Skip to main content
Select a call in an execution graph, then use its details panel to inspect what it received, returned or raised. Begin with the preview. Fetch a full value when you need more detail and the action is available. In the checkout example, line_total receives one order line and returns its price in cents. The first invocation receives a notebook line with quantity two. Its unit_price child returns 1200 cents, and line_total returns 2400 cents. Together, these values explain how the line contributed to the order total.

​
Select a call and data category

Use the selected call’s tabs: Select Info when you need the attempt’s status and timing. A missing output category is not an empty return value: the UI distinguishes a missing slot from an attempt that has not reported completion. An in-flight attempt has no reported value slots to fetch. For example, the pricing call’s Input tab contains its customer and order lines:
Pricing call Input tab showing the customer and order line arguments.

Recorded arguments for price_order.

Open the full-size screenshot.

​
Previews and full values

The trace response includes previews and capture metadata. Selecting Input or Output does not itself retrieve all recorded bytes. Select fetch full value to request them. The UI offers this action for stored and pending handles that have no fetched value yet. Flat JSON objects are displayed as labeled fields. Nested objects, arrays and other values use a text view. A preview can end before the full JSON value is complete; do not interpret a cut-off preview as malformed application data.
Output tab with discount, subtotal, tax and total fields for the pricing call.

The pricing call returned a total of 3208 cents.

Open the full-size screenshot. Selected input/output entries from the values response for the first line_total call:
The HTTP response carries each value as a string. Interpret it using encoding:
  • json: parse the string as JSON, such as the argument object or the number 2400 above.
  • text: the value is captured text.
  • base64: decode the value as binary bytes when using the HTTP API. The UI’s generic viewer displays text; it does not reconstruct the original Python bytes object.
The response above returns readable bytes with state: "stored". The server resolves a pending capture to stored when its bytes are readable. A trace-detail response carries previews and metadata; only a full-value request confirms whether a value reported as stored remains readable.

​
Errors and logs

In the checkout graph, authorize_payment fails against its modeled primary processor and succeeds on the next attempt. Select the failed attempt and open Error to see its exception class and error preview. The captured error value decodes to:
Payment error preview with the Other attempts control pointing to the recovered attempt.

A failed attempt with a successful other attempt.

Open the full-size screenshot. The exception belongs to that attempt, not necessarily to the entry point’s final result. The checkout root returns normally because the application handles the first payment failure. A caller can also catch an exception and return a business rejection. Read root status and attempt status separately. Error messages and logs depend on the application’s capture controls. The Python SDK’s stack representation identifies file, line number and function, without source text. A recorded line number refers to the code that produced the capture; it does not identify the application revision on its own. Logs require log capture to be enabled. After the log value is fetched, Logs displays each entry’s level, relative offset, logger name and message. A missing logs slot does not establish that the application emitted no logs: log capture is a separate control.

​
Values across attempts

Use Info or Error to select a numbered retry attempt. Status, timing and previews in the trace are attached to individual attempts. In Table, clear collapse retries to select an individual attempt directly. Full-value retrieval has a different contract. /v1/traces/{id}/values selects a call by path and a data category by slot; it has no attempt selector. Returned entries also have no attempt number. For a retried call, repeated entries can share the same path and slot. Switching attempts does not make a full-value fetch attempt-specific. Use the attempt-specific previews to compare retries; the fetched bytes cannot identify a numbered attempt. When a retained function example is available, its attempt identifies the execution. include=values retrieves that example’s input/output for the stored attempt. This lookup does not provide arbitrary access to every attempt of a trace. See Understand function usage and HTTP search and metadata.

​
Truncated, withheld and unavailable data

Captured values are bounded representations. A preview can be shorter than the stored value; a capture can also be truncated before storage because of capture limits. Fetching full bytes cannot restore data omitted during capture or reconstruct an object that was represented only by type information. Check truncated, the captured representation and the relevant SDK limits. Values can also be disabled, excluded by sampling, withheld by data controls or absent because an attempt has no completion record. Do not infer which case occurred from an empty preview. The HTTP handle does not report whether individual fields were withheld inside a captured value; inspect the representation and the capture configuration. A preview can remain after the server no longer has the full bytes. A value recorded as stored becomes expired on a full-value read when its bytes are unavailable. The store cannot distinguish bytes removed by retention from bytes that have not arrived. expired does not prove that the server once held the value. A pending capture becomes stored on a later read when its bytes are readable. If it remains pending, the response does not establish why the bytes are unavailable or whether they will become readable. Do not infer availability from recording completeness. An unresolved value omits encoding, bytes_count and truncated. A readable zero-length payload is different: it omits value and bytes_count, but keeps encoding and truncated. Do not treat an empty text return value as unavailable data. If a value is unavailable, preserve the distinction between missing data and a failed function. Use Retention for storage lifetimes, Capture controls for producer settings and HTTP traces and values for exact states and fields.