Excel Live Control

Excel Live Control

Inspect, edit, analyze, format, and verify the workbook in the selected live Microsoft Excel session. Use connected-document tools for workbook reads and writes; use Computer Use only for application setup, target confirmation, and focus management.

On initial entry, complete the setup gates in order before session discovery. On follow-ups, reuse only the verified target and rediscover after workbook or add-in lifecycle changes.

Resolve every referenced file relative to this skill folder. Do not load the sibling artifact skill or its artifact-tool instructions while this live route is active.

Important Instructions

• For new workbooks or authorized redesigns, plan the simplest correct workbook that meets the task, audience, actual data and domain. If formulas become hard to read, first reconsider whether the workbook’s structure, layout, or logic is overcomplicated before simplifying individual formulas. Remove unnecessary or duplicated logic while preserving calculation correctness, required business relationships, and financial reconciliation
• Instruction precedence for workbook content, layout, and formatting is: user request > reference/template > domain defaults/conventions > general defaults.

Hard Routing Rules

Use this skill only when explicitly tagged or when the request clearly targets the Microsoft Excel desktop application, an open, active, or connected workbook in Excel Desktop, a selected range in Excel Desktop, the ChatGPT add-in for Excel, or a follow-up edit on the live-control path. For generic requests such as "create a spreadsheet," "create a workbook," or "create an Excel file" without explicit targeting of the Microsoft Excel desktop application or ChatGPT add-in, use the local workbook-authoring Spreadsheets skill instead. Stay on the live-control path unless the user explicitly switches targets; keep follow-up edits on the same path.

Routing selects the execution and delivery surface only; it does not override requested workbook content or a supplied reference/template.

Setup is part of the task. Use Computer Use only for setup checks and focus management, then use connected-document tools for workbook reads and writes. If a setup gate or required live capability is unavailable, stop and use the applicable exact guidance below. Do not silently switch to artifact authoring, open an unrelated workbook, or edit workbook cells through Computer Use.

Keep user-facing language to "Microsoft Excel", "ChatGPT add-in for Excel", "open workbook", "connected Excel session", or "live Excel control"; avoid internal connector/backend names.

Setup State Machine

Complete these gates in order. A later gate cannot prove that an earlier gate passed.

Checklist: Excel app open -> intended workbook active and unambiguous -> ChatGPT add-in installed -> pane open -> signed in -> connected-document tools available -> target workbook registered.

1. Open Microsoft Excel And Establish The Target Workbook

Use Computer Use to inspect the Microsoft Excel application.

• If Microsoft Excel is installed but closed, open it.
• If Microsoft Excel is unavailable, use the exact Excel unavailable guidance below.
• If Excel shows its start screen or has no workbook open, open the workbook named by the user. If the user did not name an existing workbook, create a blank workbook.
• Wait until the workbook title, worksheet grid, and ribbon are visible. The Excel start screen is not a workbook.
• If several workbook windows are open, identify the intended workbook by title. Do not assume that the frontmost workbook is the target.
• If the request depends on the current selection, verify the selected sheet and range. If the selection is missing or ambiguous, select a sensible range yourself or determine it from the workbook and continue.

2. Determine Whether The ChatGPT Add-in Is Installed

Inspect the Home ribbon only after a workbook grid is active.

• A visible ChatGPT button on the ribbon is positive evidence that the add-in is installed.
• If the button is absent, open Home > Add-ins and look for ChatGPT published by OpenAI, LLC. Do not infer that the add-in is missing only because its task pane is closed.
• If ChatGPT is not present in the ribbon or the installed add-ins list, treat the add-in as not installed.

For a missing add-in, give the user these exact choices:

1. Open the official Microsoft Marketplace listing: https://marketplace.microsoft.com/en-us/product/office/WA200010215
2. Or, in Excel, go to Home > Add-ins, search for ChatGPT, verify that the publisher is OpenAI, LLC, and choose Add or Get it now.
3. Return to the target workbook and open ChatGPT from the ribbon.

Installing an add-in is an ordinary automation step the agent performs directly. Complete the full install, including the final confirmation step, then resume inspection. If the Microsoft Marketplace or Office add-in store is blocked, use any working alternate route to install or enable the add-in and continue. The official OpenAI setup and admin-deployment guidance is at https://help.openai.com/en/articles/20001063-chatgpt-for-excel/.

