stack/docs/prd/mosaic-stack.md

PRD: Mosaic Stack

• Status: approved, version 1.2. Jason approved draft 0.4 unchanged as 1.0 on 2026-10-05 (lead decision 61). He approved version 1.1, the Organization requirements, in decision 03130d08-ddce-480d-a601-e59f64744fc3 on 2026-10-14. He approved version 1.2, the chief of staff, the assistant, threads and agent limits, through Mos on 2026-10-14 (lead decisions 141 and 142). It is never edited in place. Changes are a new version.
• Version 1.2 source, Jason's words relayed by Mos:
  • Q147 (full text in lead decision 141): "COS should focus on COS duties. This will include hire/terminate authority for agents, org structure, etc. ... This necessitates the creation of a new role for user interaction. ... The user should be allowed to have 1 - N sessions with this agent to allow for topics of focus in a given thread. ... The interaction agent in each session is the user's main agent."
  • Q148, Mos's read-back of Q147: "Q148: Yes".
  • Q149, on the 1.2 draft: "approved as long as the agent limits are tunable via "Settings" in the WebUI and via the CLI tooling."
  • Q150: "No hard cap on agent limits. All tunable." The five kinds of limit are quoted under Launching.
  • Q151, Mos's read-back of Q150, with the default that launches over a limit are refused and logged and a run that hits its token limit is stopped: "Q151: yes".
• Owner: Jason. Sage writes it from the PRDY interview.
• Template: PRDY "software" (v1/packages/prdy/src/templates.ts), filled by hand until PRDY is ported.
• Interview record: Sage's thread 1ef1e4f8. Round 1 is lead decision 45. Round 2 is lead decision 48. Round 3 is lead decision 53. Design inputs are lead decisions 43, 44, 46, 47 and 49 to 52.

Introduction

Objective

The working north star, ratified as lead decision 44: "Jason declares businesses, projects and roles. Agents in those roles carry the work end to end under declared policy, and only gated decisions reach him."

Context

See docs/plans/2026-10-04_foundation-direction.md. Agents already do real work here. But a person has to launch them, relay between them, hand them credentials and correct them. Jason has no CLI and no complete WebUI, and outstanding decisions don't collect anywhere.

Users

For now the only user is Jason. The stack must still be installable by outside users later, which means:

• an installer;
• no paths or names specific to Jason;
• configuration through the variable layers.

(Round 1, answer D.)

Problem statement

In priority order (round 1):

1. Admin falls on Jason. He launches agents, relays between them, finds credentials and corrects them.
2. Jason can't see what the agents are doing or what's waiting on him.
3. Agents drift from what the business needs. Nothing ties a piece of work to a stated goal.

Scope and non-goals

Hard limits

The stack doesn't do any of these. Each one is either a gated decision or off the table (round 1, "all five"):

• A. Spend money without Jason.
• B. Speak externally as Jason without his approval.
• C. Give agents Jason's personal credentials. Each role gets its own.
• D. Become a multi-tenant SaaS in v1. There is no hosted SaaS in v1.
• E. Replace Claude Code, Codex or Pi. It wraps them.

Where it runs

Mosaic Stack stays self-hosted open source. The licence is open, and Jason decides it later.

Self-hosted, on Jason's machines and homelab (round 1, "A first"). Cloud workers aren't ruled out later.

Out of scope for v1

Round 2, "all":

• businesses other than Mosaic Stack (SetSpark joins after v1);
• minting credentials (v1 hands out tokens Jason creates);
• Codex (v1 covers Pi and Claude Code, and Codex comes next);
• Pocket ID and SSO;
• access from beyond localhost.

Requirements

Every task the stack creates cites one of these ids. A task with no parent requirement is refused.

Roles

• REQ-ROLE-1. Each role is a reviewed file, roles/<name>.json at version 2. The file holds:

  • a contract;
  • an authority map over a closed vocabulary of actions;
  • the credentials it needs, by service and scope.

  Any action the file doesn't list is gated.

• REQ-ROLE-2. Each role instance has one holder at a time. The assistant is the exception: it has one holder per thread at a time. A claim takes a lock and logs it, and releasing the role or ending the run frees it. The chief of staff may end another role's run, and that act is logged with its reason. Anyone else who revokes a stuck holder needs a resolved decision, and the revoke cites it.

