Remove ECHO back-compat shims — CHORUS is a clean break

Decision: CHORUS deploys as fresh vaults on new machines for different
users, so no ECHO adoption path is needed. Removed the Phase-1 shims:
- chorus_config: legacy ECHO_* env aliasing and the read-only
  ~/.claude/echo-memory/config.json fallback
- chorus_queue / chorus_hook_stop: ~/.echo-memory state-dir fallback
- load/doctor/bootstrap/vault_lint/sweep/migrate: the _agent/echo-vault.md
  marker dual-probe; routing drops agent-marker-legacy (36 routes)
- .gitignore, README, CHANGELOG, CHORUS-PLAN.md updated (decision #6;
  Phase 3 no longer migrates the live ECHO vault — fresh bootstrap only)

All suites green: 25/25 unit, scaffold, routing-sync, 4 mock e2e,
run_eval metrics unchanged. Rebuilt chorus-memory.plugin.

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

CHORUS-PLAN.md

@@ -57,7 +57,7 @@ on two machines but not for N people.
   its own Obsidian + Local REST API instance exposed there (separate from
   ECHO's `echoapi.alwisp.com`; the personal ECHO vault is untouched). The
   endpoint stays machine-local/baked config, never in source, same as ECHO.
-  `owner` → `group` (with `owner` accepted as a legacy alias). Resolution order
+  `owner` → `group`. Resolution order
   unchanged: baked > env (`CHORUS_MEMBER` etc.) > config file. Baked per-user
   builds (`build.py --bake-key --label alice`) already exist and become the
   primary **onboarding** mechanism: one artifact per member, member id baked in.
@@ -158,10 +158,10 @@ theirs alone). What remains shared-write:
 | Commands | `/echo-{load,save,recall,reflect,triage,sweep,health,doctor}` | `/chorus-*` |
 | Scripts | `echo*.py` (16 modules + imports everywhere) | `chorus*.py` |
 | Exception | `EchoError` | `ChorusError` |
-| Env vars | `ECHO_OWNER/BASE/KEY/CONFIG/TODAY/VERIFY/LOCK_TTL/TIMEOUT/WORKERS/STATE_DIR/CLIENT/DUP_GATE/REFLECT_MIN_TURNS/FRESH_HALF_LIFE` | `CHORUS_*` (+ new `CHORUS_MEMBER`); `ECHO_*` read as fallback aliases in `chorus_config` for one major version |
-| Config file | `~/.claude/echo-memory/config.json` | `~/.claude/chorus-memory/config.json` (import path: `config import` accepts an old echo config) |
+| Env vars | `ECHO_OWNER/BASE/KEY/CONFIG/TODAY/VERIFY/LOCK_TTL/TIMEOUT/WORKERS/STATE_DIR/CLIENT/DUP_GATE/REFLECT_MIN_TURNS/FRESH_HALF_LIFE` | `CHORUS_*` (+ new `CHORUS_MEMBER`) |
+| Config file | `~/.claude/echo-memory/config.json` | `~/.claude/chorus-memory/config.json` |
 | State dir | `~/.echo-memory/` | `~/.chorus-memory/` |
-| Marker | `_agent/echo-vault.md` (hardcoded in 8 files + routing.json) | `_agent/chorus-vault.md`; probe checks new name **then** old (adoption path) |
+| Marker | `_agent/echo-vault.md` (hardcoded in 8 files + routing.json) | `_agent/chorus-vault.md` |
 | Hooks | `hooks.json` paths ×2 incl. CoWork fallback glob | updated paths |
 | Docs/branding | README, SKILL.md, references, scaffold seeds, icons | rewrite pass (cosmetic but large) |
 
@@ -177,11 +177,14 @@ Repo hygiene on the fork: strip stale versioned `.plugin` artifacts from the
 tree (move to Gitea releases per ROADMAP-2.0), confirm `eval/` suites green
 as-is, tag the fork point.
 
-### Phase 1 — Mechanical rename (1–2 days)
-Everything in §3, with back-compat shims (env aliases, marker dual-probe,
-config import from echo paths). All existing tests pass under the new names.
-No behavior change. **Deliverable:** installable `chorus-memory` plugin that is
-ECHO-with-a-new-name.
+### Phase 1 — Mechanical rename (1–2 days) — DONE
+Everything in §3. All existing tests pass under the new names. No behavior
+change. **Deliverable:** installable `chorus-memory` plugin that is
+ECHO-with-a-new-name. *(Decided post-Phase-1: CHORUS is a **clean break** —
+fresh vaults on fresh machines for new users, so no ECHO back-compat: legacy
+`ECHO_*` env vars, echo-memory configs, `~/.echo-memory` state, and
+`_agent/echo-vault.md` markers are all ignored. Shims briefly existed and were
+removed.)*
 
 ### Phase 2 — Identity plumbing (1–2 days)
 `member` in config (+ `CHORUS_MEMBER`, baked-tier support, `config set --member`),
@@ -198,12 +201,10 @@ if the vault exists but your namespace doesn't — new members self-onboard),
 `cmd_load`/`cmd_scope`/heartbeat/inbox/triage/reflect retargeted to member
 paths, session logs under `sessions/<member>/`, member-prefixed Agent Log
 lines, `routing.json` route rows (with `<member>` pattern segment) + retired
-old paths, lint updates, `migrate.py` 4→5 (moves Jason's existing
-operator-preferences/current-context/heartbeat/inbox/sessions into
-`members/jason/…`, stamps `author: jason` vault-wide via sweep). Docs:
-vault-layout.md, routing-map.md, bootstrap.md rewritten.
-**Deliverable:** a real multi-member vault; the live ECHO vault migrates in
-place.
+old paths, lint updates, `migrate.py` 4→5 (for any alpha CHORUS vaults stood
+up between phases — there is no ECHO-vault adoption path; CHORUS vaults start
+fresh). Docs: vault-layout.md, routing-map.md, bootstrap.md rewritten.
+**Deliverable:** a real multi-member vault, bootstrapped from empty.
 
 ### Phase 4 — Shared-write hardening (1–2 days)
 Required lock on index writes with bounded retry/backoff, gate messages carry
@@ -246,3 +247,8 @@ retrieval/durability metrics. New icon.
    `_agent/members/<id>/inbox.md`; a shared `inbox/captures/group.md` holds
    unowned items (member-prefixed lines, idempotent appends), routed by
    whoever triages first. Both are probed at load and covered by triage.
+6. **Clean break from ECHO** *(added post-Phase-1)*. CHORUS vaults are fresh
+   vaults on fresh machines for new users — no ECHO adoption path, no legacy
+   `ECHO_*` env/config/state/marker compatibility. Jason's personal ECHO vault
+   continues unchanged on its own plugin and endpoint. If ECHO history is ever
+   wanted in CHORUS, it would be a one-off import exercise, out of scope.