# Milestone Write-up — M<N>: <milestone name>

> Copy this file per milestone (e.g. `MILESTONE-M3.md`) and fill it in. The
> flavor line below is required **every** milestone, not just the first.

## Flavor

(contacts book | gradebook | expense tracker) — same flavor for every milestone

## AI used

(none | Tier 2) — see `AGENTS.md` for what Tier 2 permits

## What I built

Which common-interface functions are now implemented, in my own words
(e.g. "`list_append`/`list_find`/`list_remove` over a singly linked list, with
`list_free` walking and freeing every node and record"). Name the files.

## Verification evidence

Paste the output of the gates for this milestone — and the CI report link from
Forgejo Actions:

```text
make
make test
make sanitize     # ASan/UBSan (M5+)
make valgrind     # 0 bytes lost (M5)
```

## Pre-tool prediction

Before running the tool/CI: what did you predict would happen, and which test
did you expect to fail? (If nothing failed — say what made you confident.)

## Student-authored challenge case

A test or scenario **you** wrote that the starter didn't cover (e.g. remove the
head node, a 10k-record list, empty fields in save/load). What does it check
and why does it matter?

## Novel transfer

A new use of what you built this milestone — apply the linked list / buffer /
store to a different domain (e.g. "if the record were a todo item instead of a
contact…") and sketch how your code would change.

## Reflection

What broke, what you learned, what you'd do differently next milestone.