feat(v4.0.0): the system boots from a nucleus and loads its capsules

One boot, v4/system/boot.c, for both products: it starts the nucleus image,
finds each capsule in the baked capsule directory, recomputes its hash,
checks its signature, gives its blocks to the node a line at a time, and
prints PARITY:V4_NUCLEUS, PARITY:V4_CAPSULE and PARITY:OK before the prompt.
A line the node does not accept ends the boot with the capsule, block and
line named.  docs/v4.0.0/NUCLEUS.md.

- hosted Linux product for amd64, aarch64 and riscv64 (make -C v4 hosted);
  make -C v4 hosted-check boots all three and requires identical output
- the kernel's v4 entry (STARFORTH_V4=1) calls the same boot
- capsules/v4/forth79.4th, block 6000: no definitions yet
- mkimage builds the nucleus only; no FORTH source is compiled at build time
- capsule_blocks.c: the Block-header parse, free of any VM, for every loader

Verified: make -C v4 test passes; hosted-check passes on the three ISAs with
the same hashes; the kernel compiles with STARFORTH_V4=1 on the three.
Not verified: no bare-metal boot of v4 has been run.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

kernel/Makefile

@@ -60,6 +60,9 @@ $(eval $(call kconfig_bool,PARITY_MODE,0))
 # StarForth VM integration (default: enabled)
 $(eval $(call kconfig_bool,STARFORTH_ENABLE_VM,1))
 
+# StarForth v4 at a single prompt in place of the v3 VM (default: off)
+$(eval $(call kconfig_bool,STARFORTH_V4,0))
+
 # Monolithic build — loader + kernel compiled together (default: enabled)
 MONOLITHIC ?= 1
 
@@ -597,6 +600,30 @@ LOADER_VM_OBJS := $(patsubst v3/src/%.c,$(LOADER_OBJ_DIR)/vmcore/%.o,$(VM_CORE_S
 KERNEL_VM_OBJS := $(patsubst v3/src/%.c,$(KERNEL_OBJ_DIR)/vmcore/%.o,$(VM_CORE_SRCS))
 endif
 
+# ------------------------------------------------------------------------------
+# StarForth v4 (STARFORTH_V4=1): the golden model of the F18-derived engine,
+# v4/src, and the nucleus image v4's own Makefile builds on this machine from
+# v4/capsule (docs/v4.0.0/NUCLEUS.md).  The node is the host node's size, with 64-bit cells, as every
+# ISA this kernel boots on has (DECOMPOSITION.md D-5), so the image is the
+# same file for all three.
+# ------------------------------------------------------------------------------
+ifeq ($(STARFORTH_V4),1)
+V4_DEFS := -DSTARFORTH_V4=1 -Iv4/include \
+    -DV4_CELL_BITS=64 -DV4_NODE_WORDS=16384 -DV4_DATA_RING=30 -DV4_RET_RING=31
+KERNEL_CFLAGS += $(V4_DEFS)
+LOADER_CFLAGS += $(V4_DEFS)
+
+V4_ENGINE_SRCS := $(addprefix v4/src/,node.c exec.c stack.c iword.c heat.c guard.c image.c)
+V4_IMAGE_C     := $(BUILD_DIR)/v4_image_64.c
+
+LOADER_EXTRA_SRCS += $(KERNEL_SRC)/v4/sk_v4.c
+KERNEL_EXTRA_SRCS += $(KERNEL_SRC)/v4/sk_v4.c
+# v4/system/boot.c is the boot the hosted v4 system runs too: nucleus, then
+# the capsules from this kernel's own capsule directory, then the prompt.
+LOADER_V4_OBJS := $(patsubst v4/src/%.c,$(LOADER_OBJ_DIR)/v4engine/%.o,$(V4_ENGINE_SRCS)) $(LOADER_OBJ_DIR)/v4engine/v4_image.o $(LOADER_OBJ_DIR)/v4system/boot.o
+KERNEL_V4_OBJS := $(patsubst v4/src/%.c,$(KERNEL_OBJ_DIR)/v4engine/%.o,$(V4_ENGINE_SRCS)) $(KERNEL_OBJ_DIR)/v4engine/v4_image.o $(KERNEL_OBJ_DIR)/v4system/boot.o
+endif
+
 LOADER_SRCS := $(LOADER_SRCS_BASE) $(LOADER_EXTRA_SRCS)
 KERNEL_SRCS := $(KERNEL_SRCS_BASE) $(KERNEL_EXTRA_SRCS)
 
