Add token-budget-advisor skill

Skill that intercepts prompts, estimates token consumption across 4
depth levels, and lets the user choose before Claude responds.

skills/token-budget-advisor/SKILL.md

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+---
+name: token-budget-advisor
+description: >-
+  Intercepts the response flow to offer the user an informed choice about
+  how much depth/tokens to consume — BEFORE responding. Use this skill
+  when the user wants to control token consumption, adjust response depth,
+  choose between short/long answers, or optimize their prompt.
+  TRIGGER when: "tokens", "token budget", "profundidad", "consumo",
+  "respuesta corta vs larga", "cuántos tokens", "ahorrar tokens",
+  "responde al 50%", "dame la versión corta", "quiero controlar cuánto usas",
+  "ajusta tu respuesta", "short version", "tldr", "brief", "in 25%",
+  "in 50%", "in 75%", "exhaustive", or any variant where the user wants
+  to control length, depth, or token usage — even without mentioning tokens.
+  DO NOT TRIGGER when: user has already specified a level in the current
+  session (maintain it) or the request is clearly a one-word answer.
+origin: community
+---
+
+# Token Budget Advisor (TBA)
+
+Intercept the response flow to offer the user a choice about response depth **before** Claude answers.
+
+## When to Use
+
+- User wants to control how long or detailed a response is
+- User mentions tokens, budget, depth, or response length
+- User says "short version", "tldr", "brief", "al 25%", "exhaustive", etc.
+- Any time the user wants to choose depth/detail level upfront
+
+**Do not trigger** when: user already set a level this session (maintain it silently), or the answer is trivially one line.
+
+## Workflow
+
+### Step 1 — Estimate input tokens
+
+Use the calibration tables below to estimate the prompt's token count mentally.
+
+**Chars-per-token by content type:**
+
+| Content type      | Chars / Token |
+|-------------------|---------------|
+| English natural   | ~4.0          |
+| Spanish natural   | ~3.5          |
+| Code              | ~3.0          |
+| JSON              | ~2.8          |
+| Markdown          | ~3.3          |
+
+Formula: `input_tokens ≈ char_count / chars_per_token`
+
+For mixed content, use the dominant type's ratio.
+
+### Step 2 — Estimate response size by complexity
+
+Classify the prompt, then apply the multiplier range to get the full response window:
+
+| Complexity   | Multiplier range | Example prompts                                      |
+|--------------|------------------|------------------------------------------------------|
+| Simple       | 3× – 8×          | "What is X?", yes/no, single fact                   |
+| Medium       | 8× – 20×         | "How does X work?"                                  |
+| Medium-High  | 10× – 25×        | Code request with context                           |
+| Complex      | 15× – 40×        | Multi-part analysis, comparisons, architecture      |
+| Creative     | 10× – 30×        | Stories, essays, narrative writing                  |
+
+Response window = `input_tokens × mult_min` to `input_tokens × mult_max` (cap at 8 000).
+
+### Step 3 — Present depth options
+
+Present this block **before** answering, using the actual estimated numbers:
+
+```
+Analyzing your prompt...
+
+Input: ~[N] tokens  |  Type: [type]  |  Complexity: [level]  |  Language: [lang]
+
+Choose your depth level:
+
+[1] Essential   (25%)  ->  ~[tokens]   Direct answer only, no preamble
+[2] Moderate    (50%)  ->  ~[tokens]   Answer + context + 1 example
+[3] Detailed    (75%)  ->  ~[tokens]   Full answer with alternatives
+[4] Exhaustive (100%)  ->  ~[tokens]   Everything, no limits
+
+Which level? (1-4 or say "25%", "50%", "75%", "100%")
+
+Precision: heuristic estimate ~85-90% accuracy (±15%).
+```
+
+Level token estimates (within the response window):
+- 25%  → `min + (max - min) × 0.15`
+- 50%  → `min + (max - min) × 0.45`
+- 75%  → `min + (max - min) × 0.75`
+- 100% → `max`
+
+### Step 4 — Respond at the chosen level
+
+| Level            | Target length       | Include                                             | Omit                                              |
+|------------------|---------------------|-----------------------------------------------------|---------------------------------------------------|
+| 25% Essential    | 2-4 sentences max   | Direct answer, key conclusion                       | Context, examples, nuance, alternatives           |
+| 50% Moderate     | 1-3 paragraphs      | Answer + necessary context + 1 example              | Deep analysis, edge cases, references             |
+| 75% Detailed     | Structured response | Multiple examples, pros/cons, alternatives          | Extreme edge cases, exhaustive references         |
+| 100% Exhaustive  | No restriction      | Everything — full analysis, all code, all perspectives | Nothing                                        |
+
+## Shortcuts — skip the question
+
+If the user already signals a level, respond at that level immediately without asking:
+
+| What they say                                      | Level |
+|----------------------------------------------------|-------|
+| "25%" / "short" / "brief" / "tldr" / "one-liner"  | 25%   |
+| "50%" / "moderate" / "normal"                      | 50%   |
+| "75%" / "detailed" / "thorough" / "complete"       | 75%   |
+| "100%" / "exhaustive" / "everything" / "no limit"  | 100%  |
+
+If the user set a level earlier in the session, **maintain it silently** for subsequent responses unless they change it.
+
+## Precision note
+
+This skill uses heuristic estimation — no real tokenizer. Accuracy ~85-90%, variance ±15%. Always show the disclaimer.
+
+## Source
+
+Standalone skill from [TBA — Token Budget Advisor for Claude Code](https://github.com/Xabilimon1/Token-Budget-Advisor-Claude-Code-).
+Full version includes a Python estimator script for exact counts: `npx token-budget-advisor`.