graphql,graph: Add GraphQL schema and resolver for _logs query

Adds GraphQL API for querying subgraph logs:

Schema types:
- LogLevel enum (CRITICAL, ERROR, WARNING, INFO, DEBUG)
- _Log_ type with id, timestamp, level, text, arguments, meta
- _LogArgument_ type for structured key-value pairs
- _LogMeta_ type for source location (module, line, column)

Query field (_logs) with filters:
- level: Filter by log level
- from/to: Timestamp range (ISO 8601)
- search: Text search in log messages
- first/skip: Pagination (max 1000, skip max 10000)

Author: fordN

graph/src/schema/api.rs

@@ -10,7 +10,7 @@ use crate::cheap_clone::CheapClone;
 use crate::data::graphql::{ObjectOrInterface, ObjectTypeExt, TypeExt};
 use crate::data::store::IdType;
 use crate::env::ENV_VARS;
-use crate::schema::{ast, META_FIELD_NAME, META_FIELD_TYPE, SCHEMA_TYPE_NAME};
+use crate::schema::{ast, LOGS_FIELD_NAME, META_FIELD_NAME, META_FIELD_TYPE, SCHEMA_TYPE_NAME};
 
 use crate::data::graphql::ext::{
     camel_cased_names, DefinitionExt, DirectiveExt, DocumentExt, ValueExt,
@@ -349,7 +349,7 @@ pub(in crate::schema) fn api_schema(
 ) -> Result<s::Document, APISchemaError> {
     // Refactor: Don't clone the schema.
     let mut api = init_api_schema(input_schema)?;
-    add_meta_field_type(&mut api.document);
+    add_builtin_field_types(&mut api.document);
     add_types_for_object_types(&mut api, input_schema)?;
     add_types_for_interface_types(&mut api, input_schema)?;
     add_types_for_aggregation_types(&mut api, input_schema)?;
@@ -444,18 +444,24 @@ fn init_api_schema(input_schema: &InputSchema) -> Result<Schema, APISchemaError>
         .map_err(|e| APISchemaError::SchemaCreationFailed(e.to_string()))
 }
 
-/// Adds a global `_Meta_` type to the schema. The `_meta` field
-/// accepts values of this type
-fn add_meta_field_type(api: &mut s::Document) {
+/// Adds built-in field types to the schema. Currently adds `_Meta_` and `_Log_` types
+/// which are used by the `_meta` and `_logs` fields respectively.
+fn add_builtin_field_types(api: &mut s::Document) {
     lazy_static! {
         static ref META_FIELD_SCHEMA: s::Document = {
             let schema = include_str!("meta.graphql");
             s::parse_schema(schema).expect("the schema `meta.graphql` is invalid")
         };
+        static ref LOGS_FIELD_SCHEMA: s::Document = {
+            let schema = include_str!("logs.graphql");
+            s::parse_schema(schema).expect("the schema `logs.graphql` is invalid")
+        };
     }
 
     api.definitions
         .extend(META_FIELD_SCHEMA.definitions.iter().cloned());
+    api.definitions
+        .extend(LOGS_FIELD_SCHEMA.definitions.iter().cloned());
 }
 
 fn add_types_for_object_types(
@@ -1098,6 +1104,7 @@ fn add_query_type(api: &mut s::Document, input_schema: &InputSchema) -> Result<(
     fields.append(&mut agg_fields);
     fields.append(&mut fulltext_fields);
     fields.push(meta_field());
+    fields.push(logs_field());
 
     let typedef = s::TypeDefinition::Object(s::ObjectType {
         position: q::Pos::default(),
@@ -1303,6 +1310,102 @@ fn meta_field() -> s::Field {
     META_FIELD.clone()
 }
 
