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tachý wiki

Internal design and data-model reference for tachý. The README covers features, installation, deployment, and usage; this wiki covers how and why it is built the way it is.

tachý is a self-hosted, source-agnostic knowledge engine for engineering work items. It keeps an archive of approved lessons from past tickets and issues and retrieves them when a similar work item comes in. It never calls an LLM on its core path; the agent (Claude Code, Codex CLI, or any MCP client) is the reasoning layer. The one Claude-coupled component is the optional server-side agent behind the web Chat.

Two loops around work items, plus a third way in that skips the ticket entirely:

• Ingest. Analyze a work item, then save an approved lesson. Nothing becomes knowledge until a human approves it.
• Consult. Given a new work item, surface relevant past lessons.
• Load context. Feed in freeform material (a codebase overview, a runbook, an architecture note) with no work item at all, stored as reference docs and searched alongside the lessons.

Pages

• Architecture - the shape of the system and why the core is LLM-agnostic.
• Packages - what lives where.
• Data Model - customer-blind entries, controlled vocabulary, promoted facets, the schema tour.
• Sources - the pluggable source interface, Freshdesk and GitHub.
• Search - hybrid keyword plus semantic retrieval, local embeddings.
• Authentication and Users - setup wizard, auth modes, roles, sessions.
• Runtime Settings - DB-backed non-secret settings and precedence.
• Server-Side Agent - the Claude Agent SDK, the tool allowlist, the approval flow, cost policy.
• MCP Tools - the full tool reference.
• Compliance and Redaction - optional PII and secret scrubbing at the MCP boundary.
• Security Model - the consolidated security posture.
• REST API - endpoint reference.

Frequently asked

Is the SDK only for Claude Code? No. Two integration surfaces exist, and only one is Claude-specific. The MCP server is vendor-neutral: any MCP client (Claude Code, Codex CLI, VS Code Copilot, or an organization's own model) drives it. The server-side agent behind the web Chat uses the Claude Agent SDK, a headless programmatic library (the same engine that powers Claude Code, but not Claude Code itself). That is the only Claude coupling in the project, isolated to one file.