ver 1.5.0 — six-improvement pass: retention, routing, self-firing memory

1. capture-update keeps the whole body (was truncating to first line)
2. frontmatter completeness: kind-default status + kind-seeded tags at
   capture, fm create-or-replace, incomplete-frontmatter lint, sweep
   backfill (one data source: KIND_STATUS/KIND_REQUIRED_FM)
3. pre-write duplicate gate (exit 76, --merge-into/--force)
4. recall corpus + ranking: sessions/journal indexed (down-weighted),
   BM25 x freshness x status fusion, recall --json, index schema 2
5. session hooks: SessionStart auto-load, Stop reflection nudge
6. one-tap triage verb with processing-log audit; --json on read verbs

+22 mock end-to-end tests; all suites green. Docs current (README,
CHANGELOG, SKILL.md, commands, references, MAINTENANCE, eval README).
Drops tracked .DS_Store (gitignored); retires README-gretchen.md
(moved to gitignored dist/); adds the field report that drove item 2.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

echo-memory.plugin.src/skills/echo-memory/references/api-reference.md

@@ -156,6 +156,12 @@ Same call with `Operation: prepend`.
 
 ### Patch a frontmatter field
 
+> A `PATCH` `Target-Type: frontmatter` **replace** on a key the note does not have returns
+> `400 invalid-target` — the raw API cannot create a key. `echo.py fm` (v1.5+) handles this:
+> on that 400 it surgically inserts the one `field: value` line into the frontmatter block
+> and re-PUTs (verified), leaving every other line untouched. Raw-curl users must GET-edit-PUT
+> themselves — carefully (a naive rewrite is how frontmatter gets clobbered).
+
 ```bash
 curl -s -X PATCH \
   -H "Authorization: Bearer $ECHO_KEY" \