+fn logs_field() -> s::Field {
+    lazy_static! {
+        static ref LOGS_FIELD: s::Field = s::Field {
+            position: Pos::default(),
+            description: Some(
+                "Query execution logs emitted by the subgraph during indexing. \
+                Results are sorted by timestamp in descending order (newest first)."
+                .to_string()
+            ),
+            name: LOGS_FIELD_NAME.to_string(),
+            arguments: vec![
+                // level: LogLevel
+                s::InputValue {
+                    position: Pos::default(),
+                    description: Some(
+                        "Filter logs by severity level. Only logs at this level will be returned."
+                        .to_string()
+                    ),
+                    name: String::from("level"),
+                    value_type: s::Type::NamedType(String::from("LogLevel")),
+                    default_value: None,
+                    directives: vec![],
+                },
+                // from: String (RFC3339 timestamp)
+                s::InputValue {
+                    position: Pos::default(),
+                    description: Some(
+                        "Filter logs from this timestamp onwards (inclusive). \
+                        Must be in RFC3339 format (e.g., '2024-01-15T10:30:00Z')."
+                        .to_string()
+                    ),
+                    name: String::from("from"),
+                    value_type: s::Type::NamedType(String::from("String")),
+                    default_value: None,
+                    directives: vec![],
+                },
+                // to: String (RFC3339 timestamp)
+                s::InputValue {
+                    position: Pos::default(),
+                    description: Some(
+                        "Filter logs until this timestamp (inclusive). \
+                        Must be in RFC3339 format (e.g., '2024-01-15T23:59:59Z')."
+                        .to_string()
+                    ),
+                    name: String::from("to"),
+                    value_type: s::Type::NamedType(String::from("String")),
+                    default_value: None,
+                    directives: vec![],
+                },
+                // search: String (full-text search)
+                s::InputValue {
+                    position: Pos::default(),
+                    description: Some(
+                        "Search for logs containing this text in the message. \
+                        Case-insensitive substring match. Maximum length: 1000 characters."
+                        .to_string()
+                    ),
+                    name: String::from("search"),
+                    value_type: s::Type::NamedType(String::from("String")),
+                    default_value: None,
+                    directives: vec![],
+                },
+                // first: Int (default 100, max 1000)
+                s::InputValue {
+                    position: Pos::default(),
+                    description: Some(
+                        "Maximum number of logs to return. Default: 100, Maximum: 1000."
+                        .to_string()
+                    ),
+                    name: String::from("first"),
+                    value_type: s::Type::NamedType(String::from("Int")),
+                    default_value: Some(s::Value::Int(100.into())),
+                    directives: vec![],
+                },
+                // skip: Int (default 0, max 10000)
+                s::InputValue {
+                    position: Pos::default(),
+                    description: Some(
+                        "Number of logs to skip (for pagination). Default: 0, Maximum: 10000."
+                        .to_string()
+                    ),
+                    name: String::from("skip"),
+                    value_type: s::Type::NamedType(String::from("Int")),
+                    default_value: Some(s::Value::Int(0.into())),
+                    directives: vec![],
+                },
+            ],
+            field_type: s::Type::NonNullType(Box::new(s::Type::ListType(Box::new(
+                s::Type::NonNullType(Box::new(s::Type::NamedType(String::from("_Log_")))),
+            )))),
+            directives: vec![],
+        };
+    }
+    LOGS_FIELD.clone()
+}
+
 #[cfg(test)]
 mod tests {
     use crate::{

graph/src/schema/logs.graphql

@@ -0,0 +1,61 @@
+"""
+The severity level of a log entry.
+Log levels are ordered from most to least severe: CRITICAL > ERROR > WARNING > INFO > DEBUG
+"""
+enum LogLevel {
+  "Critical errors that require immediate attention"
+  CRITICAL
+  "Error conditions that indicate a failure"
+  ERROR
+  "Warning conditions that may require attention"
+  WARNING
+  "Informational messages about normal operations"
+  INFO
+  "Detailed diagnostic information for debugging"
+  DEBUG
+}
+
+"""
+A log entry emitted by a subgraph during indexing.
+Logs can be generated by the subgraph's AssemblyScript code using the `log.*` functions.
+"""
+type _Log_ {
+  "Unique identifier for this log entry"
+  id: String!
+  "The deployment hash of the subgraph that emitted this log"
+  subgraphId: String!
+  "The timestamp when the log was emitted, in RFC3339 format (e.g., '2024-01-15T10:30:00Z')"
+  timestamp: String!
+  "The severity level of the log entry"
+  level: LogLevel!
+  "The log message text"
+  text: String!
+  "Additional structured data passed to the log function as key-value pairs"
+  arguments: [_LogArgument_!]!
+  "Metadata about the source location in the subgraph code where the log was emitted"
+  meta: _LogMeta_!
+}
+
+"""
+A key-value pair of additional data associated with a log entry.
+These correspond to arguments passed to the log function in the subgraph code.
+"""
+type _LogArgument_ {
+  "The parameter name"
+  key: String!
+  "The parameter value, serialized as a string"
+  value: String!
+}
+
+"""
+Source code location metadata for a log entry.
+Indicates where in the subgraph's AssemblyScript code the log statement was executed.
+"""
+type _LogMeta_ {
+  "The module or file path where the log was emitted"
+  module: String!
+  "The line number in the source file"
+  line: Int!
+  "The column number in the source file"
+  column: Int!
+}

graph/src/schema/mod.rs

@@ -41,6 +41,9 @@ pub const INTROSPECTION_SCHEMA_FIELD_NAME: &str = "__schema";
 pub const META_FIELD_TYPE: &str = "_Meta_";
 pub const META_FIELD_NAME: &str = "_meta";
 
+pub const LOGS_FIELD_TYPE: &str = "_Log_";
+pub const LOGS_FIELD_NAME: &str = "_logs";
+
 pub const INTROSPECTION_TYPE_FIELD_NAME: &str = "__type";
 
 pub const BLOCK_FIELD_TYPE: &str = "_Block_";