diff --git a/crates/workshop-rs-cli/src/census.rs b/crates/workshop-rs-cli/src/census.rs
index aa69a38..a48eb7c 100644
--- a/crates/workshop-rs-cli/src/census.rs
+++ b/crates/workshop-rs-cli/src/census.rs
@@ -816,6 +816,7 @@ fn settings_probe(definition: &SettingDefinition, catalog: &Catalog) -> String {
             lines.push(format!("{indent}{name} {{"));
             lines.push(format!("{indent}}}"));
         }
+        other => unreachable!("census has no probe for settings value domain {other:?}"),
     }
     while depth > 1 {
         depth -= 1;
diff --git a/crates/workshop-rs-cli/src/lib.rs b/crates/workshop-rs-cli/src/lib.rs
index 9c6a82e..045ce5d 100644
--- a/crates/workshop-rs-cli/src/lib.rs
+++ b/crates/workshop-rs-cli/src/lib.rs
@@ -229,9 +229,8 @@ fn emit_command(args: Vec<String>) -> i32 {
             return 1;
         }
     };
-    let options = EmitOptions {
-        fallback_locale: fallback,
-    };
+    let mut options = EmitOptions::default();
+    options.fallback_locale = fallback;
     match emitter::emit_with_options(&program, &catalog, &locale, &options) {
         Ok(output) => {
             report_fallbacks(&output.fallback_ids);
@@ -283,9 +282,8 @@ fn convert_command(args: Vec<String>) -> i32 {
             return 1;
         }
     };
-    let options = ConvertOptions {
-        fallback_locale: fallback,
-    };
+    let mut options = ConvertOptions::default();
+    options.fallback_locale = fallback;
     match convert::convert(&input, &catalog, &from, &to, &options) {
         Ok(output) => {
             report_fallbacks(&output.fallback_ids);
diff --git a/crates/workshop-rs/src/actions/layout.rs b/crates/workshop-rs/src/actions/layout.rs
index 4581b15..9651e96 100644
--- a/crates/workshop-rs/src/actions/layout.rs
+++ b/crates/workshop-rs/src/actions/layout.rs
@@ -14,6 +14,7 @@ pub struct ActionLayout {
 
 /// Errors returned while querying public canonical native action layout.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum ActionLayoutError {
     /// The public program cannot be materialized as a valid Workshop program.
     InvalidProgram { message: String },
diff --git a/crates/workshop-rs/src/analysis/element_count.rs b/crates/workshop-rs/src/analysis/element_count.rs
index 53cbc25..5cfa25b 100644
--- a/crates/workshop-rs/src/analysis/element_count.rs
+++ b/crates/workshop-rs/src/analysis/element_count.rs
@@ -25,6 +25,7 @@ pub enum ElementNodeKind {
 
 /// One node's contribution and its nested element-count analysis.
 #[derive(Debug, Clone)]
+#[non_exhaustive]
 pub struct ElementCountNode {
     pub kind: ElementNodeKind,
     /// An opaque identity unique within this report. It is not a WIR or
@@ -47,6 +48,7 @@ pub struct ElementCountNode {
 
 /// A structured element-count report for one canonical Workshop program.
 #[derive(Debug, Clone)]
+#[non_exhaustive]
 pub struct ElementCountReport {
     /// The sum of all rule counts.
     pub total: usize,
@@ -65,6 +67,7 @@ impl ElementCountReport {
 
 /// A construct for which an exact canonical element count cannot be produced.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum ElementCountError {
     /// The input cannot be materialized or structurally validated as a
     /// canonical Workshop program.
diff --git a/crates/workshop-rs/src/analysis/semantic.rs b/crates/workshop-rs/src/analysis/semantic.rs
index 1abff75..6e164b8 100644
--- a/crates/workshop-rs/src/analysis/semantic.rs
+++ b/crates/workshop-rs/src/analysis/semantic.rs
@@ -60,6 +60,7 @@ impl ResidualClassification {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub struct SemanticIssue {
     pub kind: IncompletenessKind,
     pub name: String,
diff --git a/crates/workshop-rs/src/catalog/detect.rs b/crates/workshop-rs/src/catalog/detect.rs
index 14ec871..2ac835a 100644
--- a/crates/workshop-rs/src/catalog/detect.rs
+++ b/crates/workshop-rs/src/catalog/detect.rs
@@ -3,6 +3,7 @@ use crate::core::error::{Result, WorkshopError};
 
