Lay Pure out as a core with the parts selected around it

The app model, the tree store and the HTTP host lived in
prototypes/connections among the earlier document runtime, the store was
known only by its format's name, and Vega compiled six Pure sources by path.
Now, as the README's principle has it:

  core/   runtime, flow and the app model (module*.c), with what the core
          asks of storage (state.h, store.h)
  store/  the tree store (PURETRE3, PUREREC1)
  serve/  pure-serve: HTTP host, outbound delivery, JSON in place
  cli/    pure-run, pure-edit-module

A top-level make builds libpure.a (app model and store, for hosts to link)
and the hosts; make check runs the store's and the app model's tests. The
earlier runtime still builds from prototypes/connections against core/ and
store/ (check, check-tree and check-core pass). Design 009 records the rule:
parts by role behind libraries; git repositories split by coupling, so the
store stays here while its contract moves with the core, and Vega stays apart.

1 files changed, 1131 insertions, 0 deletions

diff --git a/store/test-tree-store.c b/store/test-tree-store.c
new file mode 100644
index 0000000..1130acd
--- /dev/null
+++ b/store/test-tree-store.c
@@ -0,0 +1,1131 @@
+#define _POSIX_C_SOURCE 200809L
+#include "store.h"
+#include "state.h"
+#include <assert.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <pthread.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+
+#define CHECK(x) do { if (!(x)) { fprintf(stderr, "%s:%d: %s\n", __FILE__, __LINE__, #x); abort(); } } while (0)
+
+static int fail_stage = -1;
+static int crash;
+static int slow_once; /* the next publication pauses before its data sync */
+static int held_sync;  /* 1: the next publication waits after its head write; 2: it is waiting */
+static void pause_ms(long ms) {
+    struct timespec wait = {ms / 1000, (ms % 1000) * 1000000};
+    nanosleep(&wait, NULL);
+}
+int pure_store_test_fault(PureStoreStage stage) {
+    if (stage == PURE_BEFORE_FILE_SYNC && __atomic_exchange_n(&slow_once, 0, __ATOMIC_SEQ_CST)) pause_ms(100);
+    int one = 1;
+    if (stage == PURE_BEFORE_DIR_SYNC &&
+        __atomic_compare_exchange_n(&held_sync, &one, 2, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST))
+        while (__atomic_load_n(&held_sync, __ATOMIC_SEQ_CST) == 2) pause_ms(1);
+    if ((int)stage != fail_stage) return 0;
+    if (crash) _exit(77);
+    return 1;
+}
+bool pure_tree_test_shape(const char *path, const char *key, unsigned *height,
+                          uint64_t *leaves, uint64_t *small, uint64_t *file_end);
+
+void pure_draft_test_arena(const PureDraft *draft, size_t *nodes, size_t *bytes);
+unsigned long pure_tree_test_publications(void);
+unsigned long pure_tree_test_syncs(void);
+void pure_tree_test_forget(void);
+
+/* The file: head slots in blocks 0 and 1 (sequence at +8, end at +16,
+ * catalog at +24), commits from DATA_START, each a 128-byte record (its head)
+ * and then its bytes. */
+enum { KEYS = 4, CAPACITY = 1 << 20, SLOT_BLOCK = 4096, DATA_START = 8192, RECORD_SIZE = 128 };
+typedef struct { unsigned char *bytes; size_t size; int64_t revision; } Oracle;
+
+static uint32_t random_value(uint32_t *state) {
+    *state ^= *state << 13;
+    *state ^= *state >> 17;
+    *state ^= *state << 5;
+    return *state;
+}
+
+static void expect(const char *path, const char *key, const Oracle *o) {
+    PureStoredView view;
+    CHECK(pure_store_get(path, key, PURE_OBJECT_LIMIT, &view) == PURE_OK);
+    CHECK(view.revision == o->revision && view.body.size == o->size);
