fix(backends): mapCommonBackendEvent unwraps sandbox-SDK data.part.text natively (closes #35)#36
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…ext` natively Closes #35. The canonical `@tangle-network/sandbox` `box.streamTask` emits `message.part.updated` with the text nested under `data.part.text`: { type: 'message.part.updated', data: { part: { type: 'text', text: '…' } } } Before this fix, the default `mapCommonBackendEvent` only walked `data.text` / `data.delta` / `record.text` — sandbox-SDK text deltas silently dropped out of the canonical stream, forcing every sandbox-SDK consumer (blueprint-agent#1758, future gtm-agent sandbox path, every sandbox-hosted product downstream) to ship a duplicated `mapEvent` shim that walked `data.part.text` themselves. Fix: the `message.part.updated` branch now ALSO walks `data.part.text` when `data.part.type === 'text'` (or undefined for forward-compat). Resolution order is `data.text` → `data.delta` → `record.text` → `data.part.text` so any consumer already passing the flat shape keeps working unchanged (covered by the new precedence test). Two new tests pin the behaviour: - "unwraps the @tangle-network/sandbox `data.part.text` shape natively" — fires the real sandbox-SDK shape through `runAgentTaskStream` and asserts the canonical `text_delta` stream contains `['hello', ' world']`, plus that a non-text part-kind drops cleanly (does NOT mis-fire as a text_delta). - "prefers explicit `data.text` when both shapes present" — back-compat: any existing call site sending `{ data: { text } }` keeps winning over the nested shape. Result: products consuming the sandbox SDK can wire it straight into `createSandboxPromptBackend` without writing a `mapEvent` shim — the default does the right thing. Blueprint's pinned contract test (blueprint-agent#1758, `Claude-Code → RuntimeStreamEvent migration seam`) that documented this gap as a finding now becomes the regression guard on this fix. Verification ──────────── - `pnpm test` — 181/181 pass (+2 new). - `pnpm typecheck` — clean.
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…boxEvent shape (post-#36) (#37) The example previously sidestepped the actual sandbox-SDK event shape by emitting flat `{ type: 'text_delta', text }` — which the default mapper trivially passes through. That dodged the load-bearing question products consuming the real SDK actually hit: how does `createSandboxPromptBackend` handle the canonical shape `{ type: 'message.part.updated', data: { part: { type: 'text', text } } }`? After #36 (closes #35), the default `mapCommonBackendEvent` handles this natively. This example now demonstrates the canonical pattern verbatim so consumers can copy it into their product code without guessing: - `streamPrompt` yields `SandboxEvent`s (the actual SDK shape). - Text deltas arrive as `message.part.updated` with `data.part.text` nested — no per-product `mapEvent` shim required. - Tool turns arrive as `tool_call` + `tool_result` with `data.name` + `data.input` / `data.output` — also handled by the default. Header comment + inline comments call out exactly which event variants the default mapper handles, and explicitly note that `mapEvent` is optional and only needed for product-specific shapes outside the canonical vocabulary. Verified by running the example end-to-end: pnpm exec tsx examples/sandbox-stream-backend/sandbox-stream-backend.ts emits the canonical RuntimeStreamEvent sequence — `task_start`, `readiness_*`, `session_created`, `backend_start`, **`text_delta`** (x3, from the nested `data.part.text` shape — the bit that was broken pre-#36), `tool_call`, `tool_result`, `backend_end`, `task_end`, `final`. The full vocabulary the README documents.
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Closes #35.
What
mapCommonBackendEventnow unwraps the canonical@tangle-network/sandboxmessage.part.updatedshape{ data: { part: { type: 'text', text } } }natively. Before this fix, the default mapper only looked atdata.text/data.delta/record.text— sandbox-SDK text deltas silently dropped out of the canonical stream, forcing every sandbox-SDK consumer to ship a duplicatedmapEventshim.How
if (type === 'message.part.updated' || type === 'text_delta' || type === 'delta') { - const text = stringValue(data.text) ?? stringValue(data.delta) ?? stringValue(record.text) + const part = data.part as Record<string, unknown> | undefined + const partText = + part !== undefined && typeof part === 'object' && (part.type === 'text' || part.type === undefined) + ? stringValue(part.text) + : undefined + const text = stringValue(data.text) ?? stringValue(data.delta) ?? stringValue(record.text) ?? partTextResolution order is
data.text→data.delta→record.text→data.part.textso any consumer already passing the flat shape keeps winning (back-compat).Tests
Two new tests in
tests/runtime.test.ts:data.part.textshape natively" — fires the real sandbox-SDK event shape throughrunAgentTaskStreamand assertstext_deltaevents emit['hello', ' world']. Also asserts a non-text part-kind drops cleanly (does NOT mis-fire).data.textwhen both shapes present" — back-compat guard: existing call sites sending the flat shape continue to win.181/181 full suite passes. Typecheck clean.
Why this matters
The sandbox SDK is the canonical sandbox interface for the Tangle ecosystem. Every sandbox-hosted agent product that bridges
box.streamTask→runAgentTaskStreamneeds this. Without the fix, each product ships its ownmapEventshim — exactly the duplication class agent-eval#82/#86 closed for cell helpers, but at the more load-bearing event-mapping seam (every chat-turn event passes through here).Downstream
Claude-Code → RuntimeStreamEvent migration seam) ships a pinned contract test that asserted the BUG (default mapper drops nested shape) as a finding. Once this lands + publishes, that test flips to assert the FIX — instant regression guard.