Declare each provider's defaults once, in plugin.toml

plugins/summarize/plugin.toml

@@ -12,15 +12,19 @@ default = false
 
 [options.provider]
 enum = ["gemini", "openai", "anthropic"]
+"x-enum-titles" = ["Gemini", "OpenAI", "Anthropic"]
 title = "Provider"
-description = "Which model API to call. `openai` also reaches OpenRouter and any other OpenAI-compatible server through `endpoint`. Set `model` to one of the provider's models when you change this."
+description = "Which model API to call. `openai` also reaches OpenRouter and any other OpenAI-compatible server through `endpoint`."
 default = "gemini"
 
 [options.model]
 type = "string"
 title = "Model"
-description = "The model name sent to the provider."
-default = "gemini-3.8-flash"
+description = "The model name sent to the provider. Unset uses the provider's default."
+
+[options.model."x-default-by"]
+key = "provider"
+values = { gemini = "gemini-3.8-flash", openai = "gpt-6-luna", anthropic = "claude-haiku-4-5" }
 
 [options.min_lines]
 type = "integer"
@@ -64,7 +68,7 @@ default = 3
 [options.system_prompt]
 type = "string"
 title = "System prompt"
-description = "The system instruction sent with every request; diffr builds each request's message from the file's numbered lines and the folds to summarize. Unset uses the default: https://github.com/devdotfast/diffr/blob/main/plugins/summarize/plugin.toml#L68-L74"
+description = "The system instruction sent with every request; diffr builds each request's message from the file's numbered lines and the folds to summarize. Unset uses the default: https://github.com/devdotfast/diffr/blob/main/plugins/summarize/plugin.toml#L72-L78"
 default = """\
 For each listed fold, rewrite that function body as short \
 pseudocode. Keep the names. No prose, no comments, no code fences. Use as few lines as \
@@ -85,3 +89,35 @@ minimum = 0
 title = "Shortest test body to summarize (lines)"
 description = "Test bodies shorter than this keep their ordinary fold labels."
 default = 20
+
+# Per-provider facts the summarizer and settings screens share. Settings
+# screens do not edit an object option, so this is a file-only override.
+[options.provider_details]
+type = "object"
+title = "Provider details"
+description = "The provider's default endpoint, the environment variables that hold its key, and whether a custom endpoint may go without a key."
+required = ["endpoint", "key_variables", "keyless_custom_endpoint"]
+additionalProperties = false
+
+[options.provider_details.properties]
+endpoint = { type = "string" }
+key_variables = { type = "array", items = { type = "string" } }
+keyless_custom_endpoint = { type = "boolean" }
+
+[options.provider_details."x-default-by"]
+key = "provider"
+
+[options.provider_details."x-default-by".values.gemini]
+endpoint = "https://generativelanguage.googleapis.com"
+key_variables = ["GEMINI_API_KEY", "GOOGLE_API_KEY"]
+keyless_custom_endpoint = false
+
+[options.provider_details."x-default-by".values.openai]
+endpoint = "https://api.openai.com/v1"
+key_variables = ["OPENAI_API_KEY"]
+keyless_custom_endpoint = true
+
+[options.provider_details."x-default-by".values.anthropic]
+endpoint = "https://api.anthropic.com"
+key_variables = ["ANTHROPIC_API_KEY"]
+keyless_custom_endpoint = false

plugins/summarize/src/lib.rs

@@ -15,7 +15,7 @@ use std::collections::BTreeMap;
 use std::time::Duration;
 mod http;
 mod provider;
-pub use provider::Provider;
+pub use provider::{Details, Provider};
 
