docs: cover new contextInjection 'never' mode and Nix daemon PATH support

Two recent code changes lacked or had only partial doc coverage:

- contextInjection 'never' (#65006, xDarkicex): the new mode is now
  documented under agents.defaults.contextInjection, alongside the
  existing 'continuation-skip' mode, with guidance on when to use it
  (custom context engines, native runtimes that own their prompt).
- Nix Home Manager daemon PATH (#44402, jerome.benoit): document the
  service PATH auto-discovery (NIX_PROFILES right-to-left precedence
  and ~/.nix-profile/bin fallback) under the Nix install page.

Also sentence-case three Title-Cased headings on the Nix page ('What
You Get', 'Quick Start', 'Nix Mode Runtime Behavior') and drop a
duplicate body H1 that restated the frontmatter title.

docs/gateway/config-agents.md

@@ -72,6 +72,7 @@ Disables automatic creation of workspace bootstrap files (`AGENTS.md`, `SOUL.md`
 Controls when workspace bootstrap files are injected into the system prompt. Default: `"always"`.
 
 - `"continuation-skip"`: safe continuation turns (after a completed assistant response) skip workspace bootstrap re-injection, reducing prompt size. Heartbeat runs and post-compaction retries still rebuild context.
+- `"never"`: disable workspace bootstrap and context-file injection on every turn. Use this only for agents that fully own their prompt lifecycle (custom context engines, native runtimes that build their own context, or specialized bootstrap-free workflows). Heartbeat and compaction-recovery turns also skip injection.
 
 ```json5
 {

docs/install/nix.md

@@ -7,22 +7,20 @@ read_when:
 title: "Nix"
 ---
 
-# Nix Installation
-
-Install OpenClaw declaratively with **[nix-openclaw](https://github.com/openclaw/nix-openclaw)** -- a batteries-included Home Manager module.
+Install OpenClaw declaratively with **[nix-openclaw](https://github.com/openclaw/nix-openclaw)** — a batteries-included Home Manager module.
 
 <Info>
 The [nix-openclaw](https://github.com/openclaw/nix-openclaw) repo is the source of truth for Nix installation. This page is a quick overview.
 </Info>
 
-## What You Get
+## What you get
 
 - Gateway + macOS app + tools (whisper, spotify, cameras) -- all pinned
 - Launchd service that survives reboots
 - Plugin system with declarative config
 - Instant rollback: `home-manager switch --rollback`
 
-## Quick Start
+## Quick start
 
 <Steps>
   <Step title="Install Determinate Nix">
@@ -50,7 +48,7 @@ The [nix-openclaw](https://github.com/openclaw/nix-openclaw) repo is the source
 
 See the [nix-openclaw README](https://github.com/openclaw/nix-openclaw) for full module options and examples.
 
-## Nix Mode Runtime Behavior
+## Nix-mode runtime behavior
 
 When `OPENCLAW_NIX_MODE=1` is set (automatic with nix-openclaw), OpenClaw enters a deterministic mode that disables auto-install flows.
 
@@ -82,6 +80,18 @@ OpenClaw reads JSON5 config from `OPENCLAW_CONFIG_PATH` and stores mutable data
 | `OPENCLAW_STATE_DIR`   | `~/.openclaw`                           |
 | `OPENCLAW_CONFIG_PATH` | `$OPENCLAW_STATE_DIR/openclaw.json`     |
 
+### Service PATH discovery
+
+The launchd/systemd gateway service auto-discovers Nix-profile binaries so
+plugins and tools that shell out to `nix`-installed executables work without
+manual PATH setup:
+
+- When `NIX_PROFILES` is set, every entry is added to the service PATH in
+  right-to-left precedence (matches Nix shell precedence — rightmost wins).
+- When `NIX_PROFILES` is unset, `~/.nix-profile/bin` is added as a fallback.
+
+This applies to both macOS launchd and Linux systemd service environments.
+
 ## Related
 
 - [nix-openclaw](https://github.com/openclaw/nix-openclaw) -- full setup guide