diff --git a/docs/tasks/task-100-task-number-audit/README.md b/docs/tasks/task-100-task-number-audit/README.md
new file mode 100644
index 0000000..6310170
--- /dev/null
+++ b/docs/tasks/task-100-task-number-audit/README.md
@@ -0,0 +1,64 @@
+---
+task_number: 100
+status: open
+priority: P4
+owner: Michael
+created: 2026-04-08
+---
+
+# Task #100: Task Number Audit & Standardization
+
+**Created:** April 8, 2026  
+**Created By:** Chronicler #69 (The Surveyor)  
+**Priority:** P4 (Low - Address when issues arise)  
+**Status:** Open  
+
+---
+
+## Overview
+
+During the mobile task index implementation, we discovered that many legacy tasks never had official task numbers assigned. We added `task_number:` to YAML frontmatter for 26 tasks that had documented numbers, but ~30 tasks remain unnumbered.
+
+## Current State
+
+- **57 total task folders** in `docs/tasks/`
+- **26 tasks** have `task_number:` in frontmatter
+- **~31 tasks** are unnumbered legacy tasks
+
+## When To Address
+
+Monitor for issues:
+- New tasks should ALWAYS include `task_number:` in frontmatter
+- If unnumbered tasks cause confusion, batch-assign numbers
+- If mobile task index sorting is problematic, prioritize this task
+
+## Standard for New Tasks
+
+All new tasks MUST include in frontmatter:
+```yaml
+---
+task_number: XXX
+status: open | blocked | complete
+priority: P1 | P2 | P3 | P4
+owner: Michael | Meg | Holly
+created: YYYY-MM-DD
+---
+```
+
+## Next Available Task Number
+
+Check highest existing number before creating new tasks:
+```bash
+grep -rh "^task_number:" docs/tasks/ | sort -t: -k2 -n | tail -1
+```
+
+As of April 8, 2026: **Next available = #101**
+
+## Archive Threshold
+
+Per FFG-STD (established April 8, 2026 by Chronicler #69):
+> **Archive if ≥50KB OR ≥4 files — otherwise delete.**
+
+---
+
+**Fire + Frost + Foundation = Where Love Builds Legacy** 💙🔥❄️