feat(amico-run): ship amico-slack as the package's Slack client bin (unified-fleet slice 2)

[aarontrowbridge]

Important

Problem

The only usable Slack poster (~/.local/bin/amico-slack, Python) is hand-planted on one machine with no versioned source — the product has no Slack client, and the unified-fleet spec's slice 2 ships one.

Approach

Port the CLI into @amicode/amico-run as a zero-dep Node bin (node:https, the existing launcher/bin pattern), absorbing the DM path as a dm command so the internal httpx client can retire. One client — the Python script becomes the executable reference, then yields authority the moment the bin lands.

Approaches Considered

• Ship the Python script inside the extension — rejected: Python runtime friction on user machines; the Node bin matches amico-run's launcher pattern.
• Keep both clients indefinitely — rejected: two clients is the disease being cured.
• (chosen) Node bin port with ported tests.

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Acceptance Criteria

1. The bin supports send (incl. --file, --thread, --as-user), read, whois, delete, status, and new dm <email|@handle>.
2. Voice contract intact: default posts as the app with no footer; --as-user appends _de Amico_; legacy Authored by Amico stripped idempotently (ported tests prove it).
3. Token layering: credential store → ~/.amico/slack/token (0600) → SLACK_BOT_TOKEN env; absent all → clean "no Slack configured" exit, never a crash.
4. ~/.local/bin/amico-slack becomes a symlink to the shipped bin; the SKILL.md cli_tool resolves from PATH.
5. The papers-digest verb and morning-brief workflow post through the bin; the internal httpx SlackClient retires to the email-lookup only, or fully if dm covers it.
6. With no Slack configured anywhere, the extension and verbs are inert and silent (product guarantee).

Key Decisions

• Port, not rewrite: the Python script is the executable reference; port its test cases (footer idempotence, mrkdwn flattening, mention resolution) alongside.
• dm absorbs users.lookupByEmail → conversations.open → chat.postMessage (needs users:read.email — added in slice 0).

Source

• Durable record: specs/spec-20260818-150711-unified-amico-fleet-slack.md (personal vault, rev 2) — slice 2.

[aarontrowbridge]

Target-package check (2026-08-20, Aaron flagged a concern): @amicode/amico-run is not being retired — the depth-1 redesign dissolves the orchestrator personas and explicitly names "the amico-run lineage" as the CLI spine (spec-20260708-112732 §7.3); the installation-architecture spec (2026-08-17) and the standalone-app RFC #302 both carry it as the VS Code-independent spine. Actual retirements in flight — the vendored opencode fork binary (#451) and the pulse-designer agent shell (#389) — don't touch this package. The port stands as scoped; if a newer decision says otherwise, re-home before starting and update this issue.