• REQ-ROLE-3. An organization file declares the role instances, the arbiters and the credential references. The user and the chief of staff write it. The chief of staff's writes go through a broker verb that logs each change. No other role writes it. A missing or invalid file fails closed. (Q133, confirmed as Q140: "We need the human and the Chief of Staff to be able to edit the Business file(s)".)

• REQ-ROLE-4. The first organization is Mosaic Stack, with six role instances:

  • chief of staff;
  • assistant;
  • PM, held by Sage;
  • CTO, held by Darkwing;
  • coder;
  • reviewer.

  The schema can also declare CEO, CFO and the other C-suite roles. The assistant's name is set in the organization file. Jason's may be named Mos.

Added in version 1.2:

• REQ-COS-1. The chief of staff runs the organization. It hires and terminates role instances, owns the organization's structure and is the only role that launches sessions (REQ-LAUNCH-1). It takes work from the assistant and assigns it through the roles that do it. It never talks to the user. Gated decisions still reach the human through the inbox (REQ-DEC-2, REQ-DEC-4).
• REQ-ASSIST-1. The assistant is the user's main agent. Each user has one assistant role per organization. It talks with the user, and it passes work for the organization to the chief of staff. It doesn't direct other agents, create or assign tasks, or launch sessions.
• REQ-ASSIST-2. The broker limits the assistant's messages, not its contract alone:
  • the assistant may send only to the user, in the thread, and to the chief of staff;
  • only the user and the chief of staff may send to the assistant;
  • every refused send is logged with its reason.

Variables

• REQ-VAR-1. Variables come in four layers: system, business, project and agent. Every key is declared in code with a type, the layers allowed to set it, and a merge rule.
  • The most specific layer wins for plain values.
  • Limits intersect, so a lower layer can only narrow them.
  • An unknown key is refused, and so is a key set at a layer it isn't allowed in.
• REQ-VAR-2. ~/.config/mosaic-dev/config.json stays the only system config, and nothing writes it automatically. A secret appears only as a reference, either a file path or an environment variable name. Only the broker reads a secret's contents. It holds them in memory and never logs or writes them. Everything else checks a referenced file with stat.

Credentials

• REQ-CRED-1. Every role instance has its own token for each service (Gitea, Vikunja). The broker holds them, and they never enter an agent's environment or files. In v1 Jason creates them by hand from a runbook Sage writes (round 3, 1A):
  • in Gitea, a new bot user per role, named <business>-<role>-bot, for example mosaic-stack-pm-bot (round 3, 2A; lead decision 58);
  • in Vikunja, a bot-<business>-<role> user per role, plus one read-only bot-<business>-sync that does all polling (lead decisions 52 and 58).
• REQ-CRED-2. A session that finds only founder credentials stops.

Decisions

• REQ-DEC-1. Every decision is a record in an append-only SQLite table. The record holds:

  • the role and run that raised it;
  • its class and action;
  • the options and a recommendation;
  • who resolved it;
  • its timestamps.

  A correction is a new row.

• REQ-DEC-2. Routing follows the decision's class:

  • routine and within-role decisions are logged;
  • cross-role decisions go to the business's arbiter for that domain;
  • gated decisions go to the human.

• REQ-DEC-3. A human resolution, by an authorized human, comes only from a mosaic CLI session started outside any agent run. Agents reach the decision store only through a broker. The broker stamps role and run from the launch record.

• REQ-DEC-4. A gated decision that blocks work reaches an authorized human right away: in the CLI inbox, plus a Discord DM sent through the existing connector (#1509). Everything else goes into one daily digest at 08:00 Central. (Round 2, answers 2A and 3A; round 3, 4A and 5A.)

Messages

• REQ-MSG-1. Messages are addressed to a role. They are append-only and go to whoever currently holds the role. A message to or from the assistant also names its thread and goes to that thread's holder. When the assistant sends work to the chief of staff, the reply comes back to the same thread. T3 and Discord carry messages; the address is still the role.