 /// A language-detection result with ranked evidence.
 #[derive(Debug, Clone, PartialEq)]
+#[non_exhaustive]
 pub struct Detection {
     /// The best-matching locale.
     pub locale: Locale,
diff --git a/crates/workshop-rs/src/catalog/mod.rs b/crates/workshop-rs/src/catalog/mod.rs
index 91e8bc7..8e172d1 100644
--- a/crates/workshop-rs/src/catalog/mod.rs
+++ b/crates/workshop-rs/src/catalog/mod.rs
@@ -111,6 +111,7 @@ impl Kind {
 /// vectors, or null.
 #[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct ParamCoercions {
     /// Accept `False` as numeric zero.
     #[serde(default)]
@@ -351,6 +352,7 @@ impl EnumDomain {
 
 /// Target-format metadata recorded in the catalog.
 #[derive(Debug, Clone, PartialEq, Eq, Deserialize, Serialize)]
+#[non_exhaustive]
 pub struct TargetMeta {
     pub game: String,
     pub format: String,
@@ -360,6 +362,7 @@ pub struct TargetMeta {
 /// Provenance of the catalog data.
 #[derive(Debug, Clone, PartialEq, Eq, Deserialize, Serialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct Provenance {
     pub generator: String,
     pub generator_version: String,
@@ -376,6 +379,7 @@ pub struct Provenance {
 /// localized preset identities, and enum members) carry a mapping for the
 /// locale out of the declared total.
 #[derive(Debug, Clone, PartialEq, Eq, Deserialize, Serialize)]
+#[non_exhaustive]
 pub struct LocaleCoverage {
     pub locale: Locale,
     /// Canonical entries with a declared mapping in this locale.
@@ -391,6 +395,7 @@ pub struct LocaleCoverage {
 /// identity names.
 #[derive(Debug, Clone, PartialEq, Eq, Deserialize, Serialize)]
 #[serde(rename_all = "kebab-case")]
+#[non_exhaustive]
 pub struct CatalogIdentity {
     /// The `workshop-rs` package version (semver); bumped by code changes.
     pub implementation_version: String,
diff --git a/crates/workshop-rs/src/core/error.rs b/crates/workshop-rs/src/core/error.rs
index cf95189..59444e6 100644
--- a/crates/workshop-rs/src/core/error.rs
+++ b/crates/workshop-rs/src/core/error.rs
@@ -5,6 +5,7 @@ use crate::core::source::Span;
 
 /// A structured Workshop-language error.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum WorkshopError {
     /// Catalog data is malformed or fails validation.
     Catalog(CatalogError),
@@ -33,6 +34,7 @@ pub enum WorkshopError {
 
 /// Catalog-specific error.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub struct CatalogError {
     pub code: &'static str,
     pub message: String,
diff --git a/crates/workshop-rs/src/core/source.rs b/crates/workshop-rs/src/core/source.rs
index 2d3c38e..60d37a0 100644
--- a/crates/workshop-rs/src/core/source.rs
+++ b/crates/workshop-rs/src/core/source.rs
@@ -231,6 +231,7 @@ impl SourceEdit {
 
 /// Failure while creating or applying source edits.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum SourceEditError {
     InvalidRange,
     SourceMismatch,
diff --git a/crates/workshop-rs/src/gameplay/mod.rs b/crates/workshop-rs/src/gameplay/mod.rs
index b1f5e2e..fffba88 100644
--- a/crates/workshop-rs/src/gameplay/mod.rs
+++ b/crates/workshop-rs/src/gameplay/mod.rs
@@ -277,6 +277,7 @@ impl LocalizedText {
 /// A machine-identifiable source reference for a gameplay fact.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct SourceReference {
     pub source: String,
     pub locator: String,
@@ -284,10 +285,25 @@ pub struct SourceReference {
     pub note: Option<String>,
 }
 
+impl SourceReference {
+    pub fn new(source: impl Into<String>, locator: impl Into<String>) -> Self {
+        Self {
+            source: source.into(),
+            locator: locator.into(),
+            note: None,
+        }
+    }
+    pub fn with_note(mut self, note: impl Into<String>) -> Self {
+        self.note = Some(note.into());
+        self
+    }
+}
+
 /// Identity and source metadata of a gameplay dataset. This is distinct from
 /// the Workshop parser/catalog dataset identity.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
+#[non_exhaustive]
 pub struct GameplayDatasetIdentity {
     pub dataset_id: String,
     pub version: String,
@@ -298,6 +314,28 @@ pub struct GameplayDatasetIdentity {
     pub reviewed: bool,
 }
 
