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jason.woltjeandClaude Opus 5.5 fe5c68fa03 feat(harness): meta-harness and PM launching off T3 (#1523 , row 41)

Slice 1 S6. packages/harness runs a role session under the pi or claude
adapter behind a tool gate, and packages/seat holds the session and its
process. The bus host gains a launch socket: `mosaic bus start
<business> --pm <harness>:<model>` runs the PM without a window, the PM
launches role sessions through the broker within the business file's
`launch.max`, and every launch, refusal and end is a launch-log line and
a broker event. `mosaic talk`, `mosaic launches off|on|list` and
`mosaic stop <run>` are new CLI verbs. packages/bus gains the IPC ops
identity, authorize, refuse, endLaunch and credentialStatus, plus
Broker.endLaunch (decision 77); no socket verb, event kind or schema
changed. The session environment is an allowlist, and the runner exits
before claiming if a founder credential reaches it.

Filbert built it (agents/filbert/work/s6). Darkwing reviewed on #1523:
round 1 changes (26991/26995), round 2 changes (27004/27010), round 3
changes (27012/27032), round 4 approve (27033/27034) on manifest
08a78972, 42 paths.

Sage's gate on 64b0f9f1 (12:32Z), sequential and teed: node suites
business 60, bus 74, cli 83, control-board 124, conversation 182,
discord 178, harness 56, ledger 78, mosaic 69, queue 149, runs 41,
seat 27, tasks 51, webui 39, every one 0 failed; test-auth 15,
test-conductor 17, test-config 24, test-discord 66,
test-extension-package 18, test-foundation 44, test-queue 27,
test-release 14, test-task 98 and 26 without Docker, all 0 failed.
64b0f9f1..ee7f909b touches none of the 42 paths. It landed after the
Q14 hold ended at 2026-10-11T17:19:23.857Z. The recorded PM-to-coder
run on a scratch data root is still owed before row 41 moves to done.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

2026-10-11 12:22:50 -05:00

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Mosaic runtime adapters

An adapter is the entire harness-specific surface of the system. Everything upstream of an adapter — configuration, contracts, missions, tasks, run records — is harness-agnostic; everything inside an adapter may assume one specific agent runtime.

Contract

An adapter lives at:

/opt/mosaic/adapters/<name>/adapter.sh

and must be executable. The dispatcher (/opt/mosaic/src/run-agent.sh) selects it via MOSAIC_ADAPTER (default: pi) and execs it after the system prompt has been generated.

Inputs (environment):

Variable	Meaning
`MOSAIC_SYSTEM_PROMPT_FILE`	Absolute path to the generated system prompt (contracts + optional mission section). Read it; do not modify it.
`MOSAIC_REQUEST`	The exact user request text (may contain newlines).
`MOSAIC_PROVIDER`	Configured provider name.
`MOSAIC_MODEL`	Configured model id.

Optional, adapter-specific (documented per adapter):

Variable	Meaning
`MOSAIC_MOCK_RESPONSE`	mock only: the verbatim response to emit

Outputs:

stdout: the model response text — the only channel the orchestrator captures
stderr: diagnostics (never credentials)
exit 0: success; nonzero: failure

Rules

Adapters print ONLY the response on stdout. Status lines go to stderr.
Adapters never read configuration files; the resolved settings arrive via environment.
Adapters never write outside /var/lib/mosaic.
Adding a worker adapter requires: a new directory, the contract implementation, and adding the name to the allowlist in scripts/mosaic-config.mjs. A managed-session adapter (below) is selected by the launch bundle, not by execution.adapter, and is not on that allowlist unless it also works as a worker adapter.

Included adapters

pi — the pinned @earendil-works/pi-coding-agent CLI in noninteractive print mode (-p), ambient discovery disabled, stdin detached.
mock — deterministic echo of MOSAIC_MOCK_RESPONSE. Test-only: never use it where a real model response is required.
claude — the host's claude CLI, for managed sessions only (below). Not a worker adapter: the image has no claude, and the adapter refuses without the bundle's hook and MCP files.

Managed sessions (slice 1 S6)

The session runner (packages/harness/src/runner.mjs) runs one adapter call per turn on the host, as /bin/sh <adapters/<name>/adapter.sh> (the repository keeps adapters 0644; only the image sets the mode), in the session's workspace and its own process group. Same contract, plus:

Variable	Meaning
`MOSAIC_WORKSPACE`	The session's workspace; the adapter runs there.
`MOSAIC_SESSION_DIR`	The session's persistent directory; later turns resume the session kept there.
`MOSAIC_TOOLS`	The built-in tool limit (pi names for `pi`, Claude Code names for `claude`), comma-separated.
`MOSAIC_POLICY_FILE`, `MOSAIC_TOOLS_FILE`	The bundle's gate policy and typed tools.
`MOSAIC_TOOL_SOCKET`	The runner's tool socket, which the typed tools call.
`MOSAIC_TURN_MARKER`	`pi`: the extension writes it at `agent_end`; a pi turn that exits 0 without it failed.
`MOSAIC_EXTENSIONS`	`pi` only: extension files loaded with `-e`; a missing one exits 2.
`MOSAIC_CLAUDE_SETTINGS`, `MOSAIC_CLAUDE_MCP_CONFIG`	`claude` only: the bundle's gate hook and MCP server; required.

The layers each adapter relies on, and what they don't cover, are in packages/harness/README.md.

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