diff --git a/packages/core/src/api/api/resources/commons/types/BaseScore.ts b/packages/core/src/api/api/resources/commons/types/BaseScore.ts
index d560c1c7..564c9305 100644
--- a/packages/core/src/api/api/resources/commons/types/BaseScore.ts
+++ b/packages/core/src/api/api/resources/commons/types/BaseScore.ts
@@ -6,22 +6,29 @@ import * as LangfuseAPI from "../../../index.js";
 
 export interface BaseScore {
   id: string;
-  traceId?: string;
-  sessionId?: string;
-  observationId?: string;
-  datasetRunId?: string;
+  /** The trace ID associated with the score */
+  traceId?: string | null;
+  /** The session ID associated with the score */
+  sessionId?: string | null;
+  /** The observation ID associated with the score */
+  observationId?: string | null;
+  /** The dataset run ID associated with the score */
+  datasetRunId?: string | null;
   name: string;
   source: LangfuseAPI.ScoreSource;
   timestamp: string;
   createdAt: string;
   updatedAt: string;
-  authorUserId?: string;
-  comment?: string;
+  /** The user ID of the author */
+  authorUserId: string | null;
+  /** Comment on the score */
+  comment: string | null;
+  /** Metadata associated with the score */
   metadata?: unknown;
   /** Reference a score config on a score. When set, config and score name must be equal and value must comply to optionally defined numerical range */
-  configId?: string;
+  configId: string | null;
   /** The annotation queue referenced by the score. Indicates if score was initially created while processing annotation queue. */
-  queueId?: string;
+  queueId: string | null;
   /** The environment from which this score originated. Can be any lowercase alphanumeric string with hyphens and underscores that does not start with 'langfuse'. */
-  environment?: string;
+  environment: string;
 }
diff --git a/packages/core/src/api/api/resources/commons/types/BaseScoreV1.ts b/packages/core/src/api/api/resources/commons/types/BaseScoreV1.ts
index 296be6eb..93eafaaa 100644
--- a/packages/core/src/api/api/resources/commons/types/BaseScoreV1.ts
+++ b/packages/core/src/api/api/resources/commons/types/BaseScoreV1.ts
@@ -9,17 +9,21 @@ export interface BaseScoreV1 {
   traceId: string;
   name: string;
   source: LangfuseAPI.ScoreSource;
-  observationId?: string;
+  /** The observation ID associated with the score */
+  observationId?: string | null;
   timestamp: string;
   createdAt: string;
   updatedAt: string;
-  authorUserId?: string;
-  comment?: string;
+  /** The user ID of the author */
+  authorUserId: string | null;
+  /** Comment on the score */
+  comment: string | null;
+  /** Metadata associated with the score */
   metadata?: unknown;
   /** Reference a score config on a score. When set, config and score name must be equal and value must comply to optionally defined numerical range */
-  configId?: string;
+  configId: string | null;
   /** The annotation queue referenced by the score. Indicates if score was initially created while processing annotation queue. */
-  queueId?: string;
+  queueId: string | null;
   /** The environment from which this score originated. Can be any lowercase alphanumeric string with hyphens and underscores that does not start with 'langfuse'. */
-  environment?: string;
+  environment: string;
 }
diff --git a/packages/core/src/api/api/resources/commons/types/Comment.ts b/packages/core/src/api/api/resources/commons/types/Comment.ts
index b7343df8..1da333a6 100644
--- a/packages/core/src/api/api/resources/commons/types/Comment.ts
+++ b/packages/core/src/api/api/resources/commons/types/Comment.ts
@@ -12,5 +12,6 @@ export interface Comment {
   objectType: LangfuseAPI.CommentObjectType;
   objectId: string;
   content: string;
-  authorUserId?: string;
+  /** The user ID of the comment author */
+  authorUserId?: string | null;
 }
diff --git a/packages/core/src/api/api/resources/commons/types/Dataset.ts b/packages/core/src/api/api/resources/commons/types/Dataset.ts
index 6252a563..10e5102a 100644
--- a/packages/core/src/api/api/resources/commons/types/Dataset.ts
+++ b/packages/core/src/api/api/resources/commons/types/Dataset.ts
@@ -5,12 +5,14 @@
 export interface Dataset {
   id: string;
   name: string;
-  description?: string;
+  /** Description of the dataset */
+  description: string | null;
+  /** Metadata associated with the dataset */
   metadata?: unknown;
   /** JSON Schema for validating dataset item inputs */
-  inputSchema?: unknown;
+  inputSchema: unknown | null;
   /** JSON Schema for validating dataset item expected outputs */
