v0.4.0

Added

• Chat commands with autocomplete: new built-ins /help, /clear, /sessions, /resume <session> and /quit join /plan, /normal, /rewind, /context and /rename. In the fullscreen UI, typing / opens a popup that filters built-ins and skills as you type — ↑/↓ select, Tab completes, Enter runs, Esc dismisses. /resume switches sessions inside the running loop; /clear wipes the context and the screen.
• MCP over HTTP: entries in mcp.json with a type of http/sse or a bare url connect via Streamable-HTTP POST instead of spawning a subprocess — JSON and SSE answers alike, the session id the server assigns carried on every later request, bearer tokens from the environment via ${VAR} header expansion. Everything the stdio path already had applies unchanged: approval gate, untrusted marking, restart-once, per-call timeout (#84).
• smith stats: aggregates cost and tokens across all saved sessions from the index alone — a grand total, a prompt/completion/cache split and a per-provider/model breakdown. Unknown rates add tokens but show n/a, never a guess; [pricing] overrides from config apply (#85).
• Session hygiene: smith sessions delete <ref>… removes sessions by name or id — file, directory and index entry — and smith sessions prune drops sessions older than --older-than (30d default) while keeping --keep-last N; both support --dry-run. The newest session is never pruned, and [sessions] retention_days prunes at startup (#82).
• Cost per session: smith sessions shows a COST column per row, priced from the index and honouring [pricing] overrides; unknown models and entries predating usage tracking show n/a (#83).

Changed

• The fullscreen UI now sits on anvil: text, editor and popup layers, the event loop, terminal handling and the live region come from the published anvil and termisu libraries — smith keeps the domain: what keys mean while a popup is open, the status line, the event-stream-to-blocks renderer and the gates. src/smith/ui shrank from 2 699 to 1 392 lines.