 /// The plugin's name, and the tags its queries set: a function body, and a
 /// test body, which can be summarized independently of whether it is new.
@@ -28,6 +28,7 @@ const TEST: &str = "summarize:test";
 #[serde(deny_unknown_fields)]
 pub struct Options {
     pub provider: Provider,
+    pub provider_details: Details,
     pub model: String,
     pub min_lines: usize,
     pub tests: bool,
@@ -305,7 +306,7 @@ fn resolve_key(config: &Options, custom_endpoint: bool) -> anyhow::Result<Option
     if let Some(key) = config.api_key.clone().filter(set) {
         return Ok(Some(key));
     }
-    let variables = config.provider.key_variables();
+    let variables = &config.provider_details.key_variables;
     for variable in variables {
         if let Some(key) = std::env::var_os(variable) {
             let key = key
@@ -316,7 +317,7 @@ fn resolve_key(config: &Options, custom_endpoint: bool) -> anyhow::Result<Option
             }
         }
     }
-    if config.provider.key_optional(custom_endpoint) {
+    if config.provider_details.keyless_custom_endpoint && custom_endpoint {
         return Ok(None);
     }
     anyhow::bail!(
@@ -336,7 +337,7 @@ impl Plugin for Summarize {
         let api_key = resolve_key(&options, endpoint.is_some())?;
         Ok(Self {
             api_key,
-            endpoint: endpoint.unwrap_or_else(|| options.provider.default_endpoint().to_owned()),
+            endpoint: endpoint.unwrap_or_else(|| options.provider_details.endpoint.clone()),
             options,
         })
     }

plugins/summarize/src/provider.rs

@@ -4,6 +4,19 @@ use serde::de::DeserializeOwned;
 use serde::Deserialize;
 use serde_json::{json, Value};
 
+/// What `plugin.toml` records per provider, filled in by the host.
+#[derive(Clone, Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct Details {
+    /// The base URL used when `endpoint` is unset.
+    pub endpoint: String,
+    /// The environment variables read, in order, when `api_key` is unset.
+    pub key_variables: Vec<String>,
+    /// Whether a custom endpoint may go without a key, as OpenAI-compatible
+    /// servers such as Ollama often do.
+    pub keyless_custom_endpoint: bool,
+}
+
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Deserialize)]
 #[serde(rename_all = "lowercase")]
 pub enum Provider {
@@ -13,29 +26,6 @@ pub enum Provider {
 }
 
 impl Provider {
-    pub fn default_endpoint(self) -> &'static str {
-        match self {
-            Self::Gemini => "https://generativelanguage.googleapis.com",
-            Self::OpenAi => "https://api.openai.com/v1",
-            Self::Anthropic => "https://api.anthropic.com",
-        }
-    }
-
-    /// The environment variables read, in order, when `api_key` is unset.
-    pub fn key_variables(self) -> &'static [&'static str] {
-        match self {
-            Self::Gemini => &["GEMINI_API_KEY", "GOOGLE_API_KEY"],
-            Self::OpenAi => &["OPENAI_API_KEY"],
-            Self::Anthropic => &["ANTHROPIC_API_KEY"],
-        }
-    }
-
-    /// OpenAI-compatible servers at a custom endpoint, such as Ollama,
-    /// often take no key.
-    pub fn key_optional(self, custom_endpoint: bool) -> bool {
-        self == Self::OpenAi && custom_endpoint
-    }
-
     pub fn url(self, endpoint: &str, model: &str) -> String {
         let endpoint = endpoint.trim_end_matches('/');
         match self {

src/config/default.toml

@@ -39,7 +39,6 @@ min_lines = 5
 [plugins.bundled.summarize]
 enabled = false
 provider = "gemini"
-model = "gemini-3.8-flash"
 min_lines = 20
 tests = true
 test_min_lines = 20

src/config/prune.rs

@@ -38,15 +38,15 @@ pub(crate) fn forget_legacy(source: &str) -> Cow<'_, str> {
     }
 }
 