-  expectedOutputSchema?: unknown;
+  expectedOutputSchema: unknown | null;
   projectId: string;
   createdAt: string;
   updatedAt: string;
diff --git a/packages/core/src/api/api/resources/commons/types/DatasetItem.ts b/packages/core/src/api/api/resources/commons/types/DatasetItem.ts
index b1b883b7..86af473e 100644
--- a/packages/core/src/api/api/resources/commons/types/DatasetItem.ts
+++ b/packages/core/src/api/api/resources/commons/types/DatasetItem.ts
@@ -7,11 +7,16 @@ import * as LangfuseAPI from "../../../index.js";
 export interface DatasetItem {
   id: string;
   status: LangfuseAPI.DatasetStatus;
+  /** Input data for the dataset item */
   input?: unknown;
+  /** Expected output for the dataset item */
   expectedOutput?: unknown;
+  /** Metadata associated with the dataset item */
   metadata?: unknown;
-  sourceTraceId?: string;
-  sourceObservationId?: string;
+  /** The trace ID that sourced this dataset item */
+  sourceTraceId: string | null;
+  /** The observation ID that sourced this dataset item */
+  sourceObservationId: string | null;
   datasetId: string;
   datasetName: string;
   createdAt: string;
diff --git a/packages/core/src/api/api/resources/commons/types/DatasetRun.ts b/packages/core/src/api/api/resources/commons/types/DatasetRun.ts
index fadbb31f..27fca139 100644
--- a/packages/core/src/api/api/resources/commons/types/DatasetRun.ts
+++ b/packages/core/src/api/api/resources/commons/types/DatasetRun.ts
@@ -8,7 +8,7 @@ export interface DatasetRun {
   /** Name of the dataset run */
   name: string;
   /** Description of the run */
-  description?: string;
+  description: string | null;
   /** Metadata of the dataset run */
   metadata?: unknown;
   /** Id of the associated dataset */
diff --git a/packages/core/src/api/api/resources/commons/types/DatasetRunItem.ts b/packages/core/src/api/api/resources/commons/types/DatasetRunItem.ts
index 3306977d..da44a2bc 100644
--- a/packages/core/src/api/api/resources/commons/types/DatasetRunItem.ts
+++ b/packages/core/src/api/api/resources/commons/types/DatasetRunItem.ts
@@ -8,7 +8,8 @@ export interface DatasetRunItem {
   datasetRunName: string;
   datasetItemId: string;
   traceId: string;
-  observationId?: string;
+  /** The observation ID associated with this run item */
+  observationId: string | null;
   createdAt: string;
   updatedAt: string;
 }
diff --git a/packages/core/src/api/api/resources/commons/types/Model.ts b/packages/core/src/api/api/resources/commons/types/Model.ts
index 7aebbf76..4e06d9ec 100644
--- a/packages/core/src/api/api/resources/commons/types/Model.ts
+++ b/packages/core/src/api/api/resources/commons/types/Model.ts
@@ -22,17 +22,17 @@ export interface Model {
   /** Regex pattern which matches this model definition to generation.model. Useful in case of fine-tuned models. If you want to exact match, use `(?i)^modelname$` */
   matchPattern: string;
   /** Apply only to generations which are newer than this ISO date. */
-  startDate?: string;
+  startDate: string | null;
   /** Unit used by this model. */
-  unit?: LangfuseAPI.ModelUsageUnit;
+  unit?: LangfuseAPI.ModelUsageUnit | null;
   /** Deprecated. See 'prices' instead. Price (USD) per input unit */
-  inputPrice?: number;
+  inputPrice: number | null;
   /** Deprecated. See 'prices' instead. Price (USD) per output unit */
-  outputPrice?: number;
+  outputPrice: number | null;
   /** Deprecated. See 'prices' instead. Price (USD) per total unit. Cannot be set if input or output price is set. */
-  totalPrice?: number;
+  totalPrice: number | null;
   /** Optional. Tokenizer to be applied to observations which match to this model. See docs for more details. */
-  tokenizerId?: string;
+  tokenizerId: string | null;
   /** Optional. Configuration for the selected tokenizer. Needs to be JSON. See docs for more details. */
   tokenizerConfig?: unknown;
   isLangfuseManaged: boolean;
diff --git a/packages/core/src/api/api/resources/commons/types/Observation.ts b/packages/core/src/api/api/resources/commons/types/Observation.ts
index 19a2210b..61d99179 100644
--- a/packages/core/src/api/api/resources/commons/types/Observation.ts
+++ b/packages/core/src/api/api/resources/commons/types/Observation.ts
@@ -8,43 +8,43 @@ export interface Observation {
   /** The unique identifier of the observation */
   id: string;
   /** The trace ID associated with the observation */
-  traceId?: string;
+  traceId: string | null;
   /** The type of the observation */
   type: string;
   /** The name of the observation */
-  name?: string;
