feat: --resume on new, manifest-driven restore, send --wait-for-prompt, sessions --json

[motin]

Summary

Closes four ergonomic gaps surfaced while migrating an 18-session Claude Code fleet from Wave to Tabby.

1. cctabs new <name> <dir> --resume <session-id> — pass-through to claude --resume <id> --name <name> plus the configured claude.flags from ~/.config/cctabs/config.toml. Validates the session ID against ~/.claude/projects/<slug>/ and warns (but proceeds) if missing. Combines with --worktree. Mutually exclusive with --prompt / --file.
2. cctabs restore --manifest <file|-> [--create-missing] — drives restore from an explicit {name, dir, session_id?}[] list (plain array, {sessions: […]}, or full {workspaces: [{sessions: […]}]} — accepts cctabs sessions --json output directly). Attaches to existing tabs in the current workspace; with --create-missing also spawns new ones.
3. cctabs send --wait-for-prompt [--wait-timeout <s>] — polls the buffer until a shell prompt ($ / % / > / ❯) is visible before sending. Closes a race observed when sending immediately after a Tabby POST /api/tabs/new. Off by default to preserve the existing fast path.
4. cctabs sessions --json — emits machine-readable JSON (per-workspace, per-session). Includes the resolved Claude session ID when inferable from ~/.claude/projects/<slug>/. Output pipes directly into cctabs restore --manifest -, closing the Wave→Tabby migration loop.

Plus a small infra fix: pass renderHeader: null to gunshi so --json (and any other piped) output isn't prefixed with the package banner.

Design decisions

• Manifest schema: accepts three shapes (array, {sessions}, or full {workspaces: [{sessions}]}) so callers can roundtrip sessions --json output with no transformation. name + dir (or cwd) are required; session_id is optional — when omitted, restore falls back to a name lookup in ~/.claude/projects/<slug-of-dir>/.
• --create-missing scope: limited to the current workspace. With Tabby that's the only workspace, and on Wave you almost always want to spawn into the window you're sitting in.
• --wait-for-prompt opt-in: existing callers don't need the latency; only freshly spawned tabs do. A --no-wait opt-out would be a wider change.
• --resume validation: warn-and-proceed rather than abort. The user may know better than we do (worktree corner cases, stale slug, etc.), so we don't block.

Test plan

• npm run typecheck clean
• npm run build clean
• cctabs sessions --json | jq '.workspaces[0].sessions | length' returns a number
• cctabs sessions --json | cctabs restore --manifest - --dry round-trips
• cctabs sessions --json | cctabs restore --manifest - --create-missing --dry shows spawn intent for the current tab
• cctabs new --resume <bad-id> warns and proceeds
• cctabs new --resume <id> --prompt foo errors cleanly
• End-to-end on Wave Terminal (only smoke-tested on Tabby)
• cctabs send --wait-for-prompt round-trip against a slow-to-prompt tab

🤖 Generated with Claude Code