The Completionist's Handbook — How to Collect All 18 Species and Document Your Buddy Zoo

You've hatched your first buddy. Maybe it's a Common Duck, maybe a Rare Ghost. Either way, you've seen the species catalog — 18 creatures, each with its own ASCII sprite, backstory, and personality. And now a question gnaws at you: what would I get with a different UUID?

That question is the collector's itch, and it has a formal name in mathematics: the Coupon Collector's Problem. First studied by Euler and formalized by Flajolet in 1992, it asks a deceptively simple question: if you draw randomly from n equally likely items, how many draws until you've seen every item at least once?

For Claude Buddy, n = 18. The species roll is a uniform pick from the SPECIES array — every species has exactly 1/18 ≈ 5.56% probability, regardless of rarity. This means the math is clean, the simulations are precise, and the strategy is real. Let's build your zoo.

The expected number of trials to collect all n equally likely coupons is:

E(T) = n × H(n)

where H(n) is the n-th harmonic number: H(n) = 1 + 1/2 + 1/3 + … + 1/n.

For 18 species: H(18) = 3.4951, so E(T) = 18 × 3.4951 ≈ 63 trials. The standard deviation is approximately 23, meaning most collectors will finish between 40 and 86 trials.

The intuition is beautiful: your first species is guaranteed (1 trial). The second requires 18/17 ≈ 1.06 trials on average. But the last species — when you already have 17 — requires 18/1 = 18 trials on average. That final holdout is where patience is tested.

Species #	Already Collected	Probability of New	Expected Trials	Cumulative Expected
1st	0	18/18 = 100%	1.0	1.0
2nd	1	17/18 = 94.4%	1.06	2.06
5th	4	14/18 = 77.8%	1.29	5.56
10th	9	9/18 = 50.0%	2.00	14.69
15th	14	4/18 = 22.2%	4.50	33.19
17th	16	2/18 = 11.1%	9.00	45.94
18th	17	1/18 = 5.56%	18.00	63.94

Notice how the last three species alone account for 30 of the 64 expected trials. This is the collector's curse: the closer you get, the slower it feels.

Theory is elegant, but we ran 100,000 Monte Carlo simulations to get the exact probability distribution. Here are the milestone numbers every collector needs:

Milestone	Trials Needed	Meaning
Minimum observed	21	Luckiest possible (top 0.01%)
25th percentile	49	1 in 4 collectors finish by here
Median (50%)	59	Half of all collectors finish by here
Mean	63	Mathematical expected value
75th percentile	73	3 in 4 collectors finish by here
90th percentile	91	Only 10% need more than this
95th percentile	103	Unlucky but not impossible
99th percentile	131	Extremely unlucky
Maximum observed	299	Worst case in 100k sims

Key takeaway: if you've tried 100 UUIDs and still haven't found all 18, you're in the unluckiest 5%. But you're not broken — the algorithm is working exactly as expected. Keep going.

Not every collector has the same goal. We've defined five tiers of increasing ambition, each with its own math and strategy:

Tier	Goal	Target Count	Expected Trials	90% Confidence
🌱 Explorer	See 9 of 18 species (50%)	9	~22	~30
📦 Collector	All 18 species (any rarity)	18	~63	~91
⭐ Rarity Hunter	All 5 rarity tiers	5	~106	~231
💎 Combo Seeker	All 90 species × rarity combos	90	~9,000+	~15,000+
✨ Shiny Completionist	At least one shiny of each species	18 shinies	~115,000+	~180,000+

The jump between tiers is exponential. Going from Collector to Rarity Hunter roughly doubles your effort. Going from Rarity Hunter to Combo Seeker multiplies it by 40×. And Shiny Completionist? That's a lifetime project — each shiny-species combo has only a 1/1,800 chance per trial.

The most efficient collection strategy is a systematic sweep using the Buddy Checker at claudebuddy.art. Here's the method:

1. Start with any string. Type "test-001", "test-002", "test-003" into the checker. Each string produces a deterministic buddy.
2. Log every result. Create a spreadsheet with columns: Input String, Species, Rarity, Shiny, Hat, Eye. The checker shows all of these instantly.
3. Track your gaps. After 30 trials, you'll likely have 13-14 species. Identify the missing ones.
4. Keep going until 18/18. The last 2-3 species will take the most patience. Don't change your naming scheme — just increment.