+impl GameplayDatasetIdentity {
+    pub fn new(
+        dataset_id: impl Into<String>,
+        version: impl Into<String>,
+        digest: impl Into<String>,
+        source: impl Into<String>,
+        license: impl Into<String>,
+        target: impl Into<String>,
+        reviewed: bool,
+    ) -> Self {
+        Self {
+            dataset_id: dataset_id.into(),
+            version: version.into(),
+            digest: digest.into(),
+            source: source.into(),
+            license: license.into(),
+            target: target.into(),
+            reviewed,
+        }
+    }
+}
+
 /// A gameplay fact tied to source references in the dataset version being consumed.
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct Fact<T> {
@@ -537,6 +575,7 @@ impl Hero {
 
 /// Explicit failure for a logical-slot lookup.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum AbilityLookupError {
     Missing {
         hero: HeroId,
@@ -583,6 +622,7 @@ impl std::error::Error for AbilityLookupError {}
 
 /// Validation and construction errors for gameplay data.
 #[derive(Debug, Clone, PartialEq)]
+#[non_exhaustive]
 pub enum GameplayDataError {
     EmptyIdentity(&'static str),
     DuplicateHero(HeroId),
diff --git a/crates/workshop-rs/src/gameplay/query.rs b/crates/workshop-rs/src/gameplay/query.rs
index e83b0a5..de92317 100644
--- a/crates/workshop-rs/src/gameplay/query.rs
+++ b/crates/workshop-rs/src/gameplay/query.rs
@@ -22,6 +22,7 @@ pub enum StatOwner {
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum GameplayQueryError {
     MissingHero {
         hero: HeroId,
@@ -93,6 +94,7 @@ impl std::error::Error for GameplayQueryError {}
 
 /// Explicit failures from locale-aware display-name resolution.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum AbilityNameResolutionError {
     MissingHero {
         hero: HeroId,
@@ -203,6 +205,7 @@ impl TryFrom<f64> for CooldownPercentage {
 }
 
 #[derive(Debug, Clone, PartialEq)]
+#[non_exhaustive]
 pub enum CooldownPercentageError {
     NotFinite { value: f64 },
     OutOfRange { value: f64 },
@@ -228,6 +231,7 @@ pub enum CooldownNonApplicability {
 }
 
 #[derive(Debug, Clone, PartialEq)]
+#[non_exhaustive]
 pub enum CooldownError {
     Missing {
         ability: AbilityRef,
diff --git a/crates/workshop-rs/src/output/convert.rs b/crates/workshop-rs/src/output/convert.rs
index 93f0f46..295b28c 100644
--- a/crates/workshop-rs/src/output/convert.rs
+++ b/crates/workshop-rs/src/output/convert.rs
@@ -16,6 +16,7 @@ use crate::output::emitter::{self, EmitOptions};
 
 /// Conversion options: opt-in fallback for missing target-locale mappings.
 #[derive(Debug, Clone, Default, PartialEq, Eq)]
+#[non_exhaustive]
 pub struct ConvertOptions {
     /// When a canonical identity has no spelling for the target locale, its
     /// spelling in this declared locale is used instead. `None` (the
@@ -26,6 +27,7 @@ pub struct ConvertOptions {
 
 /// The result of a raw Workshop locale conversion.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub struct Conversion {
     /// The converted localized Workshop text.
     pub text: String,
diff --git a/crates/workshop-rs/src/output/emitter.rs b/crates/workshop-rs/src/output/emitter.rs
index 51736bb..c79d6ce 100644
--- a/crates/workshop-rs/src/output/emitter.rs
+++ b/crates/workshop-rs/src/output/emitter.rs
@@ -19,6 +19,7 @@ pub(crate) use crate::wir;
 
 /// Emission options: opt-in fallback for missing target-locale mappings.
 #[derive(Debug, Clone, Default, PartialEq, Eq)]
+#[non_exhaustive]
 pub struct EmitOptions {
     /// When a canonical identity has no spelling for the target locale, its
     /// spelling in this declared locale is used instead. `None` (the default)
@@ -29,6 +30,7 @@ pub struct EmitOptions {
 
