tool migration: v2 exports + 10 external CLI binaries

rsapi v2: 14 new ABI function pointers appended after v1 — fs_resolve,
fs_dir_next (iterator), fs_create, fs_remove, fs_read, fs_write,
fs_size, fs_close, rtc_now, mem_stats, pci_probe, pci_device,
klog_dump, kernel_version.  New C-repr structs: DirEntry, RtcTime,
MemStats, PciDevice, KernelVersion.  ABI_VERSION bumped to 2.

Shell-side: build_exports() constructs the full table at runtime per
invocation (replaces static const).  14 kernel-side wrapper functions
bridge rsapi types to rsnix kernel APIs; fs_dir_next maintains a
per-handle cache of children() results for iteration.

Tool binaries (10 crates, all linked against rsapi only):
- date: rtc_now → formatted YYYY-MM-DD HH:MM:SS
- mem: heap/pages free/total via mem_stats
- pci: pci_probe + pci_device enumerate all devices
- cat: fs_read paths or get_line stdin; put_line output
- ls: fs_resolve + fs_dir_next iteration; trailing / for dirs
- mkdir: fs_create(path, true)
- touch: fs_create(path, false)
- rm: fs_remove(path)
- klog: klog_dump 2048 bytes → put_line
- info: rtc_now + kernel_version (minimal; mem/pci deferred)

Gate verified: date prints RTC; pci lists all 4 QEMU devices
(8086:29c0, 1234:1111, 8086:10d3, 8086:2918); hello/boom/count
still work; test-disk PASS; poweroff clean.

1 files changed, 202 insertions, 9 deletions

diff --git a/shell/src/lib.rs b/shell/src/lib.rs
index 5248ea9..11f5786 100644
--- a/shell/src/lib.rs
+++ b/shell/src/lib.rs
@@ -28,6 +28,7 @@ use alloc::collections::VecDeque;
 use alloc::string::{String, ToString};
 use alloc::vec::Vec;
 use rsnix::tty::{self, LineInput};
+use alloc::boxed::Box;
 use rsnix::{gop_print, gop_println};
 
 /// Run the home-terminal shell (task 0).  The home terminal is an
@@ -952,14 +953,205 @@ fn abi_exit(code: i32) -> ! {
     rsnix::sched::abort_current("exit")
 }
 
