docs: clarify Coven as a substrate for harnesses, not a harness itself

content/docs/guide/concepts.mdx

@@ -43,6 +43,8 @@ Use **OpenCoven** when talking about the broader project family.
 
 Coven is the local runtime substrate. It owns project-scoped harness sessions, PTYs, logs, local daemon state, and the socket API.
 
+Coven is **not a harness**. Harnesses — Codex, Claude Code, and future adapters — are external coding-agent CLIs that operate *within* Coven's substrate. Coven provides the shared layer they all run on: enforced project boundaries, supervised PTY lifecycle, append-only session records, and a stable local API that any client can talk to regardless of which harness is running.
+
 Use **Coven** for the CLI, daemon, Rust crate, npm wrapper, and local session runtime.
 
 ## CovenCLI

content/docs/guide/getting-started.mdx

@@ -9,11 +9,20 @@ This guide takes a new user from a fresh checkout or npm install to a visible pr
 
 ## What Coven Is
 
-Coven is a local-first runtime for coding-agent harnesses. It runs supported CLIs such as Codex and Claude Code inside explicit project boundaries, records session metadata and events, and exposes the work through a CLI, TUI, and local socket API.
+Coven is not a harness. It is the **substrate** that harnesses operate within.
+
+A harness — Codex, Claude Code, or any future adapter — brings its own provider credentials, model selection, and tool runtime. Coven provides the shared layer underneath: enforced project boundaries, supervised PTY processes, an append-only session record, and a stable local API. When work passes through Coven, every run gains consistent lifecycle management, replay, and auditability regardless of which harness ran it.
+
+This matters in practice:
+
+- **Provider independence** — switch between Codex and Claude Code without rewiring your workflow; the substrate stays the same.
+- **Enforced boundaries** — harnesses can only operate inside the project root you declared; no harness can silently widen scope.
+- **Auditable history** — every session is recorded and replayable; completed work survives process restarts.
+- **Unified client surface** — any client (CLI, TUI, CastCodes, OpenClaw, or a script) talks to any harness through one local API.
 
 The short promise:
 
-> One project. Any harness. Visible work.
+> One substrate. Any harness. Reproducible, auditable work.
 
 ## Install Paths
 

content/docs/harnesses/what-is-a-harness.mdx

@@ -4,11 +4,14 @@ summary: "A harness is a PTY-driven adapter for one external coding-agent CLI."
 description: "Definition of a Coven harness and the boundary between harnesses, familiars, clients, and the daemon."
 read_when:
   - You are new to Coven terminology
+  - You need to explain why a harness is not the same thing as Coven itself
   - You need to explain why a harness is not the same thing as a familiar
 ---
 
 A harness is a coding-agent CLI that Coven can run as a supervised process. The harness is not the daemon, not a familiar, and not the user interface. It is the external agent runtime that receives a prompt and works inside a PTY.
 
+**Coven is not a harness.** Coven is the substrate that harnesses run within. It provides enforced project boundaries, supervised PTY lifecycle, session records, event logs, and a unified local API — so that any harness can operate in a well-defined, auditable, reproducible way without each one needing to reinvent lifecycle management, boundary enforcement, or client access.
+
 ## Boundary map
 
 | Term | Role |

lib/coven-proxy-dial.ts

@@ -36,7 +36,11 @@ export function envelope(
   details: Record<string, unknown>,
   status: number,
 ): Response {
-  return Response.json({ error: { code, message, details } }, { status });
+  const body = JSON.stringify({ error: { code, message, details } }, null, 2) + '\n';
+  return new Response(body, {
+    status,
+    headers: { 'content-type': 'application/json; charset=utf-8' },
+  });
 }
 
 export function daemonUnreachable(