Basis

Add a new sheet to a session's workbook. The new sheet becomes the active sheet. Only works on sessions created from blank documents (not imported xlsx files).

Run a comprehensive audit of a session's workbook. Returns statistics on sheets, cells, formulas, errors, named ranges, and the dependency graph. Use to get an overview of model structure before making changes.

Close a computation session and release its resources.

Create a named checkpoint of the session's current state. Returns the commit ID which can be passed to restore_session to roll back. Checkpoints live in the session only; to keep one in the Library's version history, call save_to_library after it (the version takes this message as its name).

Create a persistent computation session for a workbook. Pass path/base64/url for xlsx input, or omit all for a blank model. Returns a session_id for subsequent calls. The workbook is uploaded to the Basis API and held there for the session. Pass library_file_id instead to open a file from your Library.

Create or retarget a named variable in the session's workbook.

Compare two .xlsx workbooks and return the cell-level differences as JSON. Both files are parsed on the Basis API, joined on (sheet title, cell ref) and classified into added, removed, and changed (value and/or formula), with format-only changes bucketed separately. Provide exactly one of before_path/before_url/before_base64 and one of after_path/after_url/after_base64.

Evaluate an Excel formula and return the computed result. Pass data as a map of cell references to values (e.g. {"A1": 100, "A2": 200, "B1": "hello"}) and a formula string (e.g. "SUM(A1:A2)"). The formula is placed in the first unused cell and recalculated. Supports 276 Excel functions: math, financial (NPV, IRR, XIRR, PMT, PRICE, YIELD…), statistical distributions, regression, lookup, date/time, text, logical, and dynamic arrays (FILTER, SORT, UNIQUE, SEQUENCE, CHOOSECOLS, TAKE, DROP). Runs on the Basis API (needs an API key).

Read the formula source text and computed value for a single cell in a session. Returns whether the cell contains a formula, the formula text (with = prefix), the computed value, and value type. Use to inspect what a cell actually computes.

Batch-read formulas and computed values for a rectangular range of cells. Returns an array of {cell, formula, value, value_type} for each cell in the range. Much more efficient than calling get_cell_formula repeatedly.

Check the status of a parse job submitted via submit_job.

Read computed values from a session. Pass specific names/refs, or omit to read all defined names.

Inspect a session's model structure: sheets, defined names, stats, and optionally dependency edges.

List all active computation sessions.

Parse an .xlsx workbook on the Basis API and return the full semantic NDJSON output (workbook_meta, sheet, cell, edge, image, image_summary, audit records). Handles small vs. large files transparently. The file is uploaded to the Basis API.

Rename a sheet in a session's workbook. Formulas, named ranges and validations that reference the sheet are rewritten to the new name, so results don't change. Excel's rules apply: 1-31 characters, none of : \ / ? * [ ], no leading or trailing apostrophe, unique ignoring case.

Roll back a session to a previous commit. Reverts all cell changes made since that commit. Returns the number of cells that were changed by the rollback.

Save the session's workbook to the user's Library for durable storage. If the session was loaded from the Library or was previously saved, this creates a new version of that file. Otherwise it creates a new Library file. Each save is a named version in the Library's history: pass `message`, or it takes the latest commit_session message since the last save. commit_session checkpoints themselves stay in the session, so save after each step you want kept as a version. Requires a Basis API key. Returns the library_file_id.

Turn iterative calculation on or off for a session and recalculate. Needed for circular models (e.g. development pro formas where loan size depends on cost, which includes the loan's interest and fees): with it on, set_inputs re-converges the loop on every call. Saved with the session's next commit (restore_session to an earlier commit rolls it back) and written to the workbook, so an exported xlsx iterates in Excel too.

Set one or more input values in a session and recalculate. Keys can be defined names or cell references. Returns applied changes and which named outputs changed (effects).

Export the session's current state as xlsx bytes (base64). Optionally creates a commit first.

Fetch the NDJSON output of a completed parse job. Pass `since` to resume from a record index.

Submit an .xlsx workbook to the Basis API for async parsing and get back a job handle (job_id, status_url, stream_url) without waiting for it to finish.

Trace the formula dependency graph for a cell in a session. Returns precedents (cells this cell references) and/or dependents (cells that reference this cell), with their formulas and values. Use to understand calculation chains, debug circular refs, and find the root cause of errors.