{"record":{"id":"5c3861333c604e23","repo":"deepseek-ai/deepseek-harness","slug":"location-uses-unsupported-legacy-request-header","errorCode":null,"errorMessage":"${location} uses unsupported legacy request/header-delta format","messagePattern":"(.+?) uses unsupported legacy request/header-delta format","errorType":"validation","errorClass":"Error","httpStatus":null,"severity":"error","filePath":"packages/core/session/src/index.ts","lineNumber":365,"sourceCode":"    throw new Error(`${subject} message must contain one tool-result block`)\n  }\n  if ((block as Record<string, unknown>)['toolCallId'] !== sourceRecord['callId']) {\n    throw new Error(`${subject} message has mismatched tool call ids`)\n  }\n}\n\n/** Whether an unknown value carries the current provider/model pair. */\nfunction hasProviderModel(value: unknown): boolean {\n  if (typeof value !== 'object' || value === null) return false\n  const pair = value as Record<string, unknown>\n  return typeof pair['provider'] === 'string' && pair['provider'].length > 0\n    && typeof pair['model'] === 'string' && pair['model'].length > 0\n}\n\n/** Reject request-header vocabulary removed with the legacy delta codec. */\nfunction assertSupportedRequestHeader(type: string, data: unknown, location: string): void {\n  if (type === 'request/header-delta') {\n    throw new Error(`${location} uses unsupported legacy request/header-delta format`)\n  }\n  if (type === 'request/header'\n    && data !== null && typeof data === 'object' && !Array.isArray(data)\n    && (data as Record<string, unknown>)['reason'] === 'fallback') {\n    throw new Error(`${location} uses unsupported legacy request/header reason \"fallback\"`)\n  }\n}\n\ntype SessionCallback = (...args: unknown[]) => unknown\n\n/** Resolve one listener snapshot, including Cordis's internal dispatch checks. */\nfunction collectSessionCallbacks(ctx: Context, args: unknown[]): SessionCallback[] {\n  return [...ctx.events.dispatch('emit', args)] as SessionCallback[]\n}\n\n/** Invoke one resolved observe-only listener snapshot with per-listener containment. */\nfunction invokeContainedSessionObservers(\n  ctx: Context,","sourceCodeStart":347,"sourceCodeEnd":383,"githubUrl":"https://github.com/deepseek-ai/deepseek-harness/blob/b150a551b8d465e31e418e1b2eaf5e79bbb7d28e/packages/core/session/src/index.ts#L347-L383","documentation":"Error \"${location} uses unsupported legacy request/header-delta format\" thrown in deepseek-ai/deepseek-harness.","triggerScenarios":"Thrown at packages/core/session/src/index.ts:365 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Migrate the legacy request/header-delta format at the reported location."],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"b150a551b8d465e31e418e1b2eaf5e79bbb7d28e","analyzedAt":"2026-08-24T18:12:29.105Z","schemaVersion":2},"datasetVersion":"2026-08-24T22:17:12.610Z"}