Episode 16: Q&A β Session, Context & Token Basics
This Episode: The 7 most common questions developers ask after first using Claude HUD.
Q1: What's the difference between a Session and a conversation?
No difference. One session = one Claude Code conversation = from launch to exit (or /clear). The Session ID is the UUID in the .jsonl filename.
/clear resets the session (clears conversation history, starts new dialogue), but the transcript file and Session ID remain. Exiting and relaunching Claude Code creates a truly new session.
Q2: What does 200K context window mean?
200K = 200,000 tokens. Tokens and characters aren't 1:1:
| Language | 1 Token β |
|---|---|
| English | 0.75 words |
| Chinese | 1-2 characters |
| Code | Irregular, const x = 1; β 5-7 tokens |
200K tokens β 150,000 English words, or 300-400K Chinese characters.
Q3: Why did context jump 40% after reading files?
The Read tool puts entire file contents into context as tool_result. 6 files (200-400 lines each) β 40K-60K tokens, consuming 20-30% of the 200K window.
Avoidance: Use Grep for relevant lines only, or Read file.ts:100:50 to read just 50 lines.
Q4: Which costs more β Input or Output tokens?
Output is 5Γ more expensive (Opus model):
| Token Type | Opus Price | Sonnet Price |
|---|---|---|
| Input | $3/MTok | $0.80/MTok |
| Output | $15/MTok | $4/MTok |
| Cache read | $0.30/MTok | $0.08/MTok |
Saving output matters more. Caveman mode, specific instructions, "only change code, don't explain" all save output.
Q5: Is in: 318 in HUD cumulative for the whole session?
No. The identity line's (in: 318, cache: 66k) is for the current single API request.
The Session Tokens line (tokens 1.3M) is session cumulative. They complement each other.
Q6: What's the difference between Session Tokens and Identity line?
| Identity Line | Session Tokens Line | |
|---|---|---|
| Scope | Single API request | Entire session cumulative |
| Data source | stdin current_usage |
transcript sessionTokens |
| Purpose | See how much this turn cost | See total session consumption |
Q7: What does 95% auto-compression lose?
All details from early conversations are lost, only summaries remain:
- Lost: File contents, tool return results, specific code snippets, exact error messages
- Kept: Semantic summary of conversations
Compression is irreversible. Proactively manage at 85% rather than waiting for 95%.
Next Episode: Episode 17 continues Q&A β advanced questions about Cache mechanisms and token optimization.