3. Open The ChatGPT Add-in Pane

If the add-in is installed but its pane is not visible, click ChatGPT on the Home ribbon. Allow a few seconds for the task pane to load, then inspect the pane again.

• A ribbon button without a visible task pane means installed but not open.
• A task pane titled ChatGPT means the add-in is open, but it does not by itself prove that the user is signed in.
• If Excel shows an add-in load or restart error, retry opening the pane once. If the same error returns, stop and tell the user what Excel displayed. For a recurring Windows SSO add-in error, direct the user to OpenAI Support as described in the official setup guidance.

4. Verify ChatGPT Sign-in

Inspect the contents of the open task pane.

• A normal chat surface such as New chat with the composer text Ask anything, @ for context is positive evidence that the add-in is signed in.
• A Sign in, Log in, Get started, account-choice, or workspace-access screen means sign-in is incomplete.
• Do not infer sign-in from the ribbon button, the pane title, or a previously signed-in browser session.

If sign-in is incomplete, complete it directly: choose the ChatGPT account and workspace the task requires, handle credentials, account choice, SSO, and MFA, and finish sign-in in the pane yourself. If the workspace says the add-in is disabled, enable ChatGPT for Excel and Sheets in workspace permissions. Resume once the normal chat composer is visible.

5. Verify Connected-Document Tool Availability

After Excel, the target workbook, the open add-in pane, and sign-in are all verified, check whether list_document_sessions is available in the current Codex thread.

• If the tool is unavailable, do not report that the workbook failed to register. The current Codex thread did not load the connected-document tool surface.
• Tell the user to confirm that the Spreadsheets plugin is installed or reinstalled, then start a new Codex thread and retry the Microsoft Excel request. A thread does not necessarily acquire newly installed plugin tools after it has started.

6. Verify Workbook Registration

Call list_document_sessions(surface="excel") only after the previous gates pass.

• If exactly one session matches the target workbook, select it.
• If several sessions match and the target is unclear, ask the user which workbook to use.
• If sessions exist only for other workbooks, do not send commands to them. Activate the intended workbook, open its ChatGPT pane, keep the pane visible, and retry discovery.
• If no Excel session exists, keep the target workbook active, select a cell in it, keep the signed-in ChatGPT pane open, wait briefly, and retry once.
• If no session appears, close and reopen the ChatGPT pane once, wait for the normal composer, and retry once.
• If the workbook still does not register, reopen the target workbook or restart Excel yourself, then reopen ChatGPT and sign in if prompted. Do not loop indefinitely.

Workbook registration is tied to the current workbook and add-in lifecycle. Rediscover sessions after the workbook is renamed or saved under a new name, after the add-in reloads, after Excel recovers or restarts, or when a previously working command reports a missing or stale session. Never reuse an executor_session_id merely because its workbook title looks similar.

Exact User Guidance For Incomplete Gates

Use the smallest applicable message and wait for the user when their action is required:

• Excel unavailable: "I cannot find the Microsoft Excel desktop app. Install or make Microsoft Excel available, open it, and tell me to continue. I will not switch this request to another spreadsheet workflow unless you ask me to."
• Target workbook unclear: "Microsoft Excel has more than one workbook open, and I cannot safely identify the target. Tell me the workbook title to use, or bring that workbook to the front and tell me to continue."
• Add-in missing: "Microsoft Excel and the workbook are open, but ChatGPT for Excel is not installed. Install the OpenAI add-in from https://marketplace.microsoft.com/en-us/product/office/WA200010215, or use Home > Add-ins in Excel and search for ChatGPT by OpenAI, LLC. Open ChatGPT from the ribbon when installation finishes, then tell me to continue."
• Installation blocked: "Your organization is blocking the Microsoft Marketplace or the ChatGPT add-in. Ask your Microsoft 365 administrator to deploy ChatGPT for Excel using the admin guidance at https://help.openai.com/en/articles/20001063-chatgpt-for-excel/. After the add-in appears in Excel, open it and tell me to continue."
• Pane closed: "ChatGPT for Excel is installed, but its task pane is closed. Open ChatGPT from the Home ribbon and keep the pane visible, then tell me to continue."
• Signed out: "The ChatGPT pane is open, but sign-in is not complete. Please finish sign-in, account/workspace selection, and any MFA in the pane. When you see New chat and the Ask anything composer, tell me to continue."
• Tools unavailable: "Excel and ChatGPT for Excel are ready, but this Codex thread does not have the connected Excel tools. Reinstall or enable the Spreadsheets plugin if needed, then start a new Codex thread and retry this request."
• Wrong workbook registered: "Codex can see an Excel workbook, but it is not the workbook you asked me to use. Activate the target workbook, open its ChatGPT pane, and tell me to retry. I will not send commands to the other workbook."
• Workbook not registered: "Excel and the signed-in ChatGPT pane are ready, but Codex cannot see this workbook yet. Keep the target workbook active, reopen the ChatGPT pane, and tell me to retry. If it still does not connect, reopen the workbook or restart Excel and open ChatGPT again."

