Implement M6C bounded cache and VFS

CHANGELOG.md

@@ -1,5 +1,26 @@
 # Changelog
 
+## M6C Bounded Cache and VFS candidate — 2026-07-27
+
+- Adopted Soma OS as the temporary user-facing working identity while retaining
+  historical tags and internal crate identifiers.
+- Added a 16-sector, allocation-free, read-through LRU block cache.
+- Made the M6C dirty-state policy explicit: every persistent write is rejected
+  before transport and the cache must retain zero dirty entries.
+- Added live first-miss/repeat-hit evidence against the accepted virtio device.
+- Added fixed inode, superblock, mount, canonical path, directory, and backend
+  contracts.
+- Added bounded absolute-path normalization with component and depth limits.
+- Added a four-entry mount table with component-boundary longest-prefix lookup.
+- Added a 32-entry generation-protected user file-handle table.
+- Adapted RAMFS and shell file operations behind the VFS contract.
+- Added `cache` and `mounts` diagnostics.
+- Added capability registry version 6 and mandatory M6B regression evidence.
+
+M6C does not mount a persistent filesystem and cannot leave persistent dirty
+data. Read-only FAT32 remains the M6D gate; persistent writes remain deferred
+until corruption, recovery, and power-loss behavior are designed and tested.
+
 ## M6B Virtio Block Transport candidate — 2026-07-26
 
 - Architecture-independent 512-byte sector block-device contract.

Makefile

@@ -4,7 +4,7 @@ SHELL := /usr/bin/env bash
 
 help:
 	@printf '%s\n' \
-	  'SanjuOS developer commands:' \
+	  'Soma OS developer commands:' \
 	  '  make setup   Install the Rust target used by the UEFI loader' \
 	  '  make source-check  Validate critical source and UEFI ABI invariants' \
 	  '  make user-programs  Rebuild the embedded Ring 3 ELF programs' \

PROJECT.md

@@ -1,14 +1,14 @@
 # Project Charter
 
-- Working name: SanjuOS
+- Working name: Soma OS
 - Start date: 2026-07-21
 - Product owner: Sanju
 - Architecture: x86-64
 - Firmware: UEFI 2.x
 - Primary language: Rust 2024
-- Accepted checkpoint: M6A PCI and Storage Discovery
-- Immutable release: `v0.0.9-m6a`
-- Current development checkpoint: M6B virtio block transport
+- Accepted checkpoint: M6B Virtio Block Transport
+- Immutable release: `v0.0.10-m6b`
+- Current development checkpoint: M6C bounded cache and VFS
 - Deployment policy: QEMU only until physical-install safety gates pass
 
 ## Mission
@@ -21,12 +21,12 @@ Development is grouped into major milestone batches. Small formatting or CI corr
 
 ## Current objective
 
-Activate the dedicated QEMU virtio block target behind an
-architecture-independent sector contract. Validate modern PCI capabilities,
-feature negotiation, DMA queue ownership, a known-sector read, and a confined
-write/readback/restore transaction.
+Add an allocation-free, fixed-capacity read-through cache over the accepted
+virtio block transport. Establish bounded inode, superblock, mount, canonical
+path, directory, and generation-protected user file-handle contracts. Adapt
+RAMFS behind that VFS boundary without enabling persistent writes.
 
 ## Next major objective
 
-Add a fixed-capacity block cache and VFS contracts without enabling persistent
-filesystem writes.
+Validate and mount a dedicated FAT32 image read-only, then expose bounded
+persistent directory listing and file reads through the accepted VFS.

README.md

@@ -1,17 +1,17 @@
-# SanjuOS
+# Soma OS
 
-![SanjuOS logo](assets/branding/sanjuos-logo.png)
-
-SanjuOS is an independent, Rust-first desktop operating-system project. It is
+Soma OS is the current working identity of an independent, Rust-first desktop
+operating-system project. Historical release tags and internal `sanju-*` crate
+identifiers remain unchanged until the public product identity is frozen. It is
 not a Linux distribution. Development proceeds through emulator-verified kernel
 milestones before any physical-disk work.
 