@@ -605,12 +632,14 @@ LOADER_OBJS := \
     $(patsubst $(KERNEL_SRC)/%.c,$(LOADER_OBJ_DIR)/%.o,$(LOADER_ARCH_SRCS)) \
     $(patsubst $(KERNEL_SRC)/%.S,$(LOADER_OBJ_DIR)/%.o,$(LOADER_ASM)) \
     $(LOADER_VM_OBJS) \
+    $(LOADER_V4_OBJS) \
     $(CAPSULE_GENERATED_OBJ)
 
 KERNEL_OBJS := \
     $(patsubst $(KERNEL_SRC)/%.c,$(KERNEL_OBJ_DIR)/%.o,$(KERNEL_SRCS)) \
     $(patsubst $(KERNEL_SRC)/%.S,$(KERNEL_OBJ_DIR)/%.o,$(KERNEL_ASM)) \
     $(KERNEL_VM_OBJS) \
+    $(KERNEL_V4_OBJS) \
     $(CAPSULE_GENERATED_KOBJ)
 
 # ==============================================================================
@@ -733,6 +762,41 @@ else
 	@$(LOADER_CC) $(VMCORE_CFLAGS_COMMON) $(filter-out -I$(KERNEL_INC),$(LOADER_CFLAGS)) -c $< -o $@
 endif
 
+# StarForth v4: the capsule image, built on this machine by v4's Makefile, and
+# the engine, compiled like any other kernel source.
+ifeq ($(STARFORTH_V4),1)
+$(V4_IMAGE_C): FORCE
+	@mkdir -p $(dir $@)
+	@echo "  V4IMG   v4/capsule -> $@"
+	@$(MAKE) --no-print-directory -C v4 CC=cc build/v4_image_64.c
+	@cmp -s v4/build/v4_image_64.c $@ || cp v4/build/v4_image_64.c $@
+
+$(LOADER_OBJ_DIR)/v4engine/v4_image.o: $(V4_IMAGE_C) | $(LOADER_OBJ_DIR)
+	@mkdir -p $(dir $@)
+	@echo "CC (loader) $<"
+	@$(LOADER_CC) $(LOADER_CFLAGS) -c $< -o $@
+$(KERNEL_OBJ_DIR)/v4engine/v4_image.o: $(V4_IMAGE_C) | $(KERNEL_OBJ_DIR)
+	@mkdir -p $(dir $@)
+	@echo "CC (kernel) $<"
+	@$(CC) $(KERNEL_CFLAGS) -c $< -o $@
+$(LOADER_OBJ_DIR)/v4system/%.o: v4/system/%.c | $(LOADER_OBJ_DIR)
+	@mkdir -p $(dir $@)
+	@echo "CC (loader) $<"
+	@$(LOADER_CC) $(LOADER_CFLAGS) -c $< -o $@
+$(KERNEL_OBJ_DIR)/v4system/%.o: v4/system/%.c | $(KERNEL_OBJ_DIR)
+	@mkdir -p $(dir $@)
+	@echo "CC (kernel) $<"
+	@$(CC) $(KERNEL_CFLAGS) -c $< -o $@
+$(LOADER_OBJ_DIR)/v4engine/%.o: v4/src/%.c | $(LOADER_OBJ_DIR)
+	@mkdir -p $(dir $@)
+	@echo "CC (loader) $<"
+	@$(LOADER_CC) $(LOADER_CFLAGS) -c $< -o $@
+$(KERNEL_OBJ_DIR)/v4engine/%.o: v4/src/%.c | $(KERNEL_OBJ_DIR)
+	@mkdir -p $(dir $@)
+	@echo "CC (kernel) $<"
+	@$(CC) $(KERNEL_CFLAGS) -c $< -o $@
+endif
+
 # Compile loader assembly sources
 $(LOADER_OBJ_DIR)/%.o: $(KERNEL_SRC)/%.S | $(LOADER_OBJ_DIR)
 	@mkdir -p $(dir $@)
@@ -1337,6 +1401,7 @@ info:
 	@echo "Loader output:   $(LOADER_EFI)"
 	@echo "Kernel output:   $(KERNEL_ELF)"
 	@echo "VM integration:  $(STARFORTH_ENABLE_VM)"
+	@echo "StarForth v4:    $(STARFORTH_V4)"
 	@echo "Monolithic:      $(MONOLITHIC)"
 
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