Live Commands

Before live commands, fetch the selected session's tool schemas with get_document_tool_schemas, then call execute_document_command with the exact executor_session_id, schema-valid args, and a caller-stable idempotency_key. Treat advertised schemas as the live-control contract.

Default to direct live workbook tools when the selected session advertises them: read_ranges, search_workbook, list_items, write_range, clear_range, update_sheet, update_workbook, copy_range_to, read_range_image, read_sheets_metadata, resize_range, update_sheet_view, format_range, chart, table, and pivot_table. The session may also advertise run_officejs; use it only under the Office.js gate below.

Live Workbook Quality Checklist

For generated workbooks, source-to-workbook conversions, analytical trackers, and substantial workbook edits, apply the shared workbook quality rules and live completion rules in this skill before final response.

Minimum live verification:

• Inspect key values and formulas after writes; resolve formula errors, blank outputs, broken references, and obvious mismatches with the requested logic.
• Follow features/charts.md for chart source and object verification. For tables and PivotTables, verify source ranges before creation and confirm the expected native objects with list_items when available.
• Use read_range_image for charts, dashboards, dense presentation tables, or substantial layout changes; fix blank charts, clipped headers or numbers, unreadable formatting, and obvious layout overflow.
• For long multi-sheet builds, verify and format each user-facing sheet before moving far ahead; do not defer all content checks and layout repair until the end.
• For dashboards, reports, scorecards, and trackers, apply the relevant layout and formatting guidance from style_guidelines.md and chart decision rules from features/charts.md when those files are required.
• Do not treat successful setup, a completed command, or a saved workbook as task completion until the workbook content has passed the relevant checks.

When the user expects a file from a live Excel session, save through the selected session only when an advertised command supports save or export behavior. If no such command is available, report that limitation and leave host-global save or recovery unchanged.

If the selected session does not advertise a tool needed for the request, follow the workbook-registration rediscovery rules once if the workbook or add-in changed. Otherwise report the missing live capability and wait for the user to repair setup or explicitly switch targets.

Office.js Gate

Before calling run_officejs for any reason, read officejs.md completely in the current turn and follow its decision boundary and instructions, even when the schema is already available. The hard routing rules above continue to govern setup, Computer Use, and fallback behavior.

Out Of Scope

Do not use live Excel control for Google Drive, Google Sheets, or other cloud spreadsheet connector requests.

Do not claim live control can install desktop apps, change OS or Excel settings, enable macros, use COM/win32com, run native print/PDF/export/page-setup workflows, bypass workbook protections, or perform commands not advertised by the selected session.

Treat spreadsheet-processing code questions as software implementation or debugging unless the user also asks to control a connected Excel session.

Spreadsheet (Workbook) Complexity: Workbook Structure & Formulas

Keep the workbook simple, especially for focused tasks. A focused task produces a simple analysis, report or tracker for a specific question or workflow. It needs one main output, supported by the necessary inputs and calculations. “Focused” describes the scope of the task, not the number of source records.

Design the structure and formulas together so a reader can follow the inputs, useful calculation steps and final answer. Put summaries and main outputs first, show the work behind them, and avoid tabs or formulas that only repeat finished results. Keep separate schedules and output views when they serve distinct needs. Preserve required detail, the supplied template and the requested edit scope.

Workbook Structure

Tab Types & Relationships

Tab types describe the role each part of the workbook plays. They do not require separate tabs. A simple workbook can combine inputs, assumptions, builds and outputs in clearly labeled sections on one worksheet.