-## Current checkpoint: M6B Virtio Block Transport
+## Current checkpoint: M6C Bounded Cache and VFS
 
-The accepted baseline entering this phase was the Foundation Hardening Phase 2
-candidate. M0 through FH2 proved UEFI ownership transfer, protected kernel
+The accepted baseline entering this phase is `v0.0.10-m6b`. M0 through FH2
+proved UEFI ownership transfer, protected kernel
 execution, interrupts, Ring 3 entry, `SYSCALL`/`SYSRET`, ELF64 loading,
-recoverable user faults, physical ownership, and a fresh SanjuOS page-table
+recoverable user faults, physical ownership, and a fresh Soma OS page-table
 root.
 
 The accepted `v0.0.8-fh3` release turned the process runtime into an active
@@ -51,10 +51,21 @@ M6B implements that gate on the dedicated QEMU test disk:
 - a seeded read test plus a disposable write/readback/restore transaction;
 - a `block` shell diagnostic and exact QEMU acceptance evidence.
 
+M6C builds the filesystem boundary without enabling persistent writes:
+
+- a 16-sector, allocation-free, read-through LRU cache;
+- one live first-miss/repeat-hit probe proving the second read avoids transport;
+- a hard read-only cache policy with zero dirty entries;
+- fixed inode, superblock, mount, canonical path, and directory contracts;
+- component-boundary mount resolution and bounded `.`/`..` normalization;
+- generation-protected user file handles that reject stale identifiers;
+- RAMFS accessed through the same VFS interface reserved for FAT32;
+- `cache` and `mounts` shell diagnostics plus exact smoke evidence.
+
 ## Shell commands
 
 ```text
-help version userspace uptime memory irq tasks pci block ls cat write echo clear
+help version userspace uptime memory irq tasks pci block cache mounts ls cat write echo clear
 ```
 
 ## Build and verify
@@ -77,20 +88,22 @@ boot/uefi/          UEFI orchestration and x86-64 platform implementation
 kernel/             Boot contracts, memory ownership, allocators, kernel models
 capabilities/       Canonical capability registry and generated smoke evidence
 user/programs/      Position-independent Ring 3 assembly programs
-assets/branding/    Approved SanjuOS graphical logo
+assets/branding/    Historical and future product identity assets
 scripts/            Build, generation, ABI, QEMU, and validation automation
 docs/               Requirements, architecture, ADRs, testing, security, process
 ```
 
 ## Current boundary
 
-M6B and FH3 remain single-core and PIT-driven. Block completion is synchronous
+M6C and FH3 remain single-core and PIT-driven. Block completion is synchronous
 and polling, one request is outstanding at a time, and only the explicitly
-identified disposable QEMU disk is used. The combined EFI-stub kernel still
-retains a bounded identity mapping while a separate high-half kernel image is
-designed. A block cache, VFS, read-only FAT32, persistent writes, physical-disk
-installation, graphics, SMP, and local APIC timers remain later gates.
+identified disposable QEMU disk is used. The cache cannot issue writes and
+cannot contain dirty entries. RAMFS remains the only writable filesystem. The
+combined EFI-stub kernel still retains a bounded identity mapping while a
+separate high-half kernel image is designed. Read-only FAT32, persistent
+writes, physical-disk installation, graphics, SMP, and local APIC timers remain
+later gates.
 
 ## Safety
 
-SanjuOS remains emulator-only. Do not install it on a physical disk.
+Soma OS remains emulator-only. Do not install it on a physical disk.

SECURITY.md

@@ -1,6 +1,6 @@
 # Security Policy
 
-SanjuOS is pre-alpha research software and must not be used to protect sensitive data or replace a production operating system.
+Soma OS is pre-alpha research software and must not be used to protect sensitive data or replace a production operating system.
 
 ## Reporting