Tasks

• REQ-TASK-1. Tasks live in Vikunja, reached through /api/v2 with a bot token for each role. Each task cites a requirement id. Each task field has one writing role, listed in the slice 1 brief's field table, and the assigned role writes the task's state. Vikunja's token scopes cover whole route groups, so the broker's verbs enforce this, not the tokens. A person's edits come in as events.
• REQ-TASK-2. Polling is the source of truth. Every 30 seconds the sync bot reads each project's open-task board and the tasks updated since the last check, so column moves and deletions of open tasks show up within one poll. An hourly full reconcile catches the rest. Slice 1 uses no webhooks. (Lead decisions 51 and 52.)
• REQ-TASK-3. The installer offers two choices: point at an existing Vikunja, or deploy the bundled one. The bundled one is the unmodified upstream image. No Vikunja code enters the repository.
• REQ-TASK-4. The queue keeps the agents' lock, review rounds and audit log. No field syncs in both directions.

Interface

• REQ-CLI-1. mosaic is the front door. From it Jason can:
  • talk to the assistant in a project thread they choose or create;
  • see the decision inbox and resolve decisions;
  • see tasks and agents;
  • follow the trail of any piece of work.
• REQ-CLI-2. The assistant session that mosaic talks to is one the stack launches and owns, running Pi or Claude Code without a window. The product doesn't depend on T3. (Round 2, answer 5A.)
• REQ-WEB-1. The WebUI shows the same data as the CLI: conversations, the inbox, tasks, agents and trails. It has a chat area that lists the user's projects and the named threads in each, with one conversation view per thread where the user talks to the assistant. The user creates and names projects and threads there without a terminal. Its Settings view shows every agent limit, the usage counted against each, and the model each role instance runs, and lets the user change them (REQ-LIMIT-1 to REQ-LIMIT-3).

Launching

• REQ-LAUNCH-1. The chief of staff launches role sessions within the agent limits written in the organization file (REQ-LIMIT-1 to REQ-LIMIT-3):

  • role instances only;
  • a launch that would exceed any agent limit is refused, and the refusal is logged with the limit it hit;
  • every launch is logged with its harness, provider, model, and the account or key it runs on;
  • revocable with one word.

  Assistant thread sessions are the exception to who launches. The stack starts one when the user opens or writes to a thread, and ends it after the thread has been idle for the time the organization file sets. A running thread session counts against the limits like any other. An idle thread holds no session and counts against none. The stack starts the chief of staff itself. (Round 2, answer 6A; Q147; Q150.)

Added in version 1.2. Jason, Q150, verbatim: "No hard cap on agent limits. All tunable. Agent limit: A parallel execution limit arbitrarily set by the user or COS. This limit can apply to: overall executing agent limit across all models; provider parallel agent limit; provider parallel agent limit by model; daily quota limit based on OAuth account limit or CLIProxyAPI config in Mosaic Stack; absolute token limit per agent, model, provider, or API key".

• REQ-LIMIT-1. Agent limits are settings with no ceiling in code. The user and the chief of staff view and change them from the WebUI's Settings view and from a mosaic command, without editing a file. The chief of staff changes them through its organization-file broker verb (REQ-ROLE-3). The same places view and change the model each role instance runs. The running-session limits are:

  • the total number of sessions running at once, across all models;
  • the number running at once per provider;
  • the number running at once per provider and model. The default is 4 Opus and 4 Sonnet, as a default that can be changed, not a cap.

  Any kind may be left unset, which means no limit of that kind. A value is a whole number of 0 or more, and 0 stops new launches of that kind. A change is checked by the same rules as the organization file, then written to it and logged with who made it and the old and new values. An invalid value is refused, and the old value stays. A change applies to the next launch without a restart, and lowering a limit doesn't end sessions already running.

• REQ-LIMIT-2. A daily quota per OAuth account, or per client key of the CLIProxyAPI that Mosaic Stack configures. The stack counts the tokens its sessions use against the account or key each ran on, and the day resets at a time and time zone set with the quota. When an account or key reaches its quota, new launches on it are refused, and running sessions on it stop at the end of their current turn. Both are logged. The count covers sessions the stack ran. Use of the same account outside the stack isn't counted, and Settings says so. Measuring the quota in tokens is a draft position: Q150 names no unit, and OAuth plans meter by usage windows, not daily tokens.

