# T3 report: `mosaic fleet agent new`

## Changed

- Added `packages/mosaic/src/fleet/fleet-agent-scaffold.ts`.
  - Creates user-owned seats at `~/.mosaic/fleet/agents/<name>` (test seam: `fleetDataHome`, environment default: `MOSAIC_DATA_HOME`).
  - Writes schema-one `profile.json` with default `harness: "claude"`, `bundle: "primary"`, optional `model`, `overlay: "overlay.json"`, and mandatory `env.MOSAIC_AGENT_NAME`.
  - Writes a positive `SOUL.md` identity and materializes that identity in `.claude/CLAUDE.md` or `.pi/AGENTS.md`.
  - Writes `overlay.json` as `{}`. Claude homes get `.claude.json` with `hasCompletedOnboarding: true` and `theme: "dark"`. No settings file is composed.
  - Creates the appropriate credential symlink (`.credentials.json` for Claude, `auth.json` for Pi), allowing an intentional dangling destination and reporting it at the command surface.
  - Compares every existing object (including link targets as link text), succeeds only byte-identically, and otherwise refuses with the differing paths.
- Added `packages/mosaic/src/commands/fleet-agent-scaffold-command.ts` and wired `fleet agent new <name> [--harness claude|pi] [--bundle B] [--model M]` in `packages/mosaic/src/commands/fleet.ts`.
- Added `packages/mosaic/src/commands/fleet-agent-scaffold-command.spec.ts` with temp-root-only coverage: exact Claude/Pi layouts, literal quote/backtick/`$( )` handling, unsafe names and option failures, idempotence, changed-file refusal, and credential-link comparison.

## Reconciliation

`fleet-agent-crud-command.ts` currently registers roster-v2 `get/create/update/delete/plan` directly under `mosaic fleet`; it has no `agent new` command or profile schema. T3 adds an `agent` namespace for the profile-owned user-data scaffold and leaves roster-v2 CRUD unchanged.

No roster projection is created. Current roster-v2 requires fields that cannot be derived from the new profile (`class`, provider, working directory, reasoning, tool policy, lifecycle), while no current `mosaic fleet launch <name>` consumes these profiles. Writing such a roster entry would create the forbidden second registry and invent semantics. The profile is therefore the sole state created here. When the launcher owns profile-to-roster projection, it must derive it there and emit the required actionable unscaffolded-name message.

## Validation

```text
$ pnpm install --frozen-lockfile
Done in 4.1s using pnpm v10.6.2

$ pnpm --filter @mosaicstack/mosaic exec vitest run src/commands/fleet-agent-scaffold-command.spec.ts
✓ src/commands/fleet-agent-scaffold-command.spec.ts (13 tests) 28ms
Test Files  1 passed (1)
Tests       13 passed (13)

$ pnpm --filter @mosaicstack/mosaic exec eslint src/fleet/fleet-agent-scaffold.ts src/commands/fleet-agent-scaffold-command.ts src/commands/fleet-agent-scaffold-command.spec.ts src/commands/fleet.ts
(exit 0)

$ pnpm exec prettier --check packages/mosaic/src/fleet/fleet-agent-scaffold.ts packages/mosaic/src/commands/fleet-agent-scaffold-command.ts packages/mosaic/src/commands/fleet-agent-scaffold-command.spec.ts packages/mosaic/src/commands/fleet.ts
All matched files use Prettier code style!

$ git diff --check
(exit 0)
```

`pnpm --filter @mosaicstack/mosaic typecheck` remains blocked by pre-existing unresolved workspace package entries (`@mosaicstack/brain`, `@mosaicstack/db`, `@mosaicstack/types`, and others). The typecheck output had no diagnostics naming T3 files. Running the pre-existing CRUD command spec is blocked by the same `@mosaicstack/db` Vite resolution failure through `fleet-backlog.ts`.

## Skipped ambiguity

The design asks for a generated harness-home `settings.json` as part of an earlier generic home-template description, but the task explicitly says composed settings are left to launch. T3 creates no `settings.json`; launch composition remains the owner.
