deepseek-ai/deepseek-harness · error

subagent-not-found

subagent-not-found

Error message

session "${childSessionId}" is not a ${mode} direct child of "${parentSessionId}"

What it means

Error "session "${childSessionId}" is not a ${mode} direct child of "${parentSessionId}"" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/host/apiproxy/src/api-proxy.ts:2575

          if (error instanceof SubagentError && error.code === 'SUBAGENT_CONTROL_PROJECTIONS_UNAVAILABLE') {
            return err(request, projectionsUnavailableError())
          }
          return err(request, {
            code: 'internal',
            message: 'subagent catalog read failed',
            details: {},
          })
        }
      },

      async history(request, signal) {
        const {
          parentSessionId, childSessionId, mode, beforeSeq, maxMessages,
        } = request.payload
        const verified = await catalogChild(ctx, {
          parentSessionId, childSessionId, mode,
        }, signal)
        if (verified.error !== undefined) return err(request, verified.error)
        // The generic-history data plane: an attached child serves its
        // in-memory snapshot and the registry's live watermark projections; a
        // cold child is one persistence inspection plus a detached fold.
        let header: SessionHeader
        let events: SessionEvent[]
        let projections: SessionProjectionsBlock | undefined
        const attached = ctx.sessions.get(childSessionId)
        if (attached !== undefined) {
          header = attached.header
          events = [...attached.events]
          projections = beforeSeq === undefined
            ? subagentHistoryProjections(ctx, childSessionId, () => projectionsFor(ctx, attached))
            : undefined
        } else {
          try {
            const inspected = await inspectServable(childSessionId)
            header = inspected.meta
            events = inspected.events

View on GitHub (pinned to b150a551b8)

Solutions

1. Use the correct parent and child session ids; the child must be a direct child of the parent in the given mode.

When it happens

Trigger: Thrown at packages/host/apiproxy/src/api-proxy.ts:2575 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of deepseek-ai/deepseek-harness@b150a551b8 (2026-08-24). Data as JSON: /api/errors/0470a0f630d68a54. Report an issue: GitHub.