README: Tier 4 is shipped, source 3 is shipped — drop the stale 🚧 marks

Closing the loop on the previous wave's commits. Tier 4 (real-malware
fetch + chunked upload + guest-side sha-verify + exec) and source 3
(perf stat collector) are both implemented and tested as of a88ac83;
the README still tagged them as TBD / planned. Fix.

- Tier 4 status: 🚧 → ✅ code; ⏳ awaiting operator's MalwareBazaar API
  key + at least one sha256 entry in manifest.toml. Same shape as the
  Tier-3 line.
- New "Tier 4 — real malware sample" section walks through the
  fetch → chunked upload → guest-side sha-verify → exec flow with
  links to the relevant code.
- Source 3 (perf stat): "🚧 planned" → "✅ opt-in via enable_perf".
- Snapshot/revert (revert_at_start / revert_at_end via QMP loadvm)
  added to the Orchestrator + drivers list.
- Test-count header updated 86 → 106.
- Stale issue links to closed #4 / #5 / #6 dropped.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -119,6 +119,28 @@ sets up `msfrpcd` (loopback only) as a hardened systemd unit;
 [`scripts/fetch-metasploitable2.sh`](scripts/fetch-metasploitable2.sh)
 pulls + sha256-verifies a target image from operator-supplied URL.
 
+### Tier 4 — *real malware sample, fetched + uploaded + executed*
+
+A manifest entry with a `sha256` flips its `Sample.kind` to `"real"`.
+The driver then bypasses the mimic profile and runs the real-binary
+path:
+
+1. [`tools/fetch_sample.py <sha256>`](tools/fetch_sample.py) pulls the
+   binary from MalwareBazaar (Auth-Key from
+   `samples/.bazaar.token` or `MALWAREBAZAAR_API_KEY`), unzips with the
+   standard `infected` password, sha-verifies, and lands at
+   `samples/store/<sha256>` (gitignored).
+2. At `infected_running`, the driver chunked-uploads the binary into
+   the shell session as 8 KiB base64 segments
+   (`exploits.workloads.chunked_real_binary_upload`). 256 KiB binaries
+   work without buffer-busting msfrpc.
+3. The session decodes, sha-verifies *again on the guest side*, chmods,
+   and execs only if the hash matches. Mismatch fail-stops the run.
+4. `meta.sample.sha256` + per-step events
+   (`real_binary_upload_begin`, `real_binary_verify`,
+   `sample_executed{kind=real}`) record exactly which binary was run
+   and when, so trainers can join cleanly.
+
 ### Tier maturity
 
 | Tier | What it gives | Status |
@@ -126,22 +148,22 @@ pulls + sha256-verifies a target image from operator-supplied URL.
 | 1 — real VM, idle | confidence the collectors read real KVM behaviour | ✅ done |
 | 2 — real VM, profile-driven workload | distinguishable in-guest envelopes per malware family | ✅ done |
 | 3 — real VM, real exploit fire + profile workload | honest `armed → infecting` transitions, driver v2 dispatch | ✅ code; ⏳ awaiting Metasploitable2 image + msfrpcd on a lab host |
-| 4 — real VM, real malware sample (MalwareBazaar fetch) | the full envelope we ultimately train on | 🚧 manifest schema ready (`sample.sha256` → `kind=real`); fetcher TBD |
+| 4 — real VM, real malware sample (MalwareBazaar fetch) | the full envelope we ultimately train on | ✅ code; ⏳ awaiting MalwareBazaar API key + sha256s in manifest |
 
-### Telemetry sources (all four wire into one episode dir)
+### Telemetry sources (all five wire into one episode dir)
 
 | # | Source                         | Vantage       | Role                |
 |---|--------------------------------|---------------|---------------------|
 | 1 | host `/proc/<qemu_pid>`        | outside       | oracle (label only) |
 | 2 | QEMU QMP queries               | outside       | oracle (label only) |
-| 3 | `perf stat -p <qemu_pid>`      | outside       | oracle (planned)    |
+| 3 | `perf stat -p <qemu_pid>`      | outside       | oracle (label only) |
 | 4 | Bridge pcap → 100 ms netflow   | gateway-side  | feature (deployable)|
 | 5 | In-guest agent (virtio-serial) | inside        | feature (deployable)|
 
