Ribbon

Ribbon brings installable ACP coding agents into Microsoft Office. Excel, Word, and PowerPoint each use a thin VSTO add-in, while one shared local broker manages the ACP Registry, agent processes, conversations, permissions, and a unified Office MCP server.

The result is one agent experience across Office without forcing Excel to automate the other applications.

Current vertical slice

Browse the public ACP Registry from the Office task pane.
Install Windows binary and npx agent distributions. Ribbon provisions a private Node.js LTS runtime when needed and verifies the official Node archive checksum.
Launch ACP v1 agents, authenticate them, create sessions, and render message chunks, plans, thoughts, and tool progress inline while a turn runs.
Persist theme-independent conversation transcripts with generated titles, agent/model metadata, document binding, New chat, history browsing, and deletion. Ribbon restores native agent context through capability-gated ACP session/resume or session/load; unavailable and cross-document conversations remain safely reviewable.
Gate every destructive Office MCP tool in Ribbon as well as relaying ACP permission requests, with an option to remember an approval for that action during the active agent session. A per-session Auto-approve toggle in the task pane lets you pre-authorize document changes and agent requests for one session; it is off by default, resets to Ask on new conversations or restart, and logs every auto-approved action in the transcript.
Capture a local document checkpoint before each prompt and restore an earlier turn from the task pane; Ribbon saves a safety checkpoint first and restarts the agent session after restore.
Populate an agent-driven model selector from ACP session configuration options and keep it synchronized when the agent changes configuration.
Give every agent a local stdio MCP server named ribbon-office.
Compose MCP guidance from the tools currently connected to that agent session, with the launching Office host's workflow first.
Route MCP calls over a current-user named pipe to every connected Office host.
Use a shared host-branded task pane: Ribbon Grid for Excel, Ribbon Quill for Word, and Ribbon Deck for PowerPoint.
Reopen a closed task pane from the Ribbon group on the Office Home tab.
Match the Windows/Office light or dark appearance with a shared DPI-aware visual system.

Included Office tools:

Host	Tools
Excel	context, list sheets, read/write values and formulas, clear/format ranges, add sheets, create tables and charts
Word	context, bounded reads, headings, text edits, find/replace, formatting, lists, tables, comments, page breaks
PowerPoint	context, structured slide reads, slide lifecycle, text and shapes, formatting, images, tables, charts, notes, backgrounds, find/replace

Excel agent tools

The Excel adapter exposes task-oriented tools rather than a thin mirror of the COM object model:

Tool	Purpose
`excel_get_context`	Resolve the active workbook, sheet, cell, selection, and used range.
`excel_list_sheets`	List worksheet names, visibility, and used ranges.
`excel_read_range`	Read bounded values, formulas, and optional number formats.
`excel_write_range`	Write a rectangular matrix of values. Formula-like strings remain literal.
`excel_write_formulas`	Write a rectangular matrix of explicit A1-style formulas.
`excel_clear_range`	Clear contents, formats, or the complete range state.
`excel_format_range`	Patch fonts, fills, number formats, alignment, borders, dimensions, and AutoFit.
`excel_add_sheet`	Add a validated worksheet at a deliberate workbook position.
`excel_create_table`	Turn an existing data range into a named, styled Excel table.
`excel_create_chart`	Create and position an embedded chart from an inspected source range.

Range reads default to 20,000 cells and are hard-limited to 100,000 cells per call. Writes have the same 100,000-cell hard limit. This keeps agent context bounded and encourages targeted inspection.

Word agent tools

Word operations use document character positions so an agent can inspect structure, make a targeted change, and verify the result:

Tool	Purpose
`word_get_context`	Inspect the active document, selection, story, and document statistics.
`word_read_document`	Read a bounded slice of the main document story.
`word_list_headings`	Discover headings with outline levels and character positions.
`word_replace_selection`	Replace the current selection, including deletion with empty text.
`word_append_text`	Append text before the document's final paragraph mark.
`word_insert_text`	Insert text around the selection or at document boundaries.
`word_replace_range`	Replace or delete an exact span using inspected character positions.
`word_find_replace`	Perform bounded literal replacement with matching options.
`word_format_range`	Patch styles, fonts, paragraph layout, and highlighting.
`word_insert_heading`	Insert a paragraph using a built-in Heading 1–9 style.
`word_insert_list`	Insert structured bulleted or numbered items.
`word_insert_table`	Insert and populate a styled table from a rectangular matrix.
`word_add_comment`	Attach a review comment to the selection or explicit positions.
`word_insert_page_break`	Insert a page break at a deliberate document position.