+  name: string | null;
   /** The start time of the observation */
   startTime: string;
   /** The end time of the observation. */
-  endTime?: string;
+  endTime: string | null;
   /** The completion start time of the observation */
-  completionStartTime?: string;
+  completionStartTime: string | null;
   /** The model used for the observation */
-  model?: string;
+  model: string | null;
   /** The parameters of the model used for the observation */
-  modelParameters?: Record<string, LangfuseAPI.MapValue>;
+  modelParameters?: unknown;
   /** The input data of the observation */
   input?: unknown;
   /** The version of the observation */
-  version?: string;
+  version: string | null;
   /** Additional metadata of the observation */
   metadata?: unknown;
   /** The output data of the observation */
   output?: unknown;
   /** (Deprecated. Use usageDetails and costDetails instead.) The usage data of the observation */
-  usage?: LangfuseAPI.Usage;
+  usage: LangfuseAPI.Usage;
   /** The level of the observation */
   level: LangfuseAPI.ObservationLevel;
   /** The status message of the observation */
-  statusMessage?: string;
+  statusMessage: string | null;
   /** The parent observation ID */
-  parentObservationId?: string;
+  parentObservationId: string | null;
   /** The prompt ID associated with the observation */
-  promptId?: string;
+  promptId: string | null;
   /** The usage details of the observation. Key is the name of the usage metric, value is the number of units consumed. The total key is the sum of all (non-total) usage metrics or the total value ingested. */
-  usageDetails?: Record<string, number>;
+  usageDetails: Record<string, number>;
   /** The cost details of the observation. Key is the name of the cost metric, value is the cost in USD. The total key is the sum of all (non-total) cost metrics or the total value ingested. */
-  costDetails?: Record<string, number>;
+  costDetails: Record<string, number>;
   /** The environment from which this observation originated. Can be any lowercase alphanumeric string with hyphens and underscores that does not start with 'langfuse'. */
-  environment?: string;
+  environment: string;
 }
diff --git a/packages/core/src/api/api/resources/commons/types/ObservationsView.ts b/packages/core/src/api/api/resources/commons/types/ObservationsView.ts
index 2d4dff5b..37fd77c8 100644
--- a/packages/core/src/api/api/resources/commons/types/ObservationsView.ts
+++ b/packages/core/src/api/api/resources/commons/types/ObservationsView.ts
@@ -6,25 +6,25 @@ import * as LangfuseAPI from "../../../index.js";
 
 export interface ObservationsView extends LangfuseAPI.Observation {
   /** The name of the prompt associated with the observation */
-  promptName?: string;
+  promptName: string | null;
   /** The version of the prompt associated with the observation */
-  promptVersion?: number;
+  promptVersion: number | null;
   /** The unique identifier of the model */
-  modelId?: string;
+  modelId: string | null;
   /** The price of the input in USD */
-  inputPrice?: number;
+  inputPrice: number | null;
   /** The price of the output in USD. */
-  outputPrice?: number;
+  outputPrice: number | null;
   /** The total price in USD. */
-  totalPrice?: number;
+  totalPrice: number | null;
   /** (Deprecated. Use usageDetails and costDetails instead.) The calculated cost of the input in USD */
-  calculatedInputCost?: number;
+  calculatedInputCost: number | null;
   /** (Deprecated. Use usageDetails and costDetails instead.) The calculated cost of the output in USD */
-  calculatedOutputCost?: number;
+  calculatedOutputCost: number | null;
   /** (Deprecated. Use usageDetails and costDetails instead.) The calculated total cost in USD */
-  calculatedTotalCost?: number;
+  calculatedTotalCost: number | null;
   /** The latency in seconds. */
-  latency?: number;
+  latency: number | null;
   /** The time to the first token in seconds */
-  timeToFirstToken?: number;
+  timeToFirstToken: number | null;
 }
diff --git a/packages/core/src/api/api/resources/commons/types/ScoreConfig.ts b/packages/core/src/api/api/resources/commons/types/ScoreConfig.ts
index bfd8cff6..cbe23ed7 100644
--- a/packages/core/src/api/api/resources/commons/types/ScoreConfig.ts
+++ b/packages/core/src/api/api/resources/commons/types/ScoreConfig.ts
@@ -17,10 +17,11 @@ export interface ScoreConfig {
   /** Whether the score config is archived. Defaults to false */
   isArchived: boolean;
   /** Sets minimum value for numerical scores. If not set, the minimum value defaults to -∞ */