• REQ-LIMIT-3. A token limit per role instance, model, provider or API key. Each limit counts the tokens its subject has used since the limit was set or last reset, and the user and the chief of staff can reset it. A count is the sum of every kind the harness reports (input, output, cache write and cache read), and Settings shows each kind. A launch whose subject is at its limit is refused, and a running session that reaches a limit is stopped at the end of its current turn. Both are logged with the limit and the count.

Meta-harness

• REQ-HARN-1. The meta-harness generates each session's launch bundle from the role and the resolved variables:

  • the prompt;
  • the policy;
  • skills;
  • typed tools for the vocabulary actions;
  • a manifest.

  Pi comes first, then Claude Code. Codex comes after v1.

• REQ-HARN-2. Four layers actually enforce the rules:

  • credential scope;
  • verbs that refuse without a resolved decision;
  • the harness's tool limit;
  • a container.

  Hooks only refuse early and log, and no document may call them enforcement. A probe run against the live harnesses must pass before any build relies on a block.

Events

• REQ-EVT-1. Every step in slice 1 emits an event to the append-only store. Measures are computed from events, never from tagging chat messages by hand.

Organizations

Added in version 1.1 (decision 03130d08).

• REQ-ORG-1. "Business" is renamed "organization". One install holds one or more organizations, and each organization has its own bus as the tenant boundary.
• REQ-ORG-2. The data model is install, then organization, then projects, then threads, so v1 doesn't lock in one human per organization.
• REQ-USER-1. Users and role-based access control exist at install and organization level. An agent belongs to one organization and reaches only its allowed projects and threads.
• REQ-USER-2. Only the user who owns a thread reads it or writes to it, plus that user's assistant and the chief of staff's replies on work the thread sent. This fills in REQ-USER-1's "threads" for the chat area. Added in version 1.2.
• REQ-THREAD-1. Threads live under projects.
• REQ-THREAD-2. The user creates projects and names threads inside them, from the CLI or the WebUI. Each thread is a separate assistant session. A thread's messages are kept. When the user comes back to a thread, after an idle stop or a restart, the assistant picks up where it left off with that history. One thread's conversation never appears in another's. Added in version 1.2.
• REQ-TPL-1. Templates exist for agent roles and for organization types.
• REQ-FED-1. Installs can federate with each other. This is post-v1.

Acceptance criteria and success measures

v1 is done when Jason gives one-sentence requests to the assistant, in a thread, from the CLI or the WebUI, and Mosaic Stack builds pieces of itself from them, five pieces in a row. For each piece:

• only gated decisions reach Jason;
• every step leaves a trail in the CLI and the WebUI.

(Round 1, answer A; the assistant and threads from version 1.2.)