Why the Buddy Checker? Because it uses the exact same algorithm as Claude Code: FNV-1a hash → Mulberry32 PRNG → sequential rolls. Every result you see on the website is mathematically identical to what /buddy would produce. You can check hundreds of UUIDs in minutes without touching Claude Code.

For the programmatically inclined, you can write a script that runs the buddy engine against thousands of inputs. The algorithm is public and deterministic:

// Pseudocode for species collection sweep
const collected = new Set();
let trials = 0;
while (collected.size < 18) {
  const uuid = `collector-sweep-${trials}`;
  const buddy = rollBuddy(uuid);
  collected.add(buddy.species);
  trials++;
  if (!seen[buddy.species]) {
    console.log(`NEW: ${buddy.species} found at trial ${trials}`);
  }
}
console.log(`All 18 collected in ${trials} trials`);COPY

In our tests, this approach consistently finds all 18 species in 50-80 trials, matching the theoretical prediction. The script can also log rarity, shiny status, and hat for each find, building your complete zoo database automatically.

Pro tip: Use a prefix that means something to you. "alice-001", "bob-001", or even dates like "2026-04-16-001". Each input is a permanent, reproducible identity — you can always re-check it later.

If your goal extends beyond species to rarity tiers, the math changes dramatically. Species are uniformly distributed (1/18 each), but rarities are heavily skewed:

Rarity	Weight	Probability	Expected Trials for First
Common	60	60%	1.67
Uncommon	25	25%	4.00
Rare	10	10%	10.00
Epic	4	4%	25.00
Legendary	1	1%	100.00

Our 100,000 simulations for collecting all 5 rarities show:

• Median: 75 trials (half finish by here)
• Mean: 106 trials (skewed by legendary bottleneck)
• 90th percentile: 231 trials
• 99th percentile: 463 trials

The bottleneck is always Legendary. You'll likely collect Common, Uncommon, Rare, and Epic within your first 30 trials. Then you'll spend 70+ more trials waiting for that 1% Legendary to appear. This is normal — the math demands it.

A true completionist doesn't just collect — they document. Here's how to build your personal Buddy Zoo:

The Zoo Spreadsheet: Create a grid with 18 rows (species) and 5 columns (rarities). Each cell records the UUID that produced that combination. Mark shiny variants with a star. This becomes your permanent collection record.

Species	Common	Uncommon	Rare	Epic	Legendary
Duck	test-003 ✓	test-047 ✓	—	—	—
Cat	test-011 ✓	—	test-089 ✓	—	—
Dragon	—	test-022 ✓	—	test-156 ✓	—
…	…	…	…	…	…

The Share Card: Use the Buddy Checker's built-in share card feature to generate a 1200×630 image of your best finds. Post them to the community with the UUID so others can verify.

The Verification Principle: Every entry in your zoo is independently verifiable. Anyone can type the same UUID into the Buddy Checker and confirm your claim. This is the beauty of deterministic systems — there's no faking a Legendary Shiny Dragon.

Every collector hits the same wall: 17 out of 18 species found, and the last one refuses to appear. This is mathematically inevitable — the expected wait for that final species is 18 trials, but the variance is high. You might get lucky in 5 tries, or you might need 50.

Here's the probability of finding your last species within k additional trials:

Additional Trials	Probability of Finding It
5	24.5%
10	43.0%
18	63.2%
30	81.3%
50	93.8%
80	98.9%

The formula is simple: P(find within k trials) = 1 − (17/18)^k. Each trial has a 5.56% chance, and the attempts are independent. If you've been stuck for 30 tries, the next trial still has exactly 5.56% odds — the universe doesn't owe you a catch-up.

This is the gambler's fallacy in action. The only real strategy is patience and volume. Keep incrementing your UUID counter, and the math will deliver.

The buddy engine is deterministic, the math is known, and the tools are free. Whether you're aiming for a casual 18-species sweep or the insane 90-combo grid, the path is clear:

1. Open the Buddy Checker and start entering strings
2. Log every result in your zoo spreadsheet
3. Track your progress against the milestone table
4. Share your rarest finds using the share card feature
5. Explore the Species Catalog to see what you're still missing

Remember: the median collector finishes all 18 species in just 59 trials. That's less than an hour with the Buddy Checker. Your zoo is waiting — go build it.