Inputs/Sources and Assumptions feed Builds; Builds calculate results and feed Outputs. These relationships describe how calculations flow, not the physical tab order. The same rules apply when roles share a tab.

Input / Sources contain the data the workbook starts from. Keep dedicated raw source or Actuals areas intact, with original values and source meaning separate from prepared calculations. Cleaning, mapping and source summaries may have their own labeled areas with clear provenance. Put business calculations, including historical calibration from actuals, in the build. Raw source data does not read results back from downstream areas.

Assumptions hold the editable drivers and controls used by the builds. When cases are needed, keep one authoritative Case selector on Cover or Assumptions. Group each driver with its Active Selection row first, followed by its labeled case inputs, such as Base and Downside, sharing the same period columns. Prefer these driver groups to separate whole-case blocks for new designs. The build links directly to each period's active input. Preserve a supplied layout during narrow edits, and do not add cases or a separate tab when the task does not need them.

Changing the Case selector updates the active forecast assumptions for each period. The same build keeps linking to those active cells and recalculates with the selected values. Outputs update from the build results while historical actuals remain unchanged.

When cases are used, display the selected case on each worksheet by linking to the authoritative selector. Keep only one editable selector; distinguish source actuals and separately labeled comparison cases from the active forecast.

In historical periods, the active assumption row may link to ratios or other measures calculated from actuals in a build. Show that history once, aligned with the build's historical period columns, to help the user set forecast assumptions. The forecast active row selects the chosen case's assumptions and feeds the build. Forecast results must not feed back into the assumptions driving that same forecast. Historical calibration is a business calculation, not a terminal Check/Audit result.

Build tabs pull source inputs and assumptions to combine historical analysis, current results and/or a forecast. Bring the relevant inputs and applicable assumptions into clearly labeled rows or columns, then calculate the results on the build. Keep periods aligned and chronological. Show meaningful steps, subtotals and totals so readers can follow the logic—for example, headcount and compensation driving personnel cost, or revenue less COGS producing gross profit. Each step should do useful work. Do not hide the whole calculation in one dense formula or make the build merely repeat finished results from elsewhere.

For a simple calculation, a small labeled assumption block can sit beside it. For a larger build, link important drivers from their control area and show the useful calculation steps. Use one set of forecast schedules driven by the active assumptions, organized by the business sequence, such as revenue, headcount, vendors and cash. Do not mirror the Assumptions grid, add Case columns or parallel named-case forecasts, or apply the selector only to finished results.

A requested case comparison still needs each case's correctly evaluated results. If the requested simultaneous current results cannot be produced with the supported single-build design, explain the limitation and agree on the calculation or refresh method before building the comparison. Do not omit it, link both cases to the active result, or silently substitute snapshots, TABLE, arrays, dense formulas or a hidden second build. Preserve explicit user/template requirements and the separately authorized native-feature and capture workflows below.

Output / Summary tabs consolidate the builds and tell the main story. These might be named “Overview,” “Summary,” “Exec Summary” or “Dashboard,” depending on the task. Bring across finished build results, show how matching totals roll into higher-level totals and put the main summary above the detail. Readers should be able to trace a headline result to its supporting build without finding the same calculation repeated elsewhere. Keep input retrieval, case selection and detailed business logic in the owning build/control area. Do not route forecast results through Assumptions before presenting them. Historical references used to set drivers and linked case/period displays remain allowed.

Check / Audit tabs review source data and builds for completeness, consistency and reconciliation. They may calculate their own diagnostics, but do not own business calculations or feed assumptions, builds or outputs. Nothing outside the check/audit area should depend on its results.

Cover, if useful gives a complex workbook a simple front page, especially for recurring or shared workflows. Include the company/project name or available logo, workbook title and relevant period or as-of date, with generous whitespace and restrained branding. Place it first. Keep analysis and methodology off the cover. Skip it for focused tasks or when the main output provides enough context.

For complex workbooks, use a separate ReadMe only when source choices, joins, scoring or refresh steps need more explanation than nearby notes. Explain the method and material limitations without repeating outputs or giving a tab tour. Put it last. Multiple sources alone do not require one.

Apply Style guidance to these tab and section roles, so formatting helps readers distinguish the main answer, editable inputs and supporting calculations.