-  minValue?: number;
+  minValue?: number | null;
   /** Sets maximum value for numerical scores. If not set, the maximum value defaults to +∞ */
-  maxValue?: number;
+  maxValue?: number | null;
   /** Configures custom categories for categorical scores */
   categories?: LangfuseAPI.ConfigCategory[];
-  description?: string;
+  /** Description of the score config */
+  description?: string | null;
 }
diff --git a/packages/core/src/api/api/resources/commons/types/Session.ts b/packages/core/src/api/api/resources/commons/types/Session.ts
index 9c326bf3..24c83224 100644
--- a/packages/core/src/api/api/resources/commons/types/Session.ts
+++ b/packages/core/src/api/api/resources/commons/types/Session.ts
@@ -7,5 +7,5 @@ export interface Session {
   createdAt: string;
   projectId: string;
   /** The environment from which this session originated. */
-  environment?: string;
+  environment: string;
 }
diff --git a/packages/core/src/api/api/resources/commons/types/Trace.ts b/packages/core/src/api/api/resources/commons/types/Trace.ts
index e16dd811..83cc99ae 100644
--- a/packages/core/src/api/api/resources/commons/types/Trace.ts
+++ b/packages/core/src/api/api/resources/commons/types/Trace.ts
@@ -8,25 +8,25 @@ export interface Trace {
   /** The timestamp when the trace was created */
   timestamp: string;
   /** The name of the trace */
-  name?: string;
+  name: string | null;
   /** The input data of the trace. Can be any JSON. */
   input?: unknown;
   /** The output data of the trace. Can be any JSON. */
   output?: unknown;
   /** The session identifier associated with the trace */
-  sessionId?: string;
+  sessionId: string | null;
   /** The release version of the application when the trace was created */
-  release?: string;
+  release: string | null;
   /** The version of the trace */
-  version?: string;
+  version: string | null;
   /** The user identifier associated with the trace */
-  userId?: string;
+  userId: string | null;
   /** The metadata associated with the trace. Can be any JSON. */
   metadata?: unknown;
-  /** The tags associated with the trace. Can be an array of strings or null. */
-  tags?: string[];
+  /** The tags associated with the trace. */
+  tags: string[];
   /** Public traces are accessible via url without login */
-  public?: boolean;
+  public: boolean;
   /** The environment from which this trace originated. Can be any lowercase alphanumeric string with hyphens and underscores that does not start with 'langfuse'. */
-  environment?: string;
+  environment: string;
 }
diff --git a/packages/core/src/api/api/resources/commons/types/TraceWithDetails.ts b/packages/core/src/api/api/resources/commons/types/TraceWithDetails.ts
index f95e12c2..d11a534b 100644
--- a/packages/core/src/api/api/resources/commons/types/TraceWithDetails.ts
+++ b/packages/core/src/api/api/resources/commons/types/TraceWithDetails.ts
@@ -8,11 +8,11 @@ export interface TraceWithDetails extends LangfuseAPI.Trace {
   /** Path of trace in Langfuse UI */
   htmlPath: string;
   /** Latency of trace in seconds */
-  latency: number;
+  latency?: number | null;
   /** Cost of trace in USD */
-  totalCost: number;
+  totalCost?: number | null;
   /** List of observation ids */
-  observations: string[];
+  observations?: string[] | null;
   /** List of score ids */
-  scores: string[];
+  scores?: string[] | null;
 }
diff --git a/packages/core/src/api/api/resources/commons/types/TraceWithFullDetails.ts b/packages/core/src/api/api/resources/commons/types/TraceWithFullDetails.ts
index abcc6c5a..01fb2417 100644
--- a/packages/core/src/api/api/resources/commons/types/TraceWithFullDetails.ts
+++ b/packages/core/src/api/api/resources/commons/types/TraceWithFullDetails.ts
@@ -8,9 +8,9 @@ export interface TraceWithFullDetails extends LangfuseAPI.Trace {
   /** Path of trace in Langfuse UI */
   htmlPath: string;
   /** Latency of trace in seconds */
-  latency: number;
+  latency?: number | null;
   /** Cost of trace in USD */
-  totalCost: number;
+  totalCost?: number | null;
   /** List of observations */
   observations: LangfuseAPI.ObservationsView[];
   /** List of scores */
diff --git a/packages/core/src/api/api/resources/commons/types/Usage.ts b/packages/core/src/api/api/resources/commons/types/Usage.ts
index e516fb12..1380892c 100644
--- a/packages/core/src/api/api/resources/commons/types/Usage.ts
+++ b/packages/core/src/api/api/resources/commons/types/Usage.ts
@@ -2,19 +2,18 @@
  * This file was auto-generated by Fern from our API Definition.
