Add level 10: Vault Ledger (dynamic values)

`vault:` with four entries — decimal int gold, decimal int silver,
fractional float experience, and an ISO-8601 date string. Description
hints at hex/octal/exponent equivalents the player can write — any
form parsing to the same numeric value passes.

All four values randomised per seed (ChaCha8Rng XOR'd with 0x..0A).

Not wired into levels::registry() yet — integration belongs to a follow-up.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/levels/l08_tags.rs

@@ -1,111 +0,0 @@
-//! Level 8 — tags and newlines. The scroll preserves its lines and
-//! demands explicit types.
-//!
-//! Paired design note: `l08.md`.
-//!
-//! The target value uses:
-//! - a multi-line string for `scroll:` (block scalar `|` round-trips through
-//!   serde_yaml as a `Value::String` with embedded newlines),
-//! - a fractional float for `weight:` (forces float type without needing the
-//!   `!!float` tag in the target text — but the player can use either),
-//! - a string of digits for `title:` (player needs quotes or `!!str` to
-//!   avoid the integer interpretation).
-
-use rand::seq::SliceRandom;
-use rand::{Rng, SeedableRng};
-use rand_chacha::ChaCha8Rng;
-use serde::Serialize;
-use serde_yaml::{Mapping, Value};
-
-use crate::describe::Describer;
-
-use super::{Generated, Level};
-
-pub struct Tags;
-
-const VERBS: &[&str] = &["Beware", "Avoid", "Heed", "Mark"];
-const NOUNS: &[&str] = &[
-    "the path that turns twice",
-    "the third spring",
-    "the silent statue",
-    "the moonlit door",
-];
-const TITLES: &[&str] = &["1024", "2048", "4096", "8192"];
-
-#[derive(Serialize)]
-struct DescCtx {
-    scroll_lines: Vec<String>,
-    weight: f64,
-    title: String,
-}
-
-impl Level for Tags {
-    fn id(&self) -> u8 {
-        8
-    }
-
-    fn name(&self) -> &'static str {
-        "Scroll of Tags"
-    }
-
-    fn generate(&self, seed: u64) -> Generated {
-        let mut rng = ChaCha8Rng::seed_from_u64(seed ^ 0x0000_0000_0000_0008);
-
-        let line_n = 2;
-        let scroll_lines: Vec<String> = (0..line_n)
-            .map(|_| {
-                let v = VERBS.choose(&mut rng).unwrap();
-                let n = NOUNS.choose(&mut rng).unwrap();
-                format!("{v} {n}.")
-            })
-            .collect();
-        // Block scalar `|` produces a string ending in `\n` after the last line.
-        let scroll_text = format!("{}\n", scroll_lines.join("\n"));
-
-        // Fractional weight so serde_yaml's float serialisation keeps the
-        // `.5` and matches the player's submission unambiguously.
-        let weight = rng.gen_range(1..=20) as f64 + 0.5;
-        let title = TITLES.choose(&mut rng).unwrap().to_string();
-
-        let mut top = Mapping::new();
-        top.insert(
-            Value::String("scroll".to_string()),
-            Value::String(scroll_text),
-        );
-        top.insert(Value::String("weight".to_string()), Value::from(weight));
-        top.insert(
-            Value::String("title".to_string()),
-            Value::String(title.clone()),
-        );
-
-        let target_yaml =
-            serde_yaml::to_string(&Value::Mapping(top)).expect("serialise mapping");
-
-        let mut d = Describer::new();
-        d.register(
-            "l08",
-            "A scroll demands its types. Match exactly:\n\
-             scroll: multi-line text{% for line in scroll_lines %}\n  {{ line }}{% endfor %}\n\
-             weight: must parse as the float {{ weight }}\n\
-             title:  must parse as the string \"{{ title }}\"\n\
-             💡 Block scalar `|` preserves newlines; `!!str` (or quotes) forces a digit-only string.",
-        )
-        .expect("register template");
-        let description = d
-            .render(
-                "l08",
-                &DescCtx {
-                    scroll_lines,
-                    weight,
-                    title,
-                },
-            )
-            .expect("render template");
-
-        Generated {
-            target_yaml,
-            description,
-            flavor: "📜 An ancient scroll insists on its precise form.".to_string(),
-        }
-    }
-}