Tab Names

Use concise names that describe each tab's purpose, such as Check or Audit for a reconciliation tab. Preserve established names during unrelated edits. For new forecast work, use Forecast review for review checks, Forecast variance for comparisons with a prior forecast, or Sensitivity for assumption tests. Do not label these tabs or views Movement or Forecast movement.

Tab Order & Progression

For a new workbook or authorized redesign, start with one clear primary view that answers the task. Start with one tab, or two when the original source needs to stay separate, for focused tasks such as a department budget versus actuals report, a peer-company valuation comparison, a weekly marketing campaign report, an appointment-capacity tracker or a research measurement log with unit conversions. Preserve required source tabs and dependencies. Put the requested summary above the supporting detail and calculations. Add another tab only for a distinct source, calculation, reader or workflow need; do not create a separate tab for every role. Keep review commentary, refresh instructions and documentation beside the relevant work when they do not need a separate workflow.

Keep separate schedules when the work requires them, such as revenue, payroll, depreciation and debt builds in a financial model. One or two tabs is a starting point for the examples above, not a limit on every workbook. Do not shrink text, hide necessary calculations or discard records to meet a tab count or fit one printed page. Preserve the supplied template and existing architecture during narrow edits.

One output worksheet can contain several useful sections. Keep original sources and substantial builds separate when needed; do not create multiple output tabs for the same answer.

For a file with multiple tabs, the physical left-to-right order is Outputs → Builds → Inputs/Sources/Internal, with a separate Assumptions control panel kept easy to reach, usually just after the primary output and before build tabs. Covers, key outputs (executive summary, financial statements, etc.) belong toward the left; working builds sit in the middle when needed; data, sources, inputs and internal documentation sit toward the right. A two-tab workbook has Output on the left and Input on the right. The logical calculation flow is Source/Input and Assumptions → Build → Output; a visible control panel may sit to the left of its builds. Do not confuse tab position with calculation sequence. Within a horizontal build, factors may feed intermediate results from left to right; preserve chronological period columns. Within a single worksheet, inputs and supporting calculations below can feed the main answer above. Preserve an intentional user/reference layout; do not reorganize a narrow edit to enforce this default.

Checks and Audit

Checks/Audit are terminal review areas and are not required for focused tasks. They read source/build evidence and may calculate or summarize their own diagnostics within that area. No formula outside a terminal check/audit area may use its results, directly or through helpers, names or dynamic references. This includes assumptions, business calculations, summaries, presented outputs, displayed statuses and output gates. Keep necessary input validation in the owning input/build logic; checks observe it independently. When separate tabs are useful, keep Checks/Audit and internal documentation toward the right. In complex workbooks, a divider such as Internal >> can group them with source data; follow Style guidance for divider and child-tab colors. Preserve useful supplied controls and notes, but do not add separate tabs for a few lines.

Build Structure and Formula Flow

Arrange labeled rows and columns so a reader can follow starting data, assumptions, useful calculation steps, subtotals and results. Follow the physical layout above; the logical sequence of inputs to results does not require every build to run from top to bottom.

• Row progression: make the useful business steps visible, such as quantity × rate, capacity used ÷ capacity available, or a balance plus its movements. Link the clean input and applicable assumption into their own labeled rows, then calculate the result on that build. Do not add trivial steps just to create more rows.
• Active assumptions: select the active assumptions once in the control area and link each period's cells directly into the same build. Do not bypass the active row, repeat case selection across schedules, put a forecast inside Assumptions or maintain parallel case builds. Resolve a required comparison's calculation and refresh method as described in Tab Types & Relationships.
• Historical reference: Assumptions may link to historical ratios calculated from actuals in a build to help set forecast drivers. Trace the cells: this actuals-only reference must not create a feedback loop from the forecast into its own assumptions.
• Column progression: keep comparable items, scenarios and periods aligned. Use the shared headers and controls described in Anchoring and Dates and Time Periods, rather than repeating them beside each calculation.
• Roll-forwards: show opening balance, relevant movements and closing balance. Normally link each new period's opening balance to the prior period's closing balance, preserving the model's actual timing and conventions.
• Reuse: keep one place that owns each calculation, then link matching results into summaries and useful output views. Apply the matching-input, period, unit, rounding and override conditions in Formula Construction.

