Split changelog into separate file

CHANGELOG.md

@@ -0,0 +1,17 @@
+# CHANGELOG
+
+This file records dated repository-level documentation and implementation changes. Keep entries short, factual, and ordered newest last.
+
+## Use
+
+- Record meaningful repo changes here after they are made.
+- Keep implementation details brief and point to the affected files when useful.
+- Do not use this file for task planning; use [`TODO.md`](./TODO.md) for the live work queue.
+- Do not use this file for durable assumptions or guardrails; use [`MEMORY.md`](./MEMORY.md) for that context.
+
+## Entries
+
+- `2026-03-28`: Created `README.md` and `MEMORY.md` from the `/docs` PDFs and current MATLAB code. Confirmed the repo is still an incomplete assignment skeleton with unresolved placeholders and a missing `getRho.m`.
+- `2026-03-28`: Documented professor guidance that the atmosphere model must be integrated into the simulation, must include the stratosphere branch for altitude `> 11 km`, and will not run until the `XX` placeholders are replaced.
+- `2026-03-28`: Clarified file roles so `MEMORY.md` is the durable handoff and `TODO.md` is the active execution tracker.
+- `2026-03-28`: Confirmed the stratosphere equations from `docs/Addendum to Atomosphere Model Feb 26.pdf` and recorded the required `z > 11000 m` branch for the future `getRho.m` implementation.

MEMORY.md

@@ -6,7 +6,8 @@ This file is the durable handoff for AI agents working in this repository. Keep
 
 - `MEMORY.md` stores durable project context: guardrails, sourced facts, assumptions, decisions, code status, and verification notes.
 - `TODO.md` stores the active execution queue and the current critical path.
-- Do not turn `TODO.md` into a second memory file or turn `MEMORY.md` into a running checklist.
+- `CHANGELOG.md` stores dated repository-level change history.
+- Do not turn `TODO.md` into a second memory file, `MEMORY.md` into a running checklist, or `CHANGELOG.md` into a design document.
 
 ## Guardrails
 
@@ -18,6 +19,7 @@ This file is the durable handoff for AI agents working in this repository. Keep
 - Do not describe the model as runnable until all `XX` placeholders are replaced and `getRho.m` exists.
 - Record every meaningful assumption, extracted constant, unresolved issue, and verification result here.
 - Keep `TODO.md` aligned with the current critical path, but keep durable context and decisions in this file.
+- Keep dated repo history in `CHANGELOG.md`, not in this file.
 - Use exact dates in status notes.
 - Do not store secrets, tokens, or personal data in this file.
 
@@ -79,11 +81,4 @@ After any meaningful change, update:
 - `Code Status` if files were added, edited, or made runnable.
 - `Next Actions` only if the durable sequencing changed in a meaningful way.
 - `TODO.md` if the active work queue or current critical path changed.
-- `Change Log` with a short dated note.
+- `CHANGELOG.md` with a short dated note for repo-level changes.
-
-## Change Log
-
-- `2026-03-28`: Created `README.md` and `MEMORY.md` from the `/docs` PDFs and current MATLAB code. Confirmed the repo is still an incomplete assignment skeleton with unresolved placeholders and a missing `getRho.m`.
-- `2026-03-28`: Documented professor guidance that the atmosphere model must be integrated into the simulation, must include the stratosphere branch for altitude `> 11 km`, and will not run until the `XX` placeholders are replaced.
-- `2026-03-28`: Clarified file roles so `MEMORY.md` is the durable handoff and `TODO.md` is the active execution tracker.
-- `2026-03-28`: Confirmed the stratosphere equations from `docs/Addendum to Atomosphere Model Feb 26.pdf` and recorded the required `z > 11000 m` branch for the future `getRho.m` implementation.

README.md

@@ -59,7 +59,8 @@ At the moment, the repository is a partially completed assignment skeleton rathe
 - Treat `/docs` and direct instructor clarifications as authoritative for assignment requirements and parameter values.
 - Record assumptions, extracted tables, unresolved issues, and verification status in [`MEMORY.md`](./MEMORY.md).
 - Track the active execution queue in [`TODO.md`](./TODO.md).
+- Record dated repository-level changes in [`CHANGELOG.md`](./CHANGELOG.md).
 
 ## For AI Agents
 
-Read [`MEMORY.md`](./MEMORY.md) before making changes. Use [`MEMORY.md`](./MEMORY.md) for durable handoff context and [`TODO.md`](./TODO.md) for the live task queue, and update the one that changed so the next agent can continue without re-discovering context.
+Read [`MEMORY.md`](./MEMORY.md) before making changes. Use [`MEMORY.md`](./MEMORY.md) for durable handoff context, [`TODO.md`](./TODO.md) for the live task queue, and [`CHANGELOG.md`](./CHANGELOG.md) for dated repo history, and update the file whose role changed so the next agent can continue without re-discovering context.