Prism Coder

Give your AI agent memory that lasts — and see the cloud tokens it never had to spend. Persistent sessions, knowledge graphs, offline tool-routing, and an auditable savings meter. Fully local and free.

Prism Coder is an MCP server that gives Claude, Cursor, and other AI tools long-term memory that survives across sessions. It ships with the open-weight prism-coder model fleet (2B–27B) for fast, offline tool-routing — no cloud required. And it keeps score: every call served locally is metered, so prism savings shows the token volume that never reached your cloud model — measured honestly, in tokens.

No account needed. No API keys. Runs on your machine.
A paid subscription adds cloud sync, higher model tiers, and team features through the Synalux portal.

What Prism gives you

• Session memory that survives restarts — resume projects with handoff notes, recent work, open TODOs, and configurable quick, standard, or deep context.
• Local-first inference — bounded work is routed through local Ollama models first, with automatic 2B/4B/9B/27B selection based on installed models, available RAM, context fit, and subscription entitlements.
• A savings meter you can audit — prism savings (or the local_savings tool from any host) reports the token volume local serving kept off your cloud model: headline, local share, per-model breakdown. It reports tokens, never an invented dollar figure, and prints its assumptions and known undercounts inline — a number you can check, not marketing.
• Route-output enforcement — route mode returns only well-formed calls to tools the host actually advertised. Standard and higher plans can add authenticated deterministic correction; route_guard: "local" keeps the prompt and draft entirely on-device.
• One setup for every agent — prism connect configures Claude Code, Claude Desktop, Cursor, Gemini CLI, and Codex while preserving unrelated settings.
• Subscription-aware skills — entitled skills are synchronized before the host launches, with safe upgrades, downgrades, conflict preservation, and offline last-good recovery.
• Hook-free startup — MCP metadata and native instructions request Prism's startup context without requiring lifecycle hooks or a Prism-owned launcher. Where a host offers hooks (Claude Code, Codex), prism connect adds two small ones on top: mid-session prompt routing, and a post-compaction re-injection of the protected-floor digest.
• Safe escalation and observability — inference outcomes are explicit, reserved content remains fail-closed, and local/cloud usage is recorded for review.

Get started

npm install -g prism-mcp-server
prism connect

Use prism connect --dry-run to preview changes, prism connect --all to configure every detected host, or prism connect --refresh to reconcile Prism-managed entries after an upgrade. Restart the host after connecting.

Prism works locally without an account, API key, or cloud subscription. Add a Synalux subscription when you want cloud memory, paid-tier skills, or team features.

After a few sessions, ask what it's been worth:

prism savings --period month

💾 Local serving — LAST 30 DAYS
  ~510K tokens kept off your cloud model
  53 call(s) served locally of 58 routed (91%)

Your numbers will differ — that's the point: it reports what your machine actually served, not a projection. Full report anatomy and the honesty rules behind it are in the local_savings section.

Install as a plugin

Prism also ships as a plugin, which registers the MCP server and the startup skill for you.

Both hosts install straight from this repository. There is nothing to host and no server to run: the catalogue is the .claude-plugin/marketplace.json file committed here, and your client clones it from GitHub.

Claude Code:

claude plugin marketplace add dcostenco/prism-coder
claude plugin install prism-coder@prism

Codex:

codex plugin marketplace add dcostenco/prism-coder
codex plugin add prism-coder@prism

The plugin registers prism-mcp via npx -y prism-mcp-server. If you already configured Prism by hand — prism connect writes an mcp_servers.prism-mcp entry — you have that server twice under one key. Install the plugin or run prism connect, not both.

What prism connect changes about host subagents

connect steers bounded work to prism_infer on your machine rather than to host-spawned agents. What it writes differs per host, and it does not disable subagents everywhere — Claude Code keeps them and is pointed at an economy model instead. Prism's local workers stay available over MCP in every case.

Two things worth knowing:

• experimental is Gemini's namespace, not ours. Prism is not enabling anything experimental — it writes false to a flag Gemini already defines at that path. Writing anywhere else would have no effect.
• That namespace is by definition temporary. If Gemini promotes enableAgents out of experimental, Prism keeps writing the old path, Gemini reads the new one, and host subagents quietly turn back on. Nothing errors and the settings file still looks correct. If you see host subagents running while enableAgents reads false, check whether the key has moved before assuming connect failed to write it.

Both writes are idempotent in the sense that a host already configured this way is left untouched — but they are re-applied on every prism connect run, not only on --refresh. If you deliberately re-enable host subagents, the next connect will turn them off again. Keep them on by not re-running connect, or by re-enabling after each run.

What's New in v20.18.1

Task skills survive compaction and update in place

• Prompt-routed task skills now return after compaction. The hook restores the three most recently active task skills alongside the protected-floor digest, so a short follow-up such as continue keeps the workflow and visual verification rules that governed the work before context was compacted.
• A completed managed-skill sync refreshes active task rules on the next prompt. The hook compares the materialized generation on disk with its per-session state, re-authorizes every restored name against the current manifest, and injects the current bodies. A downgrade clears stale paid task state; Prism-managed directories cannot use the user-owned local-skill exception.
• User-owned local skills now route with their actual body. A local SKILL.md remains usable while signed out, while an entitled platform body takes precedence if both sources use the same name.
• Codex hook context is anchored to the user's request. Routed rules tell the model to execute the preceding user request with the rules applied, avoiding the trailing developer-context placement being mistaken for a new task. The anchor and all restored content share the 9,800-character limit.
• Hook version 5 enforces its command version. A still-running host with a trusted v4 command cannot execute the rewritten v5 script. After upgrading, run prism connect --refresh --no-models; Codex must trust both new v5 hook entries in /hooks. Restart the host if it has not reloaded the new hook definitions. Once v5 is active, later skill-body generations refresh on the next prompt without another host restart.
• State names are validated and bounded before they become CLI arguments, and the two-call refresh paths fit inside the host's 15-second hook timeout.

What's New in v20.18.0

The protected floor rides the bootstrap — and survives compaction

• session_bootstrap now inlines a digest of the protected floor on paid tiers at standard and deep depth: one inert line per rule, derived from each skill's first paragraph (or its pinned digest:), plus its section map, ~5.6K chars for the full floor. Small-context hosts such as Codex were re-reading the sixteen SKILL.md files every session (median 8 re-reads / 36KB, worst 823 / 5.1MB in rollout logs) because the bootstrap only named them. The digest is paid for on top of the context budget, so the ledger/handoff share at every depth is byte-identical to before. Quick depth stays names-only