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What makes Veyyon different

These ideas set Veyyon apart. Each is shipped unless noted as Spec — not shipped.

For a reader-first pass, start with the benefit chapters. This page is the compact design map.

Hashline-first editing

Open models emit reliable hashline patches when the harness matches their training. Veyyon’s edit and write tools apply hashline patches with verification before bytes hit disk, so an edit either lands exactly or fails loudly with recovery hints.

See Editing and repair and The hashline edit engine.

Tool approval by tier (autonomy ladder)

tools.approvalMode (plan, ask, auto-edit, yolo; legacy always-ask / write aliases) and per-tool tools.approval overrides gate read, write, and exec tiers. Bash can force prompts on destructive patterns even in permissive modes.

See docs/approval-mode.md and /settings → Advanced → Safety.

Every model in the harness it fits

Model selection is three explicit slots — the interactive model (chosen with /model), the subagent model, and the compaction model (both set in settings). No default model stands in for the others. Optional named roles live in settings, scoped per profile, for anyone who wants specific work types pinned to specific models. Prompts and tool exposure adapt per model and per agent kind (main vs subagent).

Provider-agnostic runtime

The agent loop, TUI, session format, MCP, skills, hooks, and extensions are provider-neutral. You configure providers in ~/.veyyon/agent/config.yml or via /setup / /providers.

Control flow in the harness

Compaction, goal continuation, plan mode, vibe mode, and task subagents are engine features, not persona-only instructions. Goal mode can auto-continue idle sessions toward an objective; plan mode drafts a plan file before mutating the repo.

Spec — not shipped (documented elsewhere)

  • A full schema-based tool-call repair cascade. General schema repair on tool calls is shipped; the broader cascade is planned. See Repair overview.
  • Self-contained profiles that own isolated MCP/skills copies per profile. Today profiles relocate the agent directory to ~/.veyyon/profiles/<name>/agent/.
  • A top-level veyyon doctor install-health command. Use veyyon plugin doctor and /debug today.

Where to go next