Overview

Add a persistent status bar to the Hermes CLI that displays the current model, token usage, context window fullness, session duration, and estimated cost. This is the single highest-impact, lowest-effort CLI improvement available.

Every modern AI coding CLI (Aider, Claude Code, Toad) shows token/cost information. Hermes shows nothing — users have no visibility into how full their context window is, what model they're using, or how much a session costs until they hit a wall (context overflow, unexpected bill).

Split from #504 for atomicity. The companion feature (rich rendering + navigation) is tracked in #684.

Research Findings

What Competitors Show

Aider: Real-time token/cost display per interaction. Shows tokens used per file in context.

Claude Code: Token counter in the prompt bar. Context window percentage visible at all times. /usage command for detailed breakdown.

Toad CLI: Model indicator, streaming status, connection health in the status line.

The Pattern

A thin status bar (1-2 lines) that updates after each interaction. Always visible. Color-coded thresholds for context fullness.

Current State in Hermes Agent

No status bar exists. The current prompt_toolkit layout (cli.py ~line 3289) is:

HSplit([
    Window(height=0),        # spacer
    sudo_widget,             # conditional sudo password
    approval_widget,         # conditional approval
    clarify_widget,          # conditional clarify
    spacer,                  # flexible space
    input_rule_top,          # bronze ─ rule
    image_bar,               # clipboard image badges
    input_area,              # TextArea
    input_rule_bot,          # bronze ─ rule
    CompletionsMenu,         # autocomplete
])

Token data IS available — the OpenAI API response includes a usage field with prompt_tokens, completion_tokens, and total_tokens. This data just isn't surfaced to the user.

Model info IS available — stored in session state, displayed in the banner at startup, but not persistently visible.

Implementation Plan

Skill vs. Tool Classification

This is a core codebase change to cli.py. It requires modifications to the prompt_toolkit layout and a data pipeline from API responses to the status bar display.

Specification

Status bar layout (1 line, above the input area):

 ⚕ claude-sonnet-4-20250514 │ Tokens: 12,450 / 200K │ [██████░░░░] 62% │ Cost: $0.23 │ 14m

Components:

• Model name: current model (truncated if needed)
• Token count: prompt + completion tokens / max context
• Context bar: visual [██████░░░░] with color coding:
  • Green: < 50%
  • Yellow: 50-80%
  • Red: > 80%
  • Blinking red: > 95% (imminent overflow)
• Cost estimate: cumulative session cost based on per-token pricing
• Duration: session elapsed time

Data pipeline:

1. After each API call, extract usage from response
2. Update a shared state dict (_status_state)
3. Trigger app.invalidate() to repaint the status bar
4. Cost calculation: prompt_tokens * input_price + completion_tokens * output_price

Model pricing (configurable in config.yaml):

pricing:
  claude-sonnet-4-20250514:
    input: 3.0    # per million tokens
    output: 15.0
  gpt-4o:
    input: 2.5
    output: 10.0
  # fallback for unknown models
  default:
    input: 1.0
    output: 3.0

/usage command: Detailed breakdown:

Session Usage Report
━━━━━━━━━━━━━━━━━━━
Model:       claude-sonnet-4-20250514
Duration:    14m 32s
Turns:       7

Tokens:
  Prompt:     10,230 (input)
  Completion:  2,220 (output)
  Total:      12,450
  Context:    62% of 200,000

Cost:
  Input:      $0.031
  Output:     $0.033
  Total:      $0.064

Deliverables

• Status bar Window in prompt_toolkit layout (above input_rule_top)
• FormattedTextControl with dynamic content from _status_state
• Token extraction from API response usage field
• Context window max lookup per model (from model_metadata.py)
• Color-coded context fullness bar
• Cost estimation with configurable per-model pricing
• Session timer (start time → elapsed)
• /usage command with detailed breakdown
• Compact mode handling (abbreviate or hide status bar in narrow terminals)
• Tests for token tracking, cost calculation, display formatting

Pros & Cons

Pros

• Highest impact-to-effort ratio of any CLI improvement
• Prevents surprise context overflow (users see it coming)
• Cost visibility saves money (users learn which prompts are expensive)
• Small, self-contained change (one new Window in the HSplit)
• No refactoring required — purely additive
• Can ship in 1-2 days

Cons / Risks

• Token counts from server are delayed (reported after completion, not during streaming)
• Cost estimation requires maintaining a pricing table (could go stale)
• Status bar takes 1 line of vertical space (mitigated by compact mode)
• Some terminals may render the color bar poorly (test mosh, tmux, SSH)

Open Questions

• Should the status bar be above the input (like vim's statusline) or between output and input?
• Should cost tracking be opt-in (some users might find it anxiety-inducing)?
• Should we use tiktoken for real-time token estimation DURING streaming, or only report after completion?
• Should token counts include tool call tokens (they can be substantial)?

References

• Aider cost tracking — per-interaction token/cost display
• Claude Code context management — token counter in prompt
• Existing code: cli.py layout (~line 3289) — insertion point for status bar
• Existing code: model_metadata.py — context window sizes per model
• Existing code: FormattedTextControl pattern used by clarify_widget — reusable for status bar
• Split from closed Feature: Enhanced CLI TUI — Rich Markdown Rendering, Diff Previews, Token Tracking & Navigable Output #504
• Related: Feature: LLM-Based Context Condensation for Long Sessions #480 (Context Condensation — status bar shows when condensation is imminent)
• Related: [Bug]: Blinking cursor or switching emojis causing prompt lines to flash repeatedly in terminal #464 (blinking cursor — status bar changes should avoid exacerbating this)
• Subsumes: [UX]: Async slash commands (/skills search, etc.) need a loading indicator #636 (async loading indicator — status bar can show "processing..." state)