-Sources 1, 2, 4, 5 are live as of this commit. The deploy/oracle split
-follows [`docs/threat-model.md`](docs/threat-model.md): only sources
-4 + 5 are usable as model *features* in the field — sources 1, 2, 3
-exist as labeling oracles only.
+All five are live. The deploy/oracle split follows
+[`docs/threat-model.md`](docs/threat-model.md): only sources 4 + 5
+are usable as model *features* in the field — sources 1, 2, 3 exist
+as labeling oracles only.
 
 For an interactive view of any episode (zoom/pan/hover), run:
 
@@ -152,7 +174,7 @@ tools/show_envelope.sh data/episodes/<episode_id>
 
 ---
 
-## Status (86/86 tests passing as of `b80986d`)
+## Status (106/106 tests passing as of `a88ac83`)
 
 **Pipeline (lab-host → Pi → tarball stored)**
 - ✅ Receiver app (HTTPS PUT, sha256-verified, idempotent) — running on the Pi behind Caddy with mTLS via the wg-pki client CA
@@ -166,16 +188,18 @@ tools/show_envelope.sh data/episodes/<episode_id>
 **Telemetry**
 - ✅ Source 1 — host `/proc/<qemu_pid>` @ 10 Hz
 - ✅ Source 2 — QEMU QMP @ 1 Hz
-- ✅ Source 4 — bridge pcap + 100 ms netflow bucketizer (pure-Python parser, no scapy/dpkt dep). Per-episode wiring in `EpisodeRunner` is tracked in [#6](http://maxgit.wg/spectral/CIS490/issues/6).
+- ✅ Source 3 — `perf stat -p <qemu_pid>` (opt-in via `enable_perf`; needs `CAP_SYS_ADMIN` / `CAP_PERFMON`)
+- ✅ Source 4 — bridge pcap + 100 ms netflow bucketizer (pure-Python parser, no scapy/dpkt dep), wired into `EpisodeRunner` via `bridge_iface`
 - ✅ Source 5 — in-guest agent over virtio-serial; cidata-embedded for first-boot install on Alpine
-- 🚧 Source 3 — `perf stat -p <qemu_pid>` ([#5](http://maxgit.wg/spectral/CIS490/issues/5))
 
 **Orchestrator + drivers**
 - ✅ Orchestrator v0 — phase-scheduled episode runner, ULID episode ids
+- ✅ Snapshot/revert via QMP `loadvm` (`revert_at_start` / `revert_at_end`) for clean baselines between episodes
 - ✅ Tier 2 driver — real Alpine VM, profile-driven in-guest workload over serial console
 - ✅ Tier 3 driver v2 — `MSFExploitDriver` + msfrpc client + per-sample workload dispatch; first canned module `vsftpd_234_backdoor.toml`
+- ✅ Tier 4 — `tools/fetch_sample.py` (MalwareBazaar by sha256) + chunked real-binary upload (`exploits.workloads.chunked_real_binary_upload`) + guest-side sha-verify-then-exec dispatch in `MSFExploitDriver`
 - ⏳ Tier 3 integration — needs operator to drop a Metasploitable2 image + run `scripts/install-msfrpcd.sh` on a lab host
-- 🚧 Tier 4 — MalwareBazaar fetch by sha256 (manifest schema is ready; tracked in [#4](http://maxgit.wg/spectral/CIS490/issues/4))
+- ⏳ Tier 4 integration — needs operator's MalwareBazaar API key + at least one `sha256` entry in `samples/manifest.toml`
 
 **Fleet (multi-VM, multi-host data generation)**
 - ✅ Resource-aware capacity detector (cores / RAM / load) — `orchestrator/fleet.py`