Usage: add cost summaries to /usage + mac menu

docs/concepts/usage-tracking.md

@@ -13,6 +13,7 @@ read_when:
 ## Where it shows up
 - `/status` in chats: emoji‑rich status card with session tokens + estimated cost (API key only). Provider usage shows for the **current model provider** when available.
 - `/usage off|tokens|full` in chats: per-response usage footer (OAuth shows tokens only).
+- `/usage cost` in chats: local cost summary aggregated from Clawdbot session logs.
 - CLI: `clawdbot status --usage` prints a full per-provider breakdown.
 - CLI: `clawdbot channels list` prints the same usage snapshot alongside provider config (use `--no-usage` to skip).
 - macOS menu bar: “Usage” section under Context (only if available).

docs/token-use.md

@@ -45,6 +45,7 @@ Use these in chat:
 - `/usage off|tokens|full` → appends a **per-response usage footer** to every reply.
   - Persists per session (stored as `responseUsage`).
   - OAuth auth **hides cost** (tokens only).
+- `/usage cost` → shows a local cost summary from Clawdbot session logs.
 
 Other surfaces:
 

docs/tools/slash-commands.md

@@ -64,7 +64,7 @@ Text + native (when enabled):
 - `/subagents list|stop|log|info|send` (inspect, stop, log, or message sub-agent runs for the current session)
 - `/config show|get|set|unset` (persist config to disk, owner-only; requires `commands.config: true`)
 - `/debug show|set|unset|reset` (runtime overrides, owner-only; requires `commands.debug: true`)
-- `/usage off|tokens|full` (per-response usage footer)
+- `/usage off|tokens|full|cost` (per-response usage footer or local cost summary)
 - `/stop`
 - `/restart`
 - `/dock-telegram` (alias: `/dock_telegram`) (switch replies to Telegram)
@@ -91,7 +91,7 @@ Text-only:
 Notes:
 - Commands accept an optional `:` between the command and args (e.g. `/think: high`, `/send: on`, `/help:`).
 - For full provider usage breakdown, use `clawdbot status --usage`.
-- `/usage` controls the per-response usage footer. It only shows dollar cost when the model uses an API key (OAuth hides cost).
+- `/usage` controls the per-response usage footer; `/usage cost` prints a local cost summary from Clawdbot session logs.
 - `/restart` is disabled by default; set `commands.restart: true` to enable it.
 - `/verbose` is meant for debugging and extra visibility; keep it **off** in normal use.
 - `/reasoning` (and `/verbose`) are risky in group settings: they may reveal internal reasoning or tool output you did not intend to expose. Prefer leaving them off, especially in group chats.