  */
 
-import * as LangfuseAPI from "../../../index.js";
-
 /**
  * (Deprecated. Use usageDetails and costDetails instead.) Standard interface for usage and cost
  */
 export interface Usage {
   /** Number of input units (e.g. tokens) */
-  input?: number;
+  input: number;
   /** Number of output units (e.g. tokens) */
-  output?: number;
+  output: number;
   /** Defaults to input+output if not set */
-  total?: number;
-  unit?: LangfuseAPI.ModelUsageUnit;
+  total: number;
+  /** Unit of measurement */
+  unit: string | null;
   /** USD input cost */
   inputCost?: number;
   /** USD output cost */
diff --git a/packages/core/src/api/api/resources/observationsV2/client/Client.ts b/packages/core/src/api/api/resources/observationsV2/client/Client.ts
index 565754b1..f63f04f1 100644
--- a/packages/core/src/api/api/resources/observationsV2/client/Client.ts
+++ b/packages/core/src/api/api/resources/observationsV2/client/Client.ts
@@ -74,7 +74,7 @@ export class ObservationsV2 {
    * - `basic` - name, level, statusMessage, version, environment, bookmarked, public, userId, sessionId
    * - `time` - completionStartTime, createdAt, updatedAt
    * - `io` - input, output
-   * - `metadata` - metadata
+   * - `metadata` - metadata (truncated to 200 chars by default, use `expandMetadata` to get full values)
    * - `model` - providedModelName, internalModelId, modelParameters
    * - `usage` - usageDetails, costDetails, totalCost
    * - `prompt` - promptId, promptName, promptVersion
@@ -113,6 +113,7 @@ export class ObservationsV2 {
   ): Promise<core.WithRawResponse<LangfuseAPI.ObservationsV2Response>> {
     const {
       fields,
+      expandMetadata,
       limit,
       cursor,
       parseIoAsJson,
@@ -136,6 +137,10 @@ export class ObservationsV2 {
       _queryParams["fields"] = fields;
     }
 
+    if (expandMetadata != null) {
+      _queryParams["expandMetadata"] = expandMetadata;
+    }
+
     if (limit != null) {
       _queryParams["limit"] = limit.toString();
     }
diff --git a/packages/core/src/api/api/resources/observationsV2/client/requests/GetObservationsV2Request.ts b/packages/core/src/api/api/resources/observationsV2/client/requests/GetObservationsV2Request.ts
index b5299530..3c938642 100644
--- a/packages/core/src/api/api/resources/observationsV2/client/requests/GetObservationsV2Request.ts
+++ b/packages/core/src/api/api/resources/observationsV2/client/requests/GetObservationsV2Request.ts
@@ -16,6 +16,13 @@ export interface GetObservationsV2Request {
    * Example: "basic,usage,model"
    */
   fields?: string;
+  /**
+   * Comma-separated list of metadata keys to return non-truncated.
+   * By default, metadata values over 200 characters are truncated.
+   * Use this parameter to retrieve full values for specific keys.
+   * Example: "key1,key2"
+   */
+  expandMetadata?: string;
   /** Number of items to return per page. Maximum 1000, default 50. */
   limit?: number;
   /** Base64-encoded cursor for pagination. Use the cursor from the previous response to get the next page. */