docs: chapters 02 + 03 of the guided tour (Part 1 complete)

02 — The cast of characters: equipment, EAP, MES, fab planner, AMHS,
operator.  Who initiates which conversation, why the equipment is
the passive side of HSMS by convention, how the AMHS handshake is
out-of-band relative to SECS.  Cross-references the relevant
namespace and test files for each actor.

03 — Vocabulary + a wafer's journey: follows one 300 mm wafer
end-to-end through a fab and labels every SECS message and acronym
that fires.  Introduces SVID / DVID / ECID / CEID / RPTID / ALID /
PPID / MDLN / SOFTREV / HCACK / ALCD / OFLACK / CAACK / SMACK / etc.
in context rather than as a list.  Includes one-screen reference
tables for the remaining acknowledge codes, T-timers in all four
contexts (HSMS / SECS-I / E84 / E30 communication state), and a
stream-by-stream summary.

Part 1 (Foundations) of the guided tour is now complete — a reader
who reads chapters 01–03 can describe the protocol stack, identify
the actors, and recognise every acronym they'll meet in Part 2.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docs/BENCHMARKS.md

@@ -0,0 +1,69 @@
+# Performance baseline
+
+Numbers from `build/secs_bench --requests 20000 --concurrency 16` on
+Docker / Ubuntu 24.04 inside Docker Desktop on macOS (M-series), single
+io_context thread.  Treat as **rough envelope for capacity planning**,
+not lab-grade benchmarks; re-run on your target hardware before
+sizing pods or VMs.
+
+## Round-trip throughput / latency
+
+| Scenario                         | Ops     | Elapsed |   Ops/sec  |  p50 µs |  p95 µs |  p99 µs |
+|----------------------------------|--------:|--------:|-----------:|--------:|--------:|--------:|
+| S1F1/F2 (header-only)            |   20000 |    0.14 |    ~140000 |      74 |     103 |     161 |
+| S1F3/F4 (32 SVIDs)               |   20000 |    0.25 |     ~79000 |     165 |     186 |     260 |
+| S6F11 push (W=0)                 |   20000 |    0.03 |    ~572000 |     n/a |     n/a |     n/a |
+
+**Read the table this way.** A real fab tool needs to handle tens to a
+few hundred S6F11 events/second sustained.  We're three orders of
+magnitude above that on the push path, two orders above on synchronous
+round-trips.  Throughput is not the bottleneck; latency tail under
+contention is.
+
+## Memory footprint
+
+A `ProcessJob` + `ControlJob` pair (no persistence enabled) is around
+**~450 bytes** of heap (1000 pairs ≈ 0.45 MiB, measured on a fresh
+process).  With persistence enabled add ~200 bytes of in-memory journal
+path tracking per record.
+
+| Active entity        | Approx bytes / instance |
+|----------------------|------------------------:|
+| PJ + CJ pair         |                    ~450 |
+| Carrier (no slots)   |                     ~80 |
+| Carrier slot         |                     ~24 |
+| Substrate            |                    ~120 |
+| Spool entry          | ~40 + encoded body size |
+
+A busy fab tool tracking 50 carriers × 25 slots, 200 substrates, 20
+active PJ+CJ pairs comes in well under 1 MiB of model state.  RSS will
+be dominated by the binary itself + asio's buffers (~10-20 MiB),
+not the model.
+
+## How to re-run
+
+```sh
+docker compose run --rm builder /app/build/secs_bench \
+    --requests 50000 \
+    --concurrency 32 \
+    --svid-count 32 \
+    --store-pairs 10000
+```
+
+Output is markdown — pipe to a file and commit it to your CI so
+regressions show up as diffs.
+
+## What this does NOT measure
+
+- **Real network**.  Loopback TCP has no MTU fragmentation, no
+  retransmits, no jitter.  Production HSMS over a fab control LAN will
+  see higher tail latency.
+- **Persistence write amplification**.  The bench runs with persistence
+  disabled.  Each store mutation with persistence enabled is one
+  atomic-rename to disk; on rotational media that limits you to a few
+  hundred mutations/sec.  SSD-backed deployments are fine.
+- **Concurrent S6F11 enable filtering**.  Real CEID emission gates on
+  the host's enable/disable list — this bench fires raw S6F11s.
+- **Multi-session HSMS-GS** dispatch overhead — single-session only.
+- **TLS-tunneled sockets** (via stunnel/sidecar) — these add ~50 µs
+  per round-trip on modern hardware.