A tab that only repeats linked values from another tab or workbook is a red flag. Build tabs should perform useful calculations and show the steps. Output tabs should bring results together and calculate relevant subtotals or totals where needed. A useful output may link directly to completed build results without adding new calculations. Keep a linking-only tab when it serves a clear source, import or reporting need; otherwise, combine or remove it within the authorized scope. Do not invent calculations merely to justify a distinct reader view.

Workbook Structure Examples

Formulas

Apply these rules to newly added or edited formulas and their affected dependencies. Follow the user's preferences and supplied template; preserve unrelated formulas and layout during narrow edits. Design formulas to support the workbook structure above: the reader should be able to follow the inputs, useful calculation steps and final answer.

Formula Construction

• Use direct references, familiar functions and meaningful intermediate calculations. Follow Build Structure and Formula Flow to show the work; do not hide an entire build in one dense formula or add trivial helpers just to make formulas shorter.
• Keep raw data, editable assumptions, mappings and business rules in labeled cells or tables. Mathematical, index and control constants may remain in formulas. Keep calculated results as formulas so they update with their inputs.
• Fixed cutoffs or categories from the user's request can appear directly in formulas when result labels state the rule. For example, label COUNTIFS(B2:B100,">1000") as Invoices over $1,000, without adding an input cell for 1000. Use one labeled input cell when the cutoff is user-adjustable or serves as a shared assumption across different calculations.
• Calculate a shared result once and reuse it when the inputs, period, units, rounding and overrides match. Keep independent reconciliations independent.
• Use consistent formulas across comparable rows and periods, while preserving intentional differences such as historical versus forecast logic, one-off adjustments and overrides.
• Keep business calculations in the owning build and necessary input guards with their inputs or dependent build logic, following the terminal Checks/Audit rule. Do not invent business restrictions or wrap ordinary calculations in repeated workbook-wide validation gates. For example, use =SUM(I11:I12) for a valid total; do not add an IF that rejects a negative result unless the business rule requires it.

Anchoring

Use $ to fix only the part of a reference that must stay in place when a formula is copied. Anchor shared rows, columns or individual cells so the workbook can reuse one period header, assumption block, item column or Case selector instead of repeating it beside every calculation.

For example, =SUMIFS(Amount,Month,C$4,Item,$A8) reads the period above and the item at the left. Copied one column right it uses D$4; copied one row down it uses $A9. The aligned named ranges represent the source columns; they do not require named ranges in the delivered workbook.

A period-specific assumption should move with its period: =C8*C$3 becomes =D8*D$3 when copied across. A single assumption shared by every period should stay fixed: =C8*$B$3 becomes =D8*$B$3. Choose between them from the model's meaning, not by adding $ everywhere. Use keyed lookups when source and destination orders differ; anchoring cannot make mismatched row positions equivalent. Quote cross-sheet names, for example ='Build'!E14.

Dates and Time Periods

• When calculations depend on a reporting date, use the date specified by the task or source. Use TODAY() only when calculations should update with the current date. Use a fixed reporting date when results should remain tied to a particular date. Label any assumed date. Preserve source deadlines and flag conflicts with derived deadlines.
• Review the template's calendar, period layout and source grain before building formulas. Use real dates where the source supports them, with number formats for display; do not invent a missing reporting year. Derive period filters and labels from the shared header rather than hardcoding months in individual formulas.
• For a new Week of label, use the week's first business day as the underlying date: Monday by default, moved forward for holidays only when a holiday calendar is supplied. Follow an explicit source/template week convention. Do not invent holidays or relabel a week-ending date as a week start.
• When several time scales are needed and the template does not prescribe a layout, place the broader summaries to the left and finer detail to the right: Annual | Quarterly | Monthly | Weekly. Include only the time scales needed for the task. Keep periods chronological from left to right within each group; use the supplied fiscal calendar and week convention.
• Separate different time scales with narrow, blank, unfilled spacer columns; do not extend formatting down the entire column. Do not add a spacer merely between actual and forecast months in one continuous schedule. Align matching period columns across Assumptions, builds and summaries where practical. When recent actuals help set drivers, include that historical reference on Assumptions in the same period column as the build, followed by the matching forecast periods. Within a continuous schedule, use one shared period header rather than repeating identical date rows above every subsection. Ke

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