diff --git a/SKILL.md b/SKILL.md
index fa94a46..9413b13 100644
--- a/SKILL.md
+++ b/SKILL.md
@@ -3,21 +3,22 @@ name: superpaper
 description: >-
   Reconstruct a paper's argument thread and write structured Chinese
   lecture notes with a claims/symbols/derivation ledger, then route
-  figures to superfig, supertensor, or (later) superderive. Use when
+  figures to superfig, supertensor, or superderive. Use when
   the user asks for 读论文, 论文笔记, 脉络梳理, 公式推导, 抽象公式图像化,
   arXiv notes, paper notes, or $superpaper. Not for drawing a single
-  architecture figure (use superfig) or a tensor-shape figure (use
-  supertensor) or for turning a lecture video into notes
-  (use youtube-render-pdf / bilibili-render-pdf).
+  architecture figure (use superfig), a tensor-shape figure (use
+  supertensor), a standalone rewrite figure (use superderive), or a
+  lecture video (use youtube-render-pdf / bilibili-render-pdf).
 ---
 
 # superpaper
 
 论文侧的 `youtube-render-pdf`：**编排层**，不是 figure 包。输入一篇论文，输出
 `ledger.yaml` + 结构化中文笔记。图一律委派给子仓库，不要在笔记里
-`\usepackage{superfig}` / `supertensor`。
+`\usepackage{superfig}` / `supertensor` / `superderive`。
 
-本目录是家族母仓库。子仓库在 `superfig/` 与 `supertensor/`。
+本目录是家族母仓库。子仓库在 `superfig/`、`supertensor/`、`superderive/`。
+委派一张图时**先读**对应子目录的 `SKILL.md`，再画。
 契约细节按需加载 `references/`；schema 在 `assets/ledger.schema.yaml`。
 
 ## When to use
@@ -25,9 +26,9 @@ description: >-
 - 读论文、梳理脉络、展开公式推导、把抽象公式变成图。
 - 需要一张以上的图，或需要符号表 / claim 覆盖。
 
-Do **not** use when the user only wants one architecture figure (`superfig`)
-or one tensor-shape figure (`supertensor`), or when the source is a lecture
-video.
+Do **not** use when the user only wants one architecture figure (`superfig`),
+one tensor-shape figure (`supertensor`), or one rewrite figure (`superderive`),
+or when the source is a lecture video.
 
 ## Route figures (do not draw here)
 
@@ -51,7 +52,7 @@ video.
 6. `./scripts/lint.py --work <dir>` 然后 `./scripts/build.sh --work <dir>`。
 7. 改术语或改图：先改 ledger，再改那一处。
 
-Worked trees: `examples/excerpt-toy/`（`align` 推导）、`examples/pipeline-delegate/`、`examples/tensor-delegate/`。
+Worked trees: `examples/excerpt-toy/`（`align`）、`examples/pipeline-delegate/`、`examples/tensor-delegate/`、`examples/derive-delegate/`。
 
 ## Spawn recipe
 
diff --git a/agents/openai.yaml b/agents/openai.yaml
index 187e8be..c3be297 100644
--- a/agents/openai.yaml
+++ b/agents/openai.yaml
@@ -4,5 +4,6 @@ interface:
   default_prompt: >-
     Use $superpaper to reconstruct this paper's argument thread,
     expand the key derivations, and produce structured Chinese notes.
-    Build ledger.yaml first. Route figures to superfig / supertensor / align;
-    do not draw inside superpaper and do not \usepackage{superfig} in the notes.
+    Build ledger.yaml first. Route figures to superfig / supertensor /
+    superderive / align; do not draw inside superpaper and do not
+    \usepackage{superfig|supertensor|superderive} in the notes.
diff --git a/superderive b/superderive
index 9f635d3..45db61f 160000
--- a/superderive
+++ b/superderive
@@ -1 +1 @@
-Subproject commit 9f635d358b694c8bafda960a8d495e96f220cda5
+Subproject commit 45db61f3e2de53bf0c0c990fe709b3a51aa4cdc5
diff --git a/superfig b/superfig
index db5598f..6ed0174 160000
--- a/superfig
+++ b/superfig
@@ -1 +1 @@
-Subproject commit db5598fbf77d284de7ff92a072ca7506e2296407
+Subproject commit 6ed01743cf1cba53a46899ce557bfb7f4c9b7e09
diff --git a/supertensor b/supertensor
index 7d62e02..8ada8e5 160000
--- a/supertensor
+++ b/supertensor
@@ -1 +1 @@
-Subproject commit 7d62e0279a0c19f0af969c4947760fe3649ecec5
+Subproject commit 8ada8e57c5f5989d54667842338f12487f0ab64a