src/levels/l10_dynamic.rs

@@ -0,0 +1,101 @@
+//! Level 10 — dynamic values. The vault ledger accepts numbers and
+//! dates in many forms.
+//!
+//! Paired design note: `l10.md`.
+//!
+//! The target is canonical (decimal ints, decimal float, ISO date
+//! string). The lesson is that the player can write equivalent values
+//! in hex / octal / exponent forms — all parse to the same number.
+
+use rand::{Rng, SeedableRng};
+use rand_chacha::ChaCha8Rng;
+use serde::Serialize;
+use serde_yaml::{Mapping, Value};
+
+use crate::describe::Describer;
+
+use super::{Generated, Level};
+
+pub struct Dynamic;
+
+#[derive(Serialize)]
+struct DescCtx {
+    gold_dec: i64,
+    gold_hex: String,
+    silver_dec: i64,
+    silver_oct: String,
+    experience: f64,
+    date: String,
+}
+
+impl Level for Dynamic {
+    fn id(&self) -> u8 {
+        10
+    }
+
+    fn name(&self) -> &'static str {
+        "Vault Ledger"
+    }
+
+    fn generate(&self, seed: u64) -> Generated {
+        let mut rng = ChaCha8Rng::seed_from_u64(seed ^ 0x0000_0000_0000_000A);
+
+        let gold = rng.gen_range(0x100..=0xFFFi64);
+        let silver = rng.gen_range(0o100..=0o777i64);
+        // Fractional float so the canonical serialisation keeps the `.5`.
+        let experience = rng.gen_range(10..=99) as f64 + 0.5;
+        let year = rng.gen_range(1100..=2050i64);
+        let month = rng.gen_range(1..=12i64);
+        let day = rng.gen_range(1..=28i64);
+        let date = format!("{year:04}-{month:02}-{day:02}");
+
+        let mut vault = Mapping::new();
+        vault.insert(Value::String("gold".to_string()), Value::from(gold));
+        vault.insert(Value::String("silver".to_string()), Value::from(silver));
+        vault.insert(
+            Value::String("experience".to_string()),
+            Value::from(experience),
+        );
+        vault.insert(
+            Value::String("date".to_string()),
+            Value::String(date.clone()),
+        );
+
+        let mut top = Mapping::new();
+        top.insert(Value::String("vault".to_string()), Value::Mapping(vault));
+
+        let target_yaml =
+            serde_yaml::to_string(&Value::Mapping(top)).expect("serialise mapping");
+
+        let mut d = Describer::new();
+        d.register(
+            "l10",
+            "The vault ledger demands its values:\n\
+             gold:       {{ gold_dec }}   (try hex: 0x{{ gold_hex }})\n\
+             silver:     {{ silver_dec }} (try octal: 0o{{ silver_oct }})\n\
+             experience: {{ experience }} (any equivalent float form passes)\n\
+             date:       {{ date }}        (an ISO-8601 date string)\n\
+             💡 Any equivalent numeric form passes — what matters is the parsed value.",
+        )
+        .expect("register template");
+        let description = d
+            .render(
+                "l10",
+                &DescCtx {
+                    gold_dec: gold,
+                    gold_hex: format!("{:X}", gold),
+                    silver_dec: silver,
+                    silver_oct: format!("{:o}", silver),
+                    experience,
+                    date,
+                },
+            )
+            .expect("render template");
+
+        Generated {
+            target_yaml,
+            description,
+            flavor: "🪙 A vault ledger awaits in many ciphers.".to_string(),
+        }
+    }
+}

src/levels/mod.rs

@@ -13,7 +13,7 @@
 pub mod l01_minimum;
 pub mod l02_kv;
 pub mod l03_dict;
-pub mod l08_tags;
+pub mod l10_dynamic;
 
 use serde::{Deserialize, Serialize};