move avatar-PNG helpers to hive-core, configurable org avatar

core_avatar_png() and config_org_avatar_png() were hive-sh4re
functions used only by hive-c0re::forge::users. Move them there as
private path-resolution helpers (core_avatar_png_path,
config_org_avatar_png_path), following the existing
std::env::var(...).expect(...) required-env-var style used elsewhere
in hive-c0re.

The org avatar is now independently configurable:
services.hyperhive.c0re.orgAvatarPng (nullable path, default null)
lets an operator override just the agent-configs org avatar PNG
without replacing the whole assets package. Wired via a new
HIVE_ORG_AVATAR_PNG env var that falls back to the bundled PNG when
the option is unset. The core avatar stays under HIVE_ASSETS_DIR,
unchanged.

hive-c0re/src/forge/users.rs

@@ -24,11 +24,36 @@ use crate::paths::FORGE_CORE_TOKEN as CORE_TOKEN_PATH;
 // in `crate::paths` — one-shot guards: the upload/align runs once, the
 // marker is written, subsequent startups skip. Delete one to force its
 // step to re-run.
-// Avatar PNGs are loaded at runtime from
-// `$HIVE_ASSETS_DIR/branding/{hyperhive,agent-configs}.png` via the
-// helpers in `hive_sh4re::assets`. The `agent-configs.png` is
-// rendered from its SVG during the `hyperhive-assets` derivation's
-// build.
+// Avatar PNG paths are resolved by `core_avatar_png_path` /
+// `config_org_avatar_png_path` below — only-used-here, so they live
+// in this module rather than the shared `hive_sh4re::assets` helpers
+// (which stay for paths every crate needs, e.g. `branding_svg`).
+
+/// `$HIVE_ASSETS_DIR/branding/hyperhive.png` — the core mark,
+/// rasterised. Not independently configurable (unlike the org avatar
+/// below) — override the whole `services.hyperhive.c0re.assets`
+/// package to change it.
+fn core_avatar_png_path() -> std::path::PathBuf {
+    let dir = std::env::var("HIVE_ASSETS_DIR").expect(
+        "HIVE_ASSETS_DIR is unset — hive-c0re.nix sets it unconditionally, \
+         so this process was started outside the NixOS module",
+    );
+    std::path::PathBuf::from(dir).join("branding/hyperhive.png")
+}
+
+/// Path to the `agent-configs` org's avatar PNG. Independently
+/// configurable via `services.hyperhive.c0re.orgAvatarPng` — the nix
+/// module resolves `HIVE_ORG_AVATAR_PNG` to that option's value, or
+/// the bundled `agent-configs.png` from `assets` when unset, so an
+/// operator can override just this image without replacing the whole
+/// `assets` package.
+fn config_org_avatar_png_path() -> std::path::PathBuf {
+    std::path::PathBuf::from(std::env::var("HIVE_ORG_AVATAR_PNG").expect(
+        "HIVE_ORG_AVATAR_PNG is unset — hive-c0re.nix sets it unconditionally \
+         (from services.hyperhive.c0re.orgAvatarPng or the bundled default), \
+         so this process was started outside the NixOS module",
+    ))
+}
 /// Per-agent token scopes (broad-but-not-admin) for tokens hive-c0re
 /// mints itself on the **internal** forge. See `docs/forge.md::Token
 /// scopes` for the per-scope rationale. Not `pub(super)` — external
@@ -400,7 +425,7 @@ pub(super) async fn ensure_core_avatar(token: &str) -> Result<()> {
     if marker.exists() {
         return Ok(());
     }
-    let png_path = hive_sh4re::assets::core_avatar_png();
+    let png_path = core_avatar_png_path();
     let png_bytes = tokio::fs::read(&png_path)
         .await
         .with_context(|| format!("read core avatar PNG from {}", png_path.display()))?;
@@ -432,7 +457,7 @@ pub(super) async fn ensure_config_org_avatar(token: &str) -> Result<()> {
     if marker.exists() {
         return Ok(());
     }
-    let png_path = hive_sh4re::assets::config_org_avatar_png();
+    let png_path = config_org_avatar_png_path();
     let png_bytes = tokio::fs::read(&png_path)
         .await
         .with_context(|| format!("read {CONFIG_ORG} avatar PNG from {}", png_path.display()))?;

hive-sh4re/src/assets.rs

@@ -50,23 +50,6 @@ pub fn branding_svg() -> PathBuf {
     dir().join("branding/hyperhive.svg")
 }
 
-/// `$HIVE_ASSETS_DIR/branding/hyperhive.png` — the same mark
-/// rasterised, used by `hive-c0re::forge::push_avatar` to upload
-/// the forge org avatar.
-#[must_use]
-pub fn core_avatar_png() -> PathBuf {
-    dir().join("branding/hyperhive.png")
-}
-
-/// `$HIVE_ASSETS_DIR/branding/agent-configs.png` — secondary org
-/// mark for the `agent-configs/` mirror org. Rendered from
-/// `agent-configs.svg` at asset-build time (was rendered in
-/// `hive-c0re/build.rs`).
-#[must_use]
-pub fn config_org_avatar_png() -> PathBuf {
-    dir().join("branding/agent-configs.png")
-}
-
 /// `$HIVE_ASSETS_DIR/prompts/system.md` — the claude system prompt
 /// template. `hive-agent::prompt::render` filters the role markers
 /// inside it per agent / manager flavor.

nix/host-modules/hive-c0re/environment.nix

@@ -39,8 +39,17 @@ in
   HIVE_AGENT_FRONTEND_DIR = "${cfg.servedFrontend}/agent";
   # Path to the static runtime asset tree (branding + claude
   # prompts). `hive_sh4re::assets::*` reads paths underneath.
-  # `forge.rs` reads the avatar PNGs from here on startup.
+  # `forge/users.rs` reads the core avatar PNG from here on startup.
   HIVE_ASSETS_DIR = "${cfg.assets}/share/hyperhive";
+  # `agent-configs` org avatar PNG — independently overridable via
+  # `orgAvatarPng` without replacing the whole `assets` package.
+  # Falls back to the bundled PNG under HIVE_ASSETS_DIR when unset.
+  # Read by `forge::users::config_org_avatar_png_path`.
+  HIVE_ORG_AVATAR_PNG =
+    if cfg.orgAvatarPng != null then
+      "${cfg.orgAvatarPng}"
+    else
+      "${cfg.assets}/share/hyperhive/branding/agent-configs.png";
   # Whether this hive runs ruthless — no root/manager agent at all
   # (`auto_update::ensure_root_agent`). Default false = root
   # auto-managed; true makes the sweep a no-op.

nix/host-modules/hive-c0re/options.nix

@@ -55,6 +55,19 @@
         rust derivation.
       '';
     };
+    orgAvatarPng = lib.mkOption {
+      type = lib.types.nullOr lib.types.path;
+      default = null;
+      description = ''
+        PNG uploaded once as the `agent-configs` Forgejo org's avatar
+        (`forge::users::ensure_config_org_avatar`, one-shot,
+        marker-guarded — delete `forge/agent-configs-avatar-set` under
+        the state dir to force a re-upload after changing this).
+        Defaults (`null`) to the bundled `agent-configs.png` from
+        `assets`. Set this to override just the org avatar without
+        replacing the whole `assets` package.
+      '';
+    };
     xdgIcons = lib.mkOption {
       type = lib.types.package;
       defaultText = lib.literalExpression "hyperhive.packages.\${system}.xdg-icons";