 /// The result of a localized emission.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub struct EmitOutput {
     /// The emitted localized Workshop text.
     pub text: String,
diff --git a/crates/workshop-rs/src/output/roundtrip.rs b/crates/workshop-rs/src/output/roundtrip.rs
index 5862c13..c8ec278 100644
--- a/crates/workshop-rs/src/output/roundtrip.rs
+++ b/crates/workshop-rs/src/output/roundtrip.rs
@@ -14,6 +14,7 @@ use crate::output::emitter;
 
 /// A recorded round-trip result for regression and contract checks.
 #[derive(Debug, Clone, PartialEq)]
+#[non_exhaustive]
 pub struct RoundTripRecord {
     /// SHA-256 of the input Workshop text.
     pub input_identity: String,
diff --git a/crates/workshop-rs/src/program.rs b/crates/workshop-rs/src/program.rs
index 88284ed..6b38fe0 100644
--- a/crates/workshop-rs/src/program.rs
+++ b/crates/workshop-rs/src/program.rs
@@ -51,6 +51,7 @@ struct ActionProvenance {
 
 /// A failure while attaching source mappings to a public [`Program`].
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum SourceMappingError {
     UnknownFile(FileId),
     InvalidSpan(Span),
diff --git a/crates/workshop-rs/src/program/source_map.rs b/crates/workshop-rs/src/program/source_map.rs
index c873711..dd82e5b 100644
--- a/crates/workshop-rs/src/program/source_map.rs
+++ b/crates/workshop-rs/src/program/source_map.rs
@@ -34,6 +34,7 @@ pub struct SourceMap {
 /// Workshop text together with the [`SourceMap`] of its authored origin: the
 /// `workshop-rs/mapped-text-v1` artifact.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub struct MappedText {
     /// The Workshop text, itself a `workshop-rs/text-v1` artifact.
     pub text: String,
@@ -411,6 +412,13 @@ impl SourceMap {
 }
 
 impl MappedText {
+    pub fn new(text: impl Into<String>, map: SourceMap) -> Self {
+        Self {
+            text: text.into(),
+            map,
+        }
+    }
+
     /// Serialize as a `workshop-rs/mapped-text-v1` JSON document.
     pub fn to_json(&self) -> String {
         let artifact = Artifact {
diff --git a/crates/workshop-rs/src/settings/schema.rs b/crates/workshop-rs/src/settings/schema.rs
index 05a4ac0..fccf033 100644
--- a/crates/workshop-rs/src/settings/schema.rs
+++ b/crates/workshop-rs/src/settings/schema.rs
@@ -48,6 +48,7 @@ pub enum SettingIdentity {
 
 /// The Workshop-native section that owns a setting.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+#[non_exhaustive]
 pub enum SettingScope {
     Main,
     Lobby,
@@ -123,6 +124,7 @@ pub enum Applicability {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum NumericBoundsError {
     NonFinite,
     Reversed,
@@ -196,6 +198,7 @@ pub struct EffectiveNumber {
 
 /// The machine-readable value domain of a setting.
 #[derive(Debug, Clone, PartialEq, PartialOrd)]
+#[non_exhaustive]
 pub enum SettingValueDomain {
     Boolean,
     Number(NumericBounds),
@@ -288,6 +291,7 @@ impl SettingSourceEdit {
 
 /// Failure from a typed settings query or source-preserving edit.
 #[derive(Debug, Clone, PartialEq)]
+#[non_exhaustive]
 pub enum SettingOperationError {
     NotApplicable {
         setting: SettingId,
@@ -389,6 +393,7 @@ impl SettingPresentation {
 
 /// Source metadata shared by the reviewed table projection.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[non_exhaustive]
 pub struct SettingSource {
     pub kind: SettingSourceKind,
     pub source: &'static str,
diff --git a/crates/workshop-rs/tests/gameplay.rs b/crates/workshop-rs/tests/gameplay.rs
index 169cb9e..fb9766b 100644
--- a/crates/workshop-rs/tests/gameplay.rs
+++ b/crates/workshop-rs/tests/gameplay.rs
@@ -5,11 +5,7 @@ use workshop_rs::gameplay::{
 };
 
 fn source_reference(locator: &str) -> SourceReference {
-    SourceReference {
-        source: "workshop-data".to_string(),
-        locator: locator.to_string(),
-        note: None,
-    }
+    SourceReference::new("workshop-data", locator)
 }
 