-/// Remove each value, then each table that holds no values, whose removal
-/// leaves `resolve` of the document unchanged. `version` stays, and so does
+/// Remove each value, then each table, whose removal leaves `resolve` of
+/// the document unchanged: an object option is only valid whole. `version` stays, and so does
 /// anything with a comment on it: a note marks intent.
 pub(crate) fn prune(document: &mut DocumentMut, resolve: impl Fn(&str) -> Option<toml::Value>) {
     let Some(target) = resolve(&document.to_string()) else {
         return;
     };
-    for hollow_tables in [false, true] {
-        for path in removable(document.as_table(), hollow_tables) {
+    for tables in [false, true] {
+        for path in removable(document.as_table(), tables) {
             if path == ["version"] {
                 continue;
             }
@@ -75,34 +75,36 @@ fn hide_headers(table: &mut toml_edit::Table) {
     }
 }
 
-/// The dotted paths of the table's uncommented values or, with
-/// `hollow_tables`, of its outermost tables that hold no values, deepest
-/// first.
-fn removable(table: &dyn TableLike, hollow_tables: bool) -> Vec<Vec<String>> {
+/// The dotted paths of the table's uncommented values or, with `tables`,
+/// of its uncommented tables, deepest first. A table holding a comment at
+/// any depth stays.
+fn removable(table: &dyn TableLike, tables: bool) -> Vec<Vec<String>> {
     let mut paths = Vec::new();
     for (key, item) in table.iter() {
         if has_comment(table, key, item) {
             continue;
         }
         match item.as_table_like() {
-            Some(child) if hollow_tables && hollow(child) => paths.push(vec![key.to_owned()]),
             Some(child) => {
-                for mut path in removable(child, hollow_tables) {
+                for mut path in removable(child, tables) {
                     path.insert(0, key.to_owned());
                     paths.push(path);
                 }
+                if tables && !annotated(child) {
+                    paths.push(vec![key.to_owned()]);
+                }
             }
-            None if !hollow_tables => paths.push(vec![key.to_owned()]),
+            None if !tables => paths.push(vec![key.to_owned()]),
             None => {}
         }
     }
     paths
 }
 
-/// A table with no values and no comments, at any depth.
-fn hollow(table: &dyn TableLike) -> bool {
-    table.iter().all(|(key, item)| {
-        !has_comment(table, key, item) && item.as_table_like().is_some_and(hollow)
+/// Whether anything in the table, at any depth, has a comment.
+fn annotated(table: &dyn TableLike) -> bool {
+    table.iter().any(|(key, item)| {
+        has_comment(table, key, item) || item.as_table_like().is_some_and(annotated)
     })
 }
 

src/config/prune/tests.rs

@@ -17,6 +17,8 @@ fn settings() -> Vec<(String, Value)> {
             None => node,
         };
         match node.get("properties").and_then(Value::as_object) {
+            // An object option is set whole, from the file, never by field.
+            Some(_) if node.get("x-settings") == Some(&Value::Bool(false)) => {}
             Some(properties) => {
                 for (name, child) in properties {
                     let key = match key {

src/config/store.rs

@@ -588,6 +588,27 @@ mod sparse_tests {
         assert!(!text.contains("plugins"), "{text}");
     }
 
+    #[test]
+    fn a_model_equal_to_its_providers_default_is_dropped() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("config.toml");
+        set(&path, "plugins.bundled.summarize.provider", "openai").unwrap();
+        set(&path, "plugins.bundled.summarize.model", "gpt-6-luna").unwrap();
+        let raw = read_toml(&path);
+        assert!(
+            raw["plugins"]["bundled"]["summarize"]
+                .get("model")
+                .is_none(),
+            "{raw}"
+        );
+        set(&path, "plugins.bundled.summarize.model", "gemini-3.8-flash").unwrap();
+        let raw = read_toml(&path);
+        assert_eq!(
+            raw["plugins"]["bundled"]["summarize"]["model"].as_str(),
+            Some("gemini-3.8-flash")
+        );
+    }
+
     #[test]
     fn an_explicit_plugin_list_still_pins_membership() {
         let dir = tempfile::tempdir().unwrap();