test(adapters): seam selftests — deterministic mock cases + mission injection (#18)

- test-config: absent adapter defaults to pi; mock validates; unknown
  adapter exits 2; env exports MOSAIC_ADAPTER (24 cases total)
- test-task: mock adapter gate pass/mismatch (no provider needed),
  mismatch reason asserted, unknown adapter fails closed, mission section
  injected into generated prompt asserted by content (24 cases total)
- harness fixes: helpers defined before use; per-case config files (no
  cross-case leakage); newest-run selection for the live case; deduped
  accidentally duplicated live block

Closes #18

scripts/test-task.sh

@@ -30,6 +30,16 @@ check() {
     if [ "$2" = "0" ]; then PASS=$((PASS+1)); echo "ok   $1"; else FAIL=$((FAIL+1)); echo "FAIL $1"; fi
 }
 
+latest_reason() {
+    local latest
+    latest="$(ls -dt "$SANDBOX/data/runs"/r-* 2>/dev/null | head -1)"
+    [ -n "$latest" ] && node -e 'try{const r=JSON.parse(require("fs").readFileSync(process.argv[1],"utf8"));console.log(r.reason??"")}catch{console.log("")}' "$latest/result.json" 2>/dev/null
+}
+
+check() {
+    if [ "$2" = "0" ]; then PASS=$((PASS+1)); echo "ok   $1"; else FAIL=$((FAIL+1)); echo "FAIL $1"; fi
+}
+
 CONFIG="$SANDBOX/config.json"
 DATA_ROOT="$SANDBOX/data"
 mkdir -p "$DATA_ROOT"
@@ -92,6 +102,50 @@ $TASK validate "$SANDBOX/ok.json" >/dev/null 2>&1
 M2=$(stat -c %Y "$SANDBOX/ok.json")
 [ "$M1" = "$M2" ] && check "validation does not modify the task file" 0 || check "validation does not modify the task file" 1
 
+# ---------- adapter seam: deterministic mock cases (Docker, no provider) ----------
+if docker info >/dev/null 2>&1; then
+    good_task "$SANDBOX/ok.json"
+    mock_config() { # file adapter
+        cat > "$SANDBOX/$1" <<EOF
+{"configVersion":1,"environment":"development","dataRoot":"$SANDBOX/data","execution":{"backend":"docker","provider":"zai","model":"m","adapter":"$2"}}
+EOF
+    }
+
+    mock_config mock-adapters.json mock
+    expect_exit "mock adapter: gate passes on matching mock response" 0 -- \
+        env MOSAIC_CONFIG="$SANDBOX/mock-adapters.json" MOSAIC_MOCK_RESPONSE=MOSAIC_HELLO_OK \
+        scripts/run-task.sh run "$SANDBOX/ok.json"
+
+    expect_exit "mock adapter: expect-mismatch recorded" 1 -- \
+        env MOSAIC_CONFIG="$SANDBOX/mock-adapters.json" MOSAIC_MOCK_RESPONSE=SOMETHING_ELSE \
+        scripts/run-task.sh run "$SANDBOX/ok.json"
+    [ "$(latest_reason)" = "expect-mismatch" ] \
+        && check "mismatch reason recorded" 0 || check "mismatch reason recorded" 1
+
+    mock_config bad-adapter.json nonexistent
+    # The config layer rejects unknown adapters first, so run-task.sh fails
+    # closed (exit 1) before any container or run record exists.
+    expect_exit "unknown adapter fails closed" 1 -- \
+        env MOSAIC_CONFIG="$SANDBOX/bad-adapter.json" scripts/run-task.sh run "$SANDBOX/ok.json"
+
+    good_mission "$SANDBOX/m-ok.json"
+    printf '{"taskVersion":1,"id":"t-mission","prompt":"ignored by mock","mission":"m-ok.json"}' > "$SANDBOX/mission-task.json"
+    # Dedicated mission with distinctive directives for the injection assertion.
+    cat > "$SANDBOX/m-seam.json" <<'EOF'
+{"missionVersion":1,"id":"m-seam","objective":"Prove the mission injection point.","directives":["Seam directive A.","Seam directive B."]}
+EOF
+    printf '{"taskVersion":1,"id":"t-mission-seam","prompt":"ignored by mock","mission":"m-seam.json"}' > "$SANDBOX/seam-task.json"
+    expect_exit "mission task runs via mock adapter" 0 -- \
+        env MOSAIC_CONFIG="$SANDBOX/mock-adapters.json" MOSAIC_MOCK_RESPONSE=MOCKED \
+        scripts/run-task.sh run "$SANDBOX/seam-task.json"
+    grep -q 'MISSION (runtime)' "$SANDBOX/data/system-prompt.md" \
+        && grep -q 'Seam directive A.' "$SANDBOX/data/system-prompt.md" \
+        && check "mission section injected into generated prompt" 0 \
+        || check "mission section injected into generated prompt" 1
+else
+    echo "skip adapter seam cases (docker daemon unavailable)"
+fi
+
 # ---------- live: real runs (Docker + credentials required) ----------
 # On failure, surface the run record + agent stderr BEFORE the sandbox
 # cleanup destroys them. Never let a wrong-exit mask the real reason.
@@ -115,14 +169,15 @@ latest_reason() {
 }
 
 if docker info >/dev/null 2>&1; then
+    RUNS1=$(ls "$DATA_ROOT/runs" 2>/dev/null | wc -l)
     if scripts/run-task.sh run "$SANDBOX/ok.json" >/dev/null 2>&1; then
         PASS=$((PASS+1)); echo "ok   live hello task succeeds with exact marker"
     else
         FAIL=$((FAIL+1)); echo "FAIL live hello task succeeds with exact marker" >&2
         dump_latest_run
     fi
-    [ -f "$DATA_ROOT/runs" ] && RUNS1=$(ls "$DATA_ROOT/runs" | wc -l)
-    R1="$(ls "$DATA_ROOT/runs" | head -1)"
+
+    R1="$(ls -t "$DATA_ROOT/runs" | head -1)"   # newest = the live run above
     [ -f "$DATA_ROOT/runs/$R1/result.json" ] && check "result.json written in run dir" 0 || check "result.json written in run dir" 1
     node -e '
 const r = JSON.parse(require("fs").readFileSync(process.argv[1], "utf8"));