Your AI assistant reads your documents, anonymised on your machine and checked by you.

Three things you need

• Tacitum, up to date, on this machine. The free trial is enough to try the AI Connector: its 10 conversions also work with the assistant. To keep using it afterwards, the AI Connector adds to a Tacitum licence (€79, one-time payment). If "AI Connector…" does not appear in Tacitum's left column, your version predates the AI Connector: install the update offered at launch.
• Claude Desktop (Claude's desktop app, by Anthropic) or Codex Desktop (Codex's desktop app, by OpenAI), for Windows, installed and signed in to your account. These are the two supported assistants; you can plug in both.
• The AI Connector: nothing to buy during the free trial. After that, €69 for one year (no VAT applicable, art. 293 B CGI), bought directly from Tacitum (step 1 below), or included in the Tacitum + AI Connector bundle (€148) when you buy the licence on the website. No subscription: when it ends, nothing is charged; you decide whether or not to extend.

Open the "AI Connector" window

In Tacitum, click AI Connector… in the left column. The window recalls how it works and shows the status of your access. Until you have bought it, it offers "Get the AI Connector…".

Buy one year of access

Click "Get the AI Connector…". Tacitum shows the offer, loaded from the licence server: €69 (no VAT applicable, art. 293 B CGI) for one year, with the end date, one year after payment (see the terms of sale, article 8). The invoice is sent to your licence's e-mail address; you can enter another one, which then becomes your licence's contact address.

Tick the box by which you request immediate access and acknowledge that you lose your right of withdrawal (terms of sale, article 8), then click "Pay online": secure payment opens in your browser (Mollie: no bank details go through Tacitum). Leave the Tacitum window open: it updates by itself as soon as the payment is confirmed. If you closed it or confirmation is slow to arrive, click Refresh.

Check: "active until…"

Back in Tacitum, the window shows "AI Connector active until …" in green. If you extended from the link in the e-mail, or if the status has not refreshed, click Refresh: Tacitum queries the licence server with the same data as the licence check (the key and the technical fingerprint of your Windows session), never a document.

"Connect Tacitum to Claude…"

Tacitum creates the extension for Claude Desktop, the file Tacitum.mcpb, saved in Documents\Tacitum. Two cases, depending on your Claude Desktop installation:

• Claude Desktop opens straight onto its extension installation window: confirm.
• Otherwise, Windows File Explorer opens with the Tacitum.mcpb file selected. In Claude Desktop, open Settings → Extensions and drag the file into the drop zone for .MCPB or .DXT files.

Confirm the installation

Claude shows the "Tacitum" extension card with its tools, and a red warning: the extension will have access to your computer, and the information about its developer has not been verified by Anthropic. That is the message shown for an extension installed from a file, outside Anthropic's directory. Tacitum has just created this file on your machine; the program it contains (TacitumMCP.exe) is signed by Tacitum's publisher. Click Install.

"Tacitum" then appears in Settings → Extensions, among the extensions installed on your computer. Depending on your Claude Desktop version, the + menu of the input box also offers the Tacitum shortcuts, whose names are in French: "Analyser un document anonymisé" (analyse an anonymised document), "Ajouter un texte anonymisé" (add an anonymised text), "Relire la réponse en clair" (read the answer back in clear), "Relire et corriger un document Word" (review and correct a Word document), "Rédiger un document Word en clair" (write a Word document in clear).

"Connect Tacitum to Codex…"

Tacitum creates the Tacitum plugin package for Codex, the file Tacitum-Codex.zip, saved in Documents\Tacitum and shown in File Explorer. Then:

1. Extract it completely (right-click → "Extract All…").
2. In the extracted folder, double-click Installer.cmd: the plugin is added to your personal Codex plugin catalogue. Nothing else is changed in Codex.
3. Restart Codex Desktop.
4. In Codex, open the Customize panel ("Personnaliser" in the French interface), then Plugins, Personal tab: "Tacitum" ("Documents protégés localement", locally protected documents) appears under "Created by you". Click + to install it.

Approve Tacitum's guards

On your first exchange, Codex asks you to review the hooks of the plugin: these are Tacitum's three guards, which remind Codex to go through Tacitum for any document and stop its own tools from reading a raw file directly. Allow the selected items (or allow them all). Until they are approved, these protections are not active.