 fn names(name: &str, locator: &str) -> Fact<LocalizedText> {
@@ -38,15 +34,15 @@ fn hero(id: &str, abilities: Vec<Ability>) -> Hero {
 }
 
 fn identity() -> GameplayDatasetIdentity {
-    GameplayDatasetIdentity {
-        dataset_id: "overwatch-workshop-hero-gameplay".to_string(),
-        version: "2026-08-12".to_string(),
-        digest: "sha256:test".to_string(),
-        source: "workshop-data@d854bf01fc7bbf3b2169f67408c07a8da8989ad6".to_string(),
-        license: "MIT-compatible user-provided export".to_string(),
-        target: "Overwatch Workshop hero identity and gameplay facts".to_string(),
-        reviewed: true,
-    }
+    GameplayDatasetIdentity::new(
+        "overwatch-workshop-hero-gameplay",
+        "2026-08-12",
+        "sha256:test",
+        "workshop-data@d854bf01fc7bbf3b2169f67408c07a8da8989ad6",
+        "MIT-compatible user-provided export",
+        "Overwatch Workshop hero identity and gameplay facts",
+        true,
+    )
 }
 
 #[test]
@@ -238,11 +234,7 @@ fn empty_id_and_empty_sources_are_rejected() {
         HeroId::new("ana"),
         Fact::new(
             LocalizedText::new([("en-US".to_string(), "Ana".to_string())]),
-            vec![SourceReference {
-                source: String::new(),
-                locator: "heroes.ana".to_string(),
-                note: None,
-            }],
+            vec![SourceReference::new("", "heroes.ana")],
         ),
         vec![],
         vec![source_reference("heroes.ana")],
diff --git a/crates/workshop-rs/tests/gameplay_data.rs b/crates/workshop-rs/tests/gameplay_data.rs
index 5437185..15b2215 100644
--- a/crates/workshop-rs/tests/gameplay_data.rs
+++ b/crates/workshop-rs/tests/gameplay_data.rs
@@ -10,11 +10,7 @@ const SOURCE: &str = "workshop-data/workshop-data.json@d854bf01fc7bbf3b2169f6740
 const OFFICIAL_HERO_SOURCE: &str = "Blizzard Entertainment official Overwatch hero detail";
 
 fn source_reference(locator: &str) -> SourceReference {
-    SourceReference {
-        source: SOURCE.to_string(),
-        locator: locator.to_string(),
-        note: Some("commitDate=2026-08-12".to_string()),
-    }
+    SourceReference::new(SOURCE, locator).with_note("commitDate=2026-08-12")
 }
 
 fn names(name: &str, locator: &str) -> Fact<LocalizedText> {
@@ -25,15 +21,15 @@ fn names(name: &str, locator: &str) -> Fact<LocalizedText> {
 }
 
 fn identity() -> GameplayDatasetIdentity {
-    GameplayDatasetIdentity {
-        dataset_id: "test-gameplay".to_string(),
-        version: "test".to_string(),
-        digest: "sha256:test".to_string(),
-        source: SOURCE.to_string(),
-        license: "MIT-compatible test data".to_string(),
-        target: "test".to_string(),
-        reviewed: true,
-    }
+    GameplayDatasetIdentity::new(
+        "test-gameplay",
+        "test",
+        "sha256:test",
+        SOURCE,
+        "MIT-compatible test data",
+        "test",
+        true,
+    )
 }
 
 fn assert_sources(sources: &[SourceReference], source: &str, locator: &str) {
diff --git a/crates/workshop-rs/tests/gameplay_query.rs b/crates/workshop-rs/tests/gameplay_query.rs
index 4ace709..20a0c21 100644
--- a/crates/workshop-rs/tests/gameplay_query.rs
+++ b/crates/workshop-rs/tests/gameplay_query.rs
@@ -10,11 +10,7 @@ use workshop_rs::gameplay::{
 };
 
 fn source_reference(locator: &str) -> SourceReference {
-    SourceReference {
-        source: "test-fixture".to_string(),
-        locator: locator.to_string(),
-        note: None,
-    }
+    SourceReference::new("test-fixture", locator)
 }
 
 fn names(en: &str, zh: &str, locator: &str) -> Fact<LocalizedText> {
@@ -41,15 +37,15 @@ fn seconds(value: f64) -> Quantity {
 }
 
