**Heartbeat:**`_agent/heartbeat/last-session.md` is a one-line pointer file an agent MAY write at session end (`<session-log-path> @ <ISO-timestamp>`). Reading it at session start is cheaper than listing the sessions directory; use it as a hint, not a source of truth — fall back to the directory listing if it's missing or stale.
**Slug rules:** kebab-case, ASCII only, truncate to ~40 chars.
---
## Canonical Frontmatter
Every note starts with this block. Fill what applies; leave the rest empty rather than guessing.
```yaml
---
type:# see Note Types below
status:# active | draft | done | archived | complete
created:# YYYY-MM-DD (or YYYY-MM-DDTHH:mm for sessions)
updated:# YYYY-MM-DD
tags:[]
agent_written:false
source_notes:[]# plain relative paths as strings — NEVER [[wikilinks]]
---
```
`agent_written: true` + a populated `source_notes` is the key signal separating
agent-managed content from human-authored content. When appending with POST, do
not rewrite frontmatter — the append goes after existing content. To change
`updated:` or `status:`, use PATCH with `Target-Type: frontmatter`.
**Frontmatter field semantics:**
-`created:` is the **earliest known date** the entity was tracked in the vault — *not* "today". When merging notes (e.g. promoting an `on-hold/` project into `active/`), preserve the earliest `created:` from any merged source and only update `updated:`.
-`source_notes` is a **backward link** — the note(s) that triggered or supplied content for this one (e.g. the session log a project update came from). Forward links go in the `## Related` body section, never here.
-`status:` for a project MUST match its folder under `projects/` (`active`, `incubating`, `on-hold`, `archived`). Moving the file and updating `status:` are the same operation.
> **No `[[wikilinks]]` in frontmatter.** YAML parses `[[...]]` as nested lists, so wiki
> links there break and never render as clickable links in reading view. Put all
> cross-references in a **`## Related`** section in the note **body** (bulleted `[[links]]`).
-`## Fact / Pattern` — **promoted, deduped rules.** No date prefix. Timeless.
-`## Observations` — **timestamped raw observations.** Date-prefixed lines (`- 2026-06-06: ...`). Default landing zone for new evidence.
-`## Evidence` — citations/links supporting the rules
-`## Recommendation or Implication` — how the rules should shape behavior
-`## Review Notes` — confidence / last review date
Append observed facts under `## Observations` by default. Promote to `## Fact / Pattern` (dropping the date) once a pattern stabilizes. "The operator" is Jason — he is both operator and architect of this vault.
See `session-log-template.md`. ECHO uses an **HHMM time component** in the filename — this is **canonical, not optional**. The four-digit local-time component makes filenames lex-sort in true chronological order, which the loading procedure relies on. Older session logs without HHMM exist; leave them alone, but every new one must use the full `YYYY-MM-DD-HHMM-<slug>.md` form.
ADR-style: Context → Decision → Consequences. If the decision belongs to an existing project, PATCH-append the wikilink into that project's `## Decisions` heading. Don't use `decisions/by-project/` — it's legacy scaffolding that's intentionally left empty.
