paths sit under /v1, with no changelog for Parallax (3).

Letta 60

No x402, MPP or L402 (0 of 40). Per-unit API prices are public, $0.10 per active agent a month and $0.00015 a second of tool execution, plus plan prices (20). A $0 plan with bring-your-own keys; no card is mentioned (20). The CLI runs locally without signing in (20). Total 60.

Parallax 30

No x402, MPP or L402 (0). Parallax episode credit prices are read from the account after sign-in. Gateway token prices are public at GET /v1/catalog with no key, which covers Conifer credit spent by agents (10). $50 of Conifer credit and 5 free episodes on GitHub sign-up, with no card mentioned, and agents can run on the owner's own Claude and Codex subscriptions (20). A person has to download the app, sign in and install the GitHub App, so no autonomous onboarding (0).

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.

Parallax 56

v1.0.2 on 16 October 2026 (30). Three releases, v1.0.0 to v1.0.2, on 15 and 16 October 2026 (20). Closed service. No public changelog. Support through a GitHub issues link, a Discord server and email, none of which we could check for replies (3). No Parallax SDK and nothing in the MCP registry. Conifer's SDK is for the gateway (0). Signed builds with checksums and a self-updater, with no CI to inspect (3).

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.

Parallax 42

Scored on the review API and the hooks, the only parts an agent touches. The session-start brief is cut at 6,000 characters, memory per review call at 12,000, and lesson_cap sets 1 to 20 lessons per person (8). repo filters on recall and brief, brain=true on the ledger, no documented pagination (4). Skip reasons such as capture_commit_missing and test_configuration_missing each come with a fix, but HTTP error codes for the API are not documented (12). A session is swept once per capture mark, retries use no extra credit, and a fix PR is reused and never reopened or merged by Parallax (14). No SDK for Parallax, and capture of every repository is the default (4).

Letta 58

Local-software lines, read for the harness. @letta-ai/letta-code on npm with Node.js 22.19 or newer, and PyPI wheels for glibc Linux, macOS 14 and Windows x64 with Python 3.9 or newer stated (20). ci.yml, nightly update smoke tests and Telegram live smoke tests exist, but GitHub's API answered with a rate limit, so run results were unread (15 of 25, unchecked). 332 open issues and pull requests, mostly pull requests; recent bug reports such as recall reading the wrong conversation have no reply yet (15 of 25). 398 tags at 0.34.x with release notes on GitHub, no changelog file, and breaking removals such as AgentFile announced in the README (8 of 15). Pre-1.0 (0). Total 58.

Parallax 40

Read as local software, because the launched product is the app the owner runs. A signed and notarised universal DMG for macOS 12 or later and Linux tarballs for x86-64 and arm64 on GitHub Releases, with SHA256SUMS and an install script. No package registry (20). The release repository holds a README and binaries only, with no public CI or tests (0). We could not read its issues, because our GitHub access refused the issue pages, so the issue record is unchecked and scored absent (0). Semver tags v1.0.0 to v1.0.2, but no release notes or changelog we could read (5). Version 1.0.2 (15). The hosted review service has no status page and no published rate limits. conifer.build/uptime covers upstream model providers only.

Letta 35

Harness reading of the framework checklist, as for the other harnesses. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for injection posture, 15 for audit and 20 for the security programme. Letta Cloud is the default backend, so agent state and conversations go to Letta's servers, and telemetry is on by default (10 of 30). The default permission mode is unrestricted; standard, acceptEdits and strict are opt-in, and cloud sandboxes exist for remote work (4 of 20). No prompt-injection guidance found for fetched pages or channel messages (5 of 15). Conversation search and git history of memory give an operator a record of what the agent saw and changed (10 of 15). SECURITY.md routes reports to support@letta.com and scopes out the retired server; no security.txt, bounty or certification found (6 of 20). Total 35.

Parallax 43

Harness reading of the framework checklist, as for the other harnesses. 30 for what leaves the machine by default, 20 for approvals and sandboxing, 15 for prompt-injection posture, 15 for audit and 20 for the security programme. Once installed, capture uploads transcripts, tool calls with results and source snapshots from every repository on the machine unless a local allowlist is set first, and the app updates itself by default. Uploads stop with PARALLAX_STORE_UPLOAD=off and the token is revocable (8). Proofs run in a throwaway cloud copy, automatic PR review is off by default and Parallax never merges its own fix PR. What Captain may do to a running agent is not documented (10). Reviewers read untrusted transcripts and code with no documented mitigation. Lessons injected into the agent come only from verified outcomes and maintainer replies, never bots, and the brief labels everything else as cited fact (8). Recall receipts, per-injection records, sweep lines, the review ledger and GET /v1/calibration (12). No security.txt, bug bounty, SOC 2 or advisories. The privacy policy names a contact for security reports with a two-business-day reply and lists encryption and row-level security (5).