In the Codex input box, the Tacitum tag appears; the plugin also suggests the prompt "Analyse mon document avec Tacitum" (analyse my document with Tacitum).

Ask the assistant, naming Tacitum

In a Claude Desktop or Codex Desktop conversation, phrase your request so that it says the document must go through Tacitum. Do not attach the file to the conversation: Tacitum is the one that reads it, on your machine.

The assistant calls Tacitum, which opens its file picker in the foreground (one or more documents) or, if you asked for a folder, its folder picker (subfolders included, up to 30 documents). Formats: .docx, .pdf, .xlsx / .xlsm, .pptx, .txt, .csv, as well as scans and images (.png, .jpg, .tif, .bmp, .webp, read by text recognition).

Check the masked data

Tacitum analyses the document on your machine. The engine loads with each request, in the background as soon as the picker opens: allow around twenty to thirty seconds after you make your choice (less if you took your time choosing, more on a modest machine, for a scan or for a whole folder). Then the review window you already know opens, with a banner reminding you that the assistant is waiting for this document. You can keep a value detected by mistake, mask a term that was missed, or leave a category in clear (dates, for example, are often useful for the analysis).

For a folder, all the documents are analysed together: the same person or company carries the same code in every document, which lets the assistant cross-check them. You review each document ("Confirm and next file") or, if you prefer, you choose "Anonymize all without review": the remaining documents are then processed with your category choices. Nothing leaves before the end of the batch. Cancelling means no document is sent.

Read what the assistant will receive, then send

Each confirmed document is written to Documents\Tacitum\Anonymisés. After the last confirmation, Tacitum reads them back exactly as written and runs them through a safety net (a value masked in one document is masked in all of them). A final screen shows you, document by document, the exact text that will be sent, with the number of masked items per category. Document titles are anonymised too (the original file name goes through the engine) and can be renamed with a double-click.

Only the "Confirm and send to Claude" button (or "… to Codex") sends anything. If you would rather skip this screen in future, a checkbox turns it off; to get it back, remove the mcp_apercu_envoi key from Tacitum's config.json file, in %APPDATA%\Tacitum.

The assistant answers, with the labels

The assistant receives the anonymised texts and works on them as usual: it refers to people and companies by their codes, which stay consistent from one document to the next. If your review takes a while, it waits and picks up again on its own: you have nothing to restart.

"Show me your answer in clear with Tacitum"

Ask the assistant to show its answer in clear: Tacitum opens a local window where your real values are put back, in red, in place of the codes. This window stays open until you close it and collects the assistant's following answers (history on the left). You can show the labelled version as the assistant wrote it, copy the text, or save it as Word with "Save as Word…", without going back through the AI.

What appears here never goes back to the assistant: Tacitum only tells it how many values were put back.

Never attach the raw document to the conversation

If you drop a file straight into Claude Desktop or Codex Desktop, it goes to the assistant's publisher before Tacitum can step in: no extension can intercept a chat attachment. Get into the habit of naming Tacitum in your request ("with Tacitum") or of using the assistant's Tacitum shortcuts; Tacitum then opens its own file picker. With Codex, the plugin's guards also stop its tools from reading a raw file directly; they do not cover an attachment or text pasted into the conversation.

Good to know

• Two supported assistants: Claude Desktop and Codex Desktop, for Windows. The extension and the plugin are generated for your Tacitum installation; if you move or reinstall Tacitum, run "Connect Tacitum to…" again.
• Only one pending request at a time: review, secure input or Word revision. Finish (or cancel) the current operation before making a new request.
• 30 documents per request at most for a folder; beyond that, choose a subfolder. Old .doc files are not supported by the connector (convert them to .docx, or go through the app).
• A Word revision covers at most 60 corrections per request.
• Scans are read by text recognition: the transcription is flagged as such to the assistant, and a hard-to-read scan is explicitly marked. Review them carefully at the review step.
• Reading back in clear depends on the local mapping: once it is purged (period chosen in Settings), a code can no longer be restored. Save as Word whatever you want to keep.
• Tacitum is an aid, not a guarantee: no automated tool detects 100% of the personal data in a document. That is what the review step is for; you have the final say, including on the categories you choose to leave in clear.