Onboarding: point users at the existing `agentwire dev` helper session + make it carry the contributor role by default

[dotdevdotdev]

Premise correction (read first)

The original issue asked to make agentwire dev "a first-class, discoverable CLI command." That command already exists and is already discoverable in agentwire --help. This issue is therefore not about creating a command — it's about closing the onboarding gap (users don't know to run it) and changing the default role it carries.

Verified current state

• agentwire dev is a real subcommand. Registrar: agentwire/system_cli.py:558-573; implementation: cmd_dev at agentwire/system_cli.py:42-89.
• It already appears in agentwire --help as: dev Start/attach to dev agentwire session.
• What it does today (cmd_dev): start-or-attach a tmux session named agentwire, working dir = get_source_dir() (default ~/projects/agentwire-dev, agentwire/core.py:515-522), session type {agent}-bypass (full permissions), roles = agentwire + soul (system_cli.py:57), not the contributor role.
• The contributor role does not exist yet — it's defined by Add a bundled contributor role (onboarding + issue-filing + fork/PR coaching) and make it the helper-session default; owner overrides locally #620 (still open). agentwire/roles/ currently has agentwire.md, no contributor.md.
• The first-run flow does not mention the helper session. agentwire init → onboarding "Next steps" (agentwire/onboarding.py:468-475) only points at agentwire portal start, the portal URL, and agentwire init --assisted (which spawns a throwaway agentwire-init/init-role session, onboarding.py:490-498). README Quick Start and docs/wiki/quickstart.md never mention agentwire dev either.
• The command-palette "open or start a project session" idea the original issue floated as a nice-to-have already ships for the user's own projects: New idea / New session / Open session actions exist (agentwire/static/js/command-palette.js:38-41). It does not surface the agentwire helper session, which is a separate thing.

Goal

Make the agentwire dev helper session a visible front door for new users, and make it carry the contributor role (#620) by default so a non-owner who runs it gets a persona that can install/configure, orchestrate their own projects, explain the system, and help them file issues or fork.

Two pieces of real work:

1. Default role: switch the role cmd_dev injects from agentwire to contributor (per Add a bundled contributor role (onboarding + issue-filing + fork/PR coaching) and make it the helper-session default; owner overrides locally #620). Blocked on Add a bundled contributor role (onboarding + issue-filing + fork/PR coaching) and make it the helper-session default; owner overrides locally #620 landing the role.
2. Onboarding discoverability: tell users the helper session exists, at the moments they'd look — first-run output, README/quickstart, and (optionally) a portal "Start here" affordance.

Scope

In scope:

• Change the default role in cmd_dev (agentwire/system_cli.py:57) to the contributor role once Add a bundled contributor role (onboarding + issue-filing + fork/PR coaching) and make it the helper-session default; owner overrides locally #620 ships (decide whether the owner-only agentwire role is still injected locally, or whether the owner-override role from Add a bundled contributor role (onboarding + issue-filing + fork/PR coaching) and make it the helper-session default; owner overrides locally #620 covers that).
• First-run nudge: add a line to the onboarding "Next steps" block (agentwire/onboarding.py:468-475) pointing the user at agentwire dev (and explaining, in one sentence, that it's a session that walks them through setup, wires up their projects, and explains the system).
• README/quickstart: add agentwire dev to the Quick Start sequence with a one-line description of what it's for.

Out of scope / nice-to-have:

• A dedicated portal "Start here / start the agentwire helper" command-palette entry or affordance. The palette already has project-session actions (command-palette.js:38-41); a helper-session entry could ride along but isn't required.
• Renaming dev to something more user-facing (e.g. it reads as developer-only). The original issue said "or equivalently named" — flag this as an open question, but renaming a shipped subcommand is a bigger, separate decision; default to keeping dev and improving the surrounding copy.

Approach

1. (after Add a bundled contributor role (onboarding + issue-filing + fork/PR coaching) and make it the helper-session default; owner overrides locally #620 merges) In cmd_dev (agentwire/system_cli.py:42-89), replace the hard-coded ["agentwire"] role list (line 57) with the contributor role. Keep inject_soul(...) wrapping. Confirm load_roles resolves contributor from agentwire/roles/contributor.md.
2. First-run copy in agentwire/onboarding.py (the skip_session "Next steps" branch, lines 468-475): add a step like agentwire dev with a short gloss. This is the highest-leverage onboarding surface — it's what every agentwire init run prints.
3. README + docs/wiki/quickstart.md: add agentwire dev to the documented getting-started path with a one-sentence "what it's for."
4. (optional) Portal affordance — only if cheap; the palette infra already exists.

Dependencies

• Add a bundled contributor role (onboarding + issue-filing + fork/PR coaching) and make it the helper-session default; owner overrides locally #620 (contributor role) — piece (1) is blocked on it. Pieces (2)/(3) (onboarding copy) can land independently and reference the existing agentwire dev immediately.

Verification

• agentwire init (default, non-assisted): the printed "Next steps" now names the helper session, so a fresh user lands on a clear instruction to run it.
• README/quickstart visibly include agentwire dev in the getting-started flow.
• After Add a bundled contributor role (onboarding + issue-filing + fork/PR coaching) and make it the helper-session default; owner overrides locally #620: agentwire dev on a clean machine spawns the agentwire session running the contributor role (verify via the session's role injection / agentwire roles for that session), and that session can install/configure, orchestrate the user's projects, explain the system, and help file an issue / fork (per Add a bundled contributor role (onboarding + issue-filing + fork/PR coaching) and make it the helper-session default; owner overrides locally #620).

[dotdevdotdev]

Implemented in #623 (draft), riding on #620.

• Onboarding 'Next steps' (onboarding.py) now names agentwire dev with a one-line gloss.
• cmd_dev switched to the contributor role (per Add a bundled contributor role (onboarding + issue-filing + fork/PR coaching) and make it the helper-session default; owner overrides locally #620).
• README Quick Start and docs/wiki/quickstart.md document agentwire dev.

Verify: full uv run pytest green.