Document reads are limited to 200,000 characters per call. Character positions are snapshots: agents should refresh context or headings after mutations before making another position-based change.

PowerPoint agent tools

Deck exposes presentation tasks and structured slide state instead of arbitrary COM dispatch:

Capability	Tools
Inspect	`powerpoint_get_context`, `powerpoint_list_slides`, `powerpoint_read_slide`
Slide lifecycle	`powerpoint_add_slide`, `powerpoint_duplicate_slide`, `powerpoint_move_slide`, `powerpoint_delete_slide`
Text and diagrams	`powerpoint_set_slide_title`, `powerpoint_add_textbox`, `powerpoint_add_shape`, `powerpoint_format_shape`, `powerpoint_delete_shape`
Data and media	`powerpoint_add_table`, `powerpoint_add_chart`, `powerpoint_add_image`
Presentation details	`powerpoint_set_speaker_notes`, `powerpoint_set_slide_background`, `powerpoint_find_replace`

PowerPoint coordinates and dimensions are measured in points. Use one-based slide numbers from a recent context/list result and target shapes by the returned shape_name. Shape formatting is patch-based, so omitted properties are preserved. Local images must already exist at an absolute path; Deck does not perform downloads inside PowerPoint.

Architecture

flowchart LR
    E["Excel VSTO"] -->|"current-user pipe"| B["Ribbon Broker"]
    W["Word VSTO"] -->|"current-user pipe"| B
    P["PowerPoint VSTO"] -->|"current-user pipe"| B
    B -->|"ACP over stdio"| A["Installed ACP agent"]
    A -->|"MCP over stdio"| M["Ribbon Office MCP proxy"]
    M -->|"current-user pipe"| B
    B --> R["ACP Registry"]

The add-ins contain only UI and application-specific COM operations. The .NET 10 broker owns everything process-oriented, including agent installation and ACP/MCP transport. See docs/architecture.md for protocol and security details.

Build

Requirements:

Windows with desktop Excel, Word, and PowerPoint
Visual Studio with Office/SharePoint development tools
.NET Framework 4.8 targeting pack
.NET 10 runtime for the broker
Inno Setup 7 to compile the per-user installer

Build the complete solution from a Visual Studio developer shell:

msbuild Ribbon.slnx /t:Build /p:Configuration=Debug /m

The VSTO builds include Ribbon.Broker.exe and its runtime files in each deployment manifest. An installed copy prefers %LOCALAPPDATA%\Ribbon\Broker\Ribbon.Broker.exe. During repository development the shared client can also locate the broker under Ribbon.Broker/bin; RIBBON_BROKER_PATH overrides this lookup.

Signed GitHub Releases are created from semantic-version tags such as v1.2.0 when the tagged commit belongs to main. End users should run Ribbon-Setup-vVERSION.exe from the release. See docs/releasing.md for signing-secret setup, the Inno Setup package, artifact contents, and the Microsoft Marketplace distribution constraint for VSTO add-ins.

To try Ribbon, set Grid, Quill, or Deck as the startup project and press F5. In the corresponding host-branded Ribbon task pane:

Select Agents.
Install a compatible agent such as OpenCode or Codex.
Select it from the agent list and enter a prompt. Use Ctrl+Enter to send.

Agent state is stored under %LOCALAPPDATA%\Ribbon:

agents — downloaded binary agents
runtimes — Ribbon-managed runtimes such as Node.js
sessions — isolated ACP working directories and Office guidance
Conversations — persistent Ribbon-owned transcript and session metadata, limited to the newest 200 conversations
Checkpoints — temporary per-host snapshots used by active task panes; removed when that Office host shuts down
cache — cached ACP Registry document
logs — broker diagnostics

Project layout

Ribbon.Contracts — versioned broker wire contracts shared by .NET Framework and .NET 10
Ribbon.Broker — ACP client, registry installer, session manager, Office MCP proxy, and host router
Ribbon.Vsto — reusable named-pipe client, agent manager, permission UI, and task pane
Grid — Excel host adapter
Quill — Word host adapter
Deck — PowerPoint host adapter

Scope and next work

This is a working architectural slice. The next useful increments are tracked-changes and image/section support for Word, conditional formatting and sorting for Excel, a selectable authentication-method dialog, Authenticode-signing the setup executable with a trusted publisher certificate, and automated integration tests with a fake ACP agent.