p2: digest with in-sift FIFO, SQLite caches, Honcho context, recover

Dixie is capped (max_inflight 2, queue_depth 8, queue_wait 20s) and
never queued on llama-server. Streaming chat, thinking off, 45s
fallback to clean. Digest and chunk-embedding caches are
content-addressed SQLite (Honcho context is not cached). Recover
uses the guarded Fetcher. guardian-star is refused in code.

vendor/golang.org/x/sys/unix/sysvshm_unix.go

@@ -0,0 +1,51 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build (darwin && !ios) || linux || zos
+
+package unix
+
+import "unsafe"
+
+// SysvShmAttach attaches the Sysv shared memory segment associated with the
+// shared memory identifier id.
+func SysvShmAttach(id int, addr uintptr, flag int) ([]byte, error) {
+	addr, errno := shmat(id, addr, flag)
+	if errno != nil {
+		return nil, errno
+	}
+
+	// Retrieve the size of the shared memory to enable slice creation
+	var info SysvShmDesc
+
+	_, err := SysvShmCtl(id, IPC_STAT, &info)
+	if err != nil {
+		// release the shared memory if we can't find the size
+
+		// ignoring error from shmdt as there's nothing sensible to return here
+		shmdt(addr)
+		return nil, err
+	}
+
+	// Use unsafe to convert addr into a []byte.
+	b := unsafe.Slice((*byte)(unsafe.Pointer(addr)), int(info.Segsz))
+	return b, nil
+}
+
+// SysvShmDetach unmaps the shared memory slice returned from SysvShmAttach.
+//
+// It is not safe to use the slice after calling this function.
+func SysvShmDetach(data []byte) error {
+	if len(data) == 0 {
+		return EINVAL
+	}
+
+	return shmdt(uintptr(unsafe.Pointer(&data[0])))
+}
+
+// SysvShmGet returns the Sysv shared memory identifier associated with key.
+// If the IPC_CREAT flag is specified a new segment is created.
+func SysvShmGet(key, size, flag int) (id int, err error) {
+	return shmget(key, size, flag)
+}