Technical considerations

• Vikunja v2.7.0 is AGPL-3.0. Its API tokens can't create users or mint more tokens. A Mosaic-owned account mints one bot user and one scoped, expiring token per role. The owner password for that account is the one high-value Vikunja secret. Instance admin features need a paid licence, and the plan doesn't use them. Source: agents/researcher/work/2026-10-04_vikunja-pocketid.md.
• Gitea tokens never expire, and creating one needs a password or the host shell. Rotation will be a scheduled step with a record.
• Pocket ID v2.17.0 is BSD-2. It offers passkey-only login for people and a client-credentials flow, but it can't issue tokens that Vikunja or Gitea accept. Agents use per-service role tokens. Pocket ID is wired in after v1.
• Decisions, messages, role claims and events share one SQLite file, <dataRoot>/bus/bus.sqlite. A guard on every table refuses UPDATE, DELETE and REPLACE. Run records stay write-once files.
• None of the three harnesses' hooks fails closed by default except Pi's tool_call. Source: agents/filbert/work/meta-harness-survey-2026-10-04.md.
• Version 1.2:
  • The organization file's projects key names git repositories to clone (packages/seat/src/checkout.mjs:282-296). A REQ-ORG-2 project is the user's container for threads. The build has to keep the two apart, or define one in terms of the other, before the chat area stores projects.
  • Threads change the bus schema: messages, claims and deliveries gain a thread. The bus refuses a database whose schema doesn't match (store.mjs:113-115), so this needs a migration and a re-pin with downtime.
  • Claude Code resumes a conversation only inside one launch today, because its session directory and HOME are per run (launcher.mjs:204-206, sandbox.mjs:157). REQ-THREAD-2 needs a per-thread session store that outlives the run, or a rebuild of context from the thread's messages.
  • Limits today: launch.max is keyed by model family, and a launch's family is the one key its model name contains (packages/seat/src/session.mjs:52-57). Each count must be 0 to LAUNCH_CEILING = { opus: 4, sonnet: 4 } (packages/business/src/vocabulary.mjs:86, business.mjs:129-137). The launcher reads the file once at start (launcher.mjs:123), so a change needs a bus restart. REQ-LIMIT-1 removes the ceiling, replaces family matching with a model table that names each model's provider, and re-reads limits at each launch. Jason's file needs a one-time migration from { opus: 4, sonnet: 4 }.
  • The stack doesn't know a session's provider today. The only provider setting is the system-level execution.provider (vars.mjs:84-87), read by sessionModel (packages/harness/src/bundle.mjs:49-55). Claude Code sessions reach whatever ANTHROPIC_BASE_URL points at, or Anthropic when it's unset.
  • Tokens are on disk today, and nothing reads them:
    • Claude Code: the adapter uses --output-format text (adapters/claude/adapter.sh), so the runner sees only the answer. Claude Code's own transcript, in the run's HOME at home/.claude/projects/<dir>/<session id>.jsonl, has model and usage (input, output, cache write, cache read tokens) on each answer line. Checked on run re32fc7bd8143, model claude-sonnet-5-5.
    • Pi: the session file in the run's session directory has provider, model and usage (input, output, cacheRead, cacheWrite, totalTokens, cost) on each answer line. Checked on a Researcher session, provider zai.
    • The launch log has harness, model and family per launch, and no tokens (launcher.mjs:269, :294).
  • Today every Claude Code session runs on one credential, which the bus unit's environment file sets (SESSION_CREDENTIALS, packages/seat/src/session.mjs:76, decision 119). The stack has no name for that account. A quota per account needs the organization file to name each account and its credential reference (never the secret, invariant 3), and the launch to pick one and log its name. More than one account at a time needs the bus to hand a credential to each session, which is the open question in the #237 design row.
  • CLIProxyAPI, from Researcher's stand-in test (commit 587e64a27, agents/researcher/work/i1-proxy-test/REPORT.md): usage counters are kept per upstream credential, not per client key. Per-request events name the client key, but they last 60 seconds, a read removes them, and they carry the full plaintext key. All of it is behind the management API, which no agent calls. The stand-in didn't model token counts. So the stack can't read per-key usage from the proxy today. It counts its own sessions' tokens instead, and a per-key quota needs the stack to issue the keys (#237).
  • Token limits stop a session at the end of a turn, because the runner learns usage only when the turn ends. A long turn can go past its limit. Stopping inside a turn needs the runner to read streamed usage from each harness, which changes the adapter contract (stdout is the answer only, adapters/README.md).

Risks and open questions

• In slice 1, agents run as Jason's OS user (round 3, 3A). They can write anything that user can write. Until seats run in a container, which comes next, the broker is a rule they follow, not a wall. What does hold in slice 1 is that agents never hold service tokens.
• Vikunja doesn't enforce If-Match. The broker compares before it writes, and a person editing in the same moment can still be overwritten in an owned field (lead decision 51).
• The Vikunja owner password and Gitea token creation are gated. Jason holds them.
• With no ceiling in code, the chief of staff can raise its own launch capacity and spend (REQ-LIMIT-1, Q150). The controls are the change log, with who made each change and the old and new values, and the user's power to change it back.
• A quota or token limit counts only what the stack ran. It can't see the provider's own remaining quota or use of the same account elsewhere.

Milestones

Slice 1, in the order on the foundation direction page. The slice 1 brief maps each step to requirement ids. CHAT-03's Gate E demonstration happens during the slice 1 WebUI step, not separately (round 3, 7B).