 fn identity() -> GameplayDatasetIdentity {
-    GameplayDatasetIdentity {
-        dataset_id: "gameplay-test".to_string(),
-        version: "2026-08-18".to_string(),
-        digest: "sha256:test".to_string(),
-        source: "test-fixture".to_string(),
-        license: "MIT".to_string(),
-        target: "gameplay query tests".to_string(),
-        reviewed: true,
-    }
+    GameplayDatasetIdentity::new(
+        "gameplay-test",
+        "2026-08-18",
+        "sha256:test",
+        "test-fixture",
+        "MIT",
+        "gameplay query tests",
+        true,
+    )
 }
 
 fn catalog() -> GameplayCatalog {
diff --git a/crates/workshop-rs/tests/public_api.rs b/crates/workshop-rs/tests/public_api.rs
index ff31b2a..089e685 100644
--- a/crates/workshop-rs/tests/public_api.rs
+++ b/crates/workshop-rs/tests/public_api.rs
@@ -1,6 +1,8 @@
 use workshop_rs::catalog::{Catalog, Locale};
 use workshop_rs::settings::{PathPart, schema};
-use workshop_rs::{Action, Event, Program, Rule, Value, emitter, parser, roundtrip, rules};
+use workshop_rs::{
+    Action, Event, MappedText, Program, Rule, SourceMap, Value, emitter, parser, roundtrip, rules,
+};
 
 #[test]
 fn canonical_program_operations_cover_parse_validate_inspect_emit_and_roundtrip() {
@@ -122,3 +124,24 @@ fn is_call(value: &Value, id: &str, numbers: &[f64]) -> bool {
 fn is_number(value: &Value, expected: f64) -> bool {
     matches!(value, Value::Number(actual) if *actual == expected)
 }
+
+#[test]
+fn mapped_text_is_constructible_outside_the_crate() {
+    let catalog = Catalog::builtin().expect("built-in catalog");
+    let locale = Locale::new("en-US");
+    let program = parser::parse(
+        r#"rule ("mapped") {
+        event { Ongoing - Global; }
+        actions { Wait(1, Ignore Condition); }
+    }"#,
+        &catalog,
+        &locale,
+    )
+    .expect("Workshop parses");
+    let text = emitter::emit(&program, &catalog, &locale).expect("canonical emission");
+
+    let artifact = MappedText::new(text.clone(), SourceMap::extract(&program));
+    assert_eq!(artifact.text, text);
+    let decoded = MappedText::from_json(&artifact.to_json()).expect("artifact decodes");
+    assert_eq!(decoded, artifact);
+}
diff --git a/docs/README.md b/docs/README.md
index eeb3d8f..62ad11a 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -30,7 +30,8 @@ relevant code/tests/data and current Issue contract.
   shared implementation boundaries, CLI verification tooling, and test-owned
   fixtures.
 - [Public API and compatibility contract](compatibility-facades.md): crate-root
-  module exports, root re-exports, and retired compatibility paths.
+  module exports, root re-exports, retired compatibility paths, and which
+  public types may grow without a breaking change.
 - [Repository agent guidance](../AGENTS.md): implementation routing,
   verification, source attribution, and delivery rules.
 
diff --git a/docs/compatibility-facades.md b/docs/compatibility-facades.md
index feb032d..236ab9d 100644
--- a/docs/compatibility-facades.md
+++ b/docs/compatibility-facades.md
@@ -63,3 +63,20 @@ public Rust item private or remove its compatibility consequences. Before 1.0,
 implementation-only public exports may be removed as intentional breaking
 changes. Consumer migrations are owned by their respective repositories and do
 not need to precede an owner-side breaking release.
+
+## Growth without breaking changes
+
+Public types expected to grow in 1.x are `#[non_exhaustive]`: error enums and
+error records, options, operation outputs and reports, catalog and gameplay
+identity/metadata records, settings source metadata, and the settings scope and
+value-domain enums. `Rule`, `Condition`, `PlayerEventKind`, and `ModifyOp` are
+also `#[non_exhaustive]`. Consumers match them with a wildcard arm and read
+their fields, but do not build them with struct literals. Options are built
+from `Default` and then assigned field by field; records that consumers need to
+build, such as `MappedText`, `gameplay::SourceReference`, and
+`gameplay::GameplayDatasetIdentity`, have a `new` constructor.
+
+The canonical program model (`Action`, `Value`, `Event`, `EventTeam`,
+`EventTarget`), `catalog::Kind`, source positions and spans, and values that
+consumers construct stay exhaustive. New Workshop content reaches them through
+catalog ids and `Call`, not new variants.