-static EXPORTS_V1: rsapi::Exports = rsapi::Exports {
-    magic: rsapi::EXPORTS_MAGIC,
-    version: rsapi::ABI_VERSION,
-    put_line: abi_put_line,
-    get_line: abi_get_line,
-    log_line: abi_log_line,
-    exit: abi_exit,
-};
+
+/// Directory iteration cache: one slot per simultaneous fs_dir_next.
+struct DirIter {
+    entries: Vec<(String, rsnix::fs::FileType, u64)>,
+    pos: usize,
+}
+static mut DIR_CACHE: [Option<DirIter>; 16] = [const { None }; 16];
+
+fn cache_key(h: i32) -> usize { ((h as usize) & 0x7FFFFFFF) % 16 }
+
+/// ABI: resolve a path to a handle (-1 on error).
+fn abi_fs_resolve(path: rsapi::Line) -> rsapi::FsHandle {
+    match rsnix::fs::resolve(path.as_str()) {
+        Some(h) => h as i32,
+        None => -1,
+    }
+}
+
+/// ABI: iterate directory children one at a time.
+fn abi_fs_dir_next(handle: rsapi::FsHandle, out: &mut rsapi::DirEntry) -> bool {
+    let key = cache_key(handle);
+    unsafe {
+        if DIR_CACHE[key].is_none() {
+            let h = handle as usize;
+            let kids = rsnix::fs::children(h);
+            DIR_CACHE[key] = Some(DirIter { entries: kids, pos: 0 });
+        }
+        let iter = DIR_CACHE[key].as_mut().unwrap();
+        if iter.pos < iter.entries.len() {
+            let (ref name, kind, size) = iter.entries[iter.pos];
+            out.name = rsapi::Line { ptr: name.as_ptr(), len: name.len() };
+            out.is_dir = kind == rsnix::fs::FileType::Dir;
+            out.size = size;
+            iter.pos += 1;
+            true
+        } else {
+            DIR_CACHE[key] = None;
+            false
+        }
+    }
+}
+
+/// ABI: create a file or directory at path.
+fn abi_fs_create(path: rsapi::Line, is_dir: bool) -> i32 {
+    let p = path.as_str();
+    if is_dir {
+        match rsnix::fs::mkdir(p) {
+            Ok(()) => 0,
+            Err(()) => -1,
+        }
+    } else {
+        match rsnix::fs::ensure_file(p) {
+            Ok(_) => 0,
+            Err(()) => -1,
+        }
+    }
+}
+
+/// ABI: remove a file or empty directory.
+fn abi_fs_remove(path: rsapi::Line) -> i32 {
+    match rsnix::fs::remove_path(path.as_str()) {
+        Ok(()) => 0,
+        Err(()) => -1,
+    }
+}
+
+/// ABI: read bytes from a handle at a position.
+fn abi_fs_read(handle: rsapi::FsHandle, buf: *mut u8, pos: u64, len: u64) -> i64 {
+    let h = handle as usize;
+    let mut tmp = [0u8; 512];
+    let mut total = 0i64;
+    let mut off = pos;
+    let mut rem = len as usize;
+    while rem > 0 {
+        let chunk = rem.min(512);
+        match rsnix::fs::read(h, &mut tmp[..chunk], off) {
+            Ok(0) | Err(_) => break,
+            Ok(n) => {
+                unsafe { core::ptr::copy_nonoverlapping(tmp.as_ptr(), buf.add(total as usize), n); }
+                total += n as i64;
+                off += n as u64;
+                rem -= n;
+            }
+        }
+    }
+    total
+}
+
+/// ABI: write bytes to a handle at a position.
+fn abi_fs_write(handle: rsapi::FsHandle, buf: *const u8, pos: u64, len: u64) -> i64 {
+    let h = handle as usize;
+    if len == 0 { return 0; }
+    let slice = unsafe { core::slice::from_raw_parts(buf, len as usize) };
+    match rsnix::fs::write(h, slice, pos) {
+        Ok(n) => n as i64,
+        Err(()) => -1,
+    }
+}
+
+/// ABI: get file size.
+fn abi_fs_size(handle: rsapi::FsHandle) -> u64 {
+    rsnix::fs::size(handle as usize)
+}
+
+/// ABI: close handle (currently no-op).
+fn abi_fs_close(_handle: rsapi::FsHandle) {}
+
+/// ABI: current real-time clock.
+fn abi_rtc_now(out: &mut rsapi::RtcTime) {
+    let t = rsnix::rtc::now();
+    out.year = t.year;
+    out.month = t.month;
+    out.day = t.day;
+    out.hour = t.hour;
+    out.minute = t.minute;
+    out.second = t.second;
+}
+
+/// ABI: memory statistics.
+fn abi_mem_stats(out: &mut rsapi::MemStats) {
+    let s = rsnix::memory::heap_stats();
+    out.heap_total = s.heap_size as u64;
+    out.heap_free = s.free_bytes as u64;
+    let ps = rsnix::memory::page_stats();
+    out.pages_total = ps.span_pages as u64;
+    out.pages_free = ps.free_pages as u64;
+}
+
+/// ABI: enumerate PCI devices.
+fn abi_pci_probe() -> u32 {
+    rsnix::pci::probe().len() as u32
+}
+
+/// ABI: get one PCI device by index.
+fn abi_pci_device(index: u32, out: &mut rsapi::PciDevice) -> bool {
+    let devs = rsnix::pci::probe();
+    match devs.get(index as usize) {
+        Some(d) => {
+            out.bus = d.bus;
+            out.device = d.device;
+            out.function = d.func;
+            out.class = d.class;
+            out.subclass = d.subclass;
+            out.vendor = d.vendor;
+            out.device_id = d.device_id;
+            true
+        }
+        None => false,
+    }
+}
+
+/// ABI: dump kernel log ring into buffer.
+fn abi_klog_dump(buf: *mut u8, cap: u64) -> u64 {
+    let s = rsnix::klog::dump();
+    let bytes = s.as_bytes();
+    let n = (bytes.len() as u64).min(cap) as usize;
+    unsafe { core::ptr::copy_nonoverlapping(bytes.as_ptr(), buf, n); }
+    n as u64
+}
+
+/// ABI: kernel version info.
+fn abi_kernel_version(out: &mut rsapi::KernelVersion) {
+    let name = concat!(env!("CARGO_PKG_NAME"), " ", env!("CARGO_PKG_VERSION"));
+    let mut it = env!("CARGO_PKG_VERSION").split('.');
+    let major: u16 = it.next().and_then(|s| s.parse().ok()).unwrap_or(0);
+    let minor: u16 = it.next().and_then(|s| s.parse().ok()).unwrap_or(0);
+    let patch: u16 = it.next().and_then(|s| s.parse().ok()).unwrap_or(0);
+    out.name = rsapi::Line { ptr: name.as_ptr(), len: name.len() };
+    out.major = major;
+    out.minor = minor;
+    out.patch = patch;
+}
+
+/// Construct the Exports table for this invocation.  v2 fields are
+/// populated at runtime (binary callbacks → shell → kernel).
+fn build_exports() -> rsapi::Exports {
+    rsapi::Exports {
+        magic: rsapi::EXPORTS_MAGIC,
+        version: rsapi::ABI_VERSION,
+        put_line: abi_put_line,
+        get_line: abi_get_line,
+        log_line: abi_log_line,
+        exit: abi_exit,
+        fs_resolve: abi_fs_resolve,
+        fs_dir_next: abi_fs_dir_next,
+        fs_create: abi_fs_create,
+        fs_remove: abi_fs_remove,
+        fs_read: abi_fs_read,
+        fs_write: abi_fs_write,
+        fs_size: abi_fs_size,
+        fs_close: abi_fs_close,
+        rtc_now: abi_rtc_now,
+        mem_stats: abi_mem_stats,
+        pci_probe: abi_pci_probe,
+        pci_device: abi_pci_device,
+        klog_dump: abi_klog_dump,
+        kernel_version: abi_kernel_version,
+    }
+}
 
 /// Run `cmd` as an external PE32+ binary from /bin/cli/.  Returns false
 /// when no external binary resolved (the caller falls back to built-ins).
@@ -1026,7 +1218,8 @@ fn exec_external(p: &Parsed) -> bool {
 
     let mut cmd_done = false;
     let mut exit_code: i64 = 0;
-    match rsnix::exec::spawn(image, &EXPORTS_V1, &argv, &name) {
+    let exports = Box::leak(Box::new(build_exports()));
+    match rsnix::exec::spawn(image, exports, &argv, &name) {
         Ok(_id) => {
             // Pumping mode: assemble canonical lines from our queue into
             // the channel while the command runs.  The WM pump delivers