agents: they never spoke, the decoder lost the disc, and both shared one state dir

Three defects, all mine, found by checking instead of assuming.

**They never exchanged a word.** SendMessage=0, ListAgents=0 across both new
sessions. PROTOCOL.md specified in detail what a message MAY and MAY NOT do and
never said how to send one or that the other agent was addressable -- they knew
that last time only because the human told them directly, and rebuilding with
fresh volumes wiped it. Policy without mechanism is prose. Now documented with
the two addresses, a worked example, and an instruction to introduce themselves
on the first iteration rather than waiting to have a question.

**The decoder lost the disc and the ISO.** They used to arrive inside the project
mount and silently stopped when /work became a clone. Silently is the word: the
disc-gated tests SELF-SKIP without SYLPHEED_DISC and report green, so a whole
test suite would have passed while measuring nothing. Both are now mounted
explicitly, the ISO at a stable path so run-canary does not depend on host
directory names.

**Both agents shared one Claude state directory.** They share the host's
~/.claude, and once both working directories became /work they resolved to the
same projects/-work/ -- two supposedly independent agents writing to one place,
which undoes the point of separate checkouts. Each now has its own volume, seeded
once from the host with credentials only, so a token refresh writes locally and
neither can corrupt the host's auth.

Also widened the pacing rule. It banned ScheduleWakeup by name; the decoder then
scheduled itself an hourly cron job -- not harmful, but the same instinct that
ended a run yesterday, through a door I had left open. Now: no self-scheduling by
any route.

Mount audit after the changes: shared and intentional are the exchange volume and
the read-only credential seed. Everything else -- repo, Claude state, cargo,
target, canary, disc, ISO -- is per agent or one-sided.

docker/decoder/entrypoint.sh

@@ -124,6 +124,24 @@ fi
 mkdir -p /exchange/files 2>/dev/null || true
 
 # ── Claude Code config ───────────────────────────────────────────────────────
+# ── Claude state: this agent's own, seeded once from the host ───────────────
+# Isolated per agent. Both working directories are /work, and Claude Code keys
+# its per-project state off the working directory -- so a SHARED ~/.claude put
+# two independent agents in the same projects/-work/ directory, which undoes the
+# point of giving them separate checkouts.
+#
+# Seeded rather than shared because credentials live in .credentials.json and a
+# token refresh must be able to write. Copying once means each agent refreshes
+# its own token and neither can corrupt the host's.
+if [ -d "$HOME/.claude.seed" ] && [ ! -s "$HOME/.claude/.credentials.json" ]; then
+  mkdir -p "$HOME/.claude"
+  cp -a "$HOME/.claude.seed/.credentials.json" "$HOME/.claude/" 2>/dev/null || true
+  for f in settings.json CLAUDE.md; do
+    [ -e "$HOME/.claude.seed/$f" ] && cp -a "$HOME/.claude.seed/$f" "$HOME/.claude/" 2>/dev/null || true
+  done
+  echo "[entrypoint] seeded ~/.claude from the host (credentials only)"
+fi
+
 # Seed ~/.claude.json from the host's read-only copy, then stamp onboarding as
 # complete. Claude Code re-runs its first-run wizard whenever
 # lastOnboardingVersion differs from the installed version — so a container with

docker/decoder/sylph-decoder

@@ -104,6 +104,12 @@ docker_args() {
     # and carries our instrumentation. Read-write: building probes into it is
     # real work, not a side effect.
     -v "${SYLPH_CANARY:-$HOME/RE Project Sylpheed/xenia-canary}:/canary"
+    # The disc and the ISO. These used to arrive inside the project mount and
+    # silently stopped when /work became a clone -- silently because the
+    # disc-gated tests SELF-SKIP without SYLPHEED_DISC and report green, which
+    # is the most expensive kind of missing mount.
+    -v "${SYLPH_DISC:-$PROJECT/sylph_extract}:/disc:ro"
+    -e "SYLPHEED_DISC=/disc"
     # The shared exchange: transient files with provenance, outside git history.
     -v "sylpheed-exchange:/exchange"
     -e "PROJECT_DIR=/work"
@@ -115,7 +121,8 @@ docker_args() {
     # The state dir is shared read-write: credentials live in
     # .claude/.credentials.json, so token refresh needs to write, and this is
     # also what carries the project memory across.
-    -v "${SYLPH_CLAUDE_HOME:-$HOME/.claude}:/sylph-home/re/.claude"
+    -v "sylpheed-decoder-claude:/sylph-home/re/.claude"
+    -v "${SYLPH_CLAUDE_HOME:-$HOME/.claude}:/sylph-home/re/.claude.seed:ro"
     # ~/.claude.json sits BESIDE that directory and holds `hasCompletedOnboarding`.
     # Mounted READ-ONLY at a staging path: the entrypoint copies it to
     # ~/.claude.json and stamps onboarding as done. Sharing the file directly
@@ -165,7 +172,15 @@ docker_args() {
   [ -n "${SYLPH_VULKAN:-}" ]      && _out+=(-e "SYLPH_VULKAN=$SYLPH_VULKAN")
   [ -n "${SYLPH_REMOTE:-}" ]      && _out+=(-e "SYLPH_REMOTE=$SYLPH_REMOTE")
   [ -n "${SYLPH_REMOTE_NAME:-}" ] && _out+=(-e "SYLPH_REMOTE_NAME=$SYLPH_REMOTE_NAME")
-  [ -n "${SYLPH_ISO:-}" ]         && _out+=(-e "SYLPH_ISO=$SYLPH_ISO")
+  # The ISO Canary boots. Default resolves the retail image beside the project;
+  # mounted at a stable in-container path so run-canary does not depend on the
+  # host's directory names.
+  _iso="${SYLPH_ISO:-$PROJECT/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja).iso}"
+  if [ -f "$_iso" ]; then
+    _out+=(-v "$_iso:/iso/game.iso:ro" -e "SYLPH_ISO=/iso/game.iso")
+  else
+    echo "==> NOTE: no ISO at $_iso -- Canary has nothing to boot." >&2
+  fi
 
   # ── GPU ──
   # Three distinct cases, and conflating them is how you end up believing you