diff --git a/doc/index.md b/doc/index.md
index 0585204..5d0ab1b 100644
--- a/doc/index.md
+++ b/doc/index.md
@@ -1,11 +1,37 @@
 # Documentation
 
 * initiate
+* idea
 * [Bash Tips](./bash_tips.md)
-* [todo](./todo.md)
 
 ## initiate
 
 Rk: useful when timezone has changed or ghostty command has been installed aftwerwards
 
 `miaou-bash --initiate`
+
+## IDEA
+
+### distinguish heredoc over pipe
+
+```bash
+miaou-bash <<EOF
+echo HEREDOC
+EOF
+```
+
+```bash
+miaou-bash < <(echo 'echo PIPE1')
+```
+
+```bash
+echo 'echo PIPE2' | miaou-bash
+```
+
+---
+
+## TODO
+
+* [ ] prompt git shows version with `+` when there is more than one commit over current version. ie: v0.0.0 + 2 commits more should display v-1.0.0+
+* [ ] semver_git_tag should append `RELEASE_NOTES.md` from this TODO markdown file, providing that NEW NOTE section below contains appropriate items to fulfill the current release note
+  * [ ] git log <LATEST_TAG>..HEAD --oneline
diff --git a/doc/todo.md b/doc/todo.md
deleted file mode 100644
index 1220625..0000000
--- a/doc/todo.md
+++ /dev/null
@@ -1,5 +0,0 @@
-# TODO
-
-* [ ] prompt git shows version with `+` when there is more than one commit over current version. ie: v0.0.0 + 2 commits more should display v-1.0.0+
-* [ ] semver_git_tag should append `RELEASE_NOTES.md` from this TODO markdown file, providing that NEW NOTE section below contains appropriate items to fulfill the current release note
-  * [ ] git log <LATEST_TAG>..HEAD --oneline