+    CHECK(!o->size || !memcmp(view.body.data, o->bytes, o->size));
+    pure_store_release(&view);
+}
+
+static uint64_t file_size(const char *path) {
+    char name[512];
+    snprintf(name, sizeof(name), "%s/pure.tree", path);
+    struct stat info;
+    CHECK(stat(name, &info) == 0);
+    return (uint64_t)info.st_size;
+}
+
+/* Where the newest commit ends. */
+static uint64_t published_end(const char *path, const char *key) {
+    unsigned height;
+    uint64_t leaves, small, end;
+    CHECK(pure_tree_test_shape(path, key, &height, &leaves, &small, &end));
+    return end;
+}
+
+static uint64_t field_at(int fd, uint64_t at) {
+    unsigned char bytes[8];
+    CHECK(pread(fd, bytes, 8, (off_t)at) == 8);
+    uint64_t value = 0;
+    for (unsigned i = 0; i < 8; ++i) value |= (uint64_t)bytes[i] << (8 * i);
+    return value;
+}
+
+static uint64_t slot_field(int fd, unsigned slot, unsigned offset) { return field_at(fd, slot * SLOT_BLOCK + offset); }
+
+/* Where the newest head is: the newer slot's, or the last record after it. */
+static uint64_t newest_head(int fd) {
+    uint64_t at = slot_field(fd, 0, 8) > slot_field(fd, 1, 8) ? 0 : SLOT_BLOCK;
+    for (;;) {
+        uint64_t end = field_at(fd, at + 16);
+        unsigned char magic[8];
+        if (pread(fd, magic, 8, (off_t)end) != 8 || memcmp(magic, "PUREREC1", 8) ||
+            field_at(fd, end + 8) != field_at(fd, at + 8) + 1) return at;
+        at = end;
+    }
+}
+
+static void fill(unsigned char *bytes, size_t size, uint32_t *state) {
+    for (size_t i = 0; i < size; ++i) bytes[i] = (unsigned char)random_value(state);
+}
+
+/* Random edits against a flat oracle, including views held across later
+ * commits and compactions. Every stored node must stay balanced. */
+static void oracle(const char *path) {
+    static const char *keys[KEYS] = {"alpha", "b", "gamma-long_key-0123456789", "z"};
+    Oracle docs[KEYS] = {{0}};
+    unsigned char *insert = malloc(65536);
+    for (unsigned k = 0; k < KEYS; ++k) CHECK((docs[k].bytes = malloc(CAPACITY)));
+    CHECK(insert);
+    uint32_t state = 0x9e3779b9u;
+    PureStoredView held = {0};
+    unsigned char *held_copy = malloc(CAPACITY);
+    size_t held_size = 0;
+    unsigned max_height = 0;
+    size_t max_size = 0, splices = 0;
+    for (unsigned step = 0; step < 6000; ++step) {
+        unsigned k = random_value(&state) % KEYS;
+        Oracle *o = &docs[k];
+        uint32_t kind = random_value(&state) % 100;
+        size_t count = kind < 70 ? random_value(&state) % 24 :
+                       kind < 95 ? random_value(&state) % 6000 : random_value(&state) % 65536;
+        int64_t revision;
+        fill(insert, count, &state);
+        if (kind >= 98 || !o->revision) {
+            CHECK(pure_store_put(path, keys[k], o->revision, (PureSpan){insert, count}, &revision) == PURE_OK);
+            memcpy(o->bytes, insert, count);
+            o->size = count;
+        } else {
+            size_t offset = o->size ? random_value(&state) % (o->size + 1) : 0;
+            size_t remove = o->size - offset ? random_value(&state) % (o->size - offset + 1) : 0;
+            if (random_value(&state) % 24) remove = remove % 64;
+            if (o->size - remove + count > CAPACITY) { count = 0; remove = o->size - offset; }
+            CHECK(pure_store_splice(path, keys[k], o->revision, offset, remove,
+                                    (PureSpan){insert, count}, PURE_OBJECT_LIMIT, &revision) == PURE_OK);
+            memmove(o->bytes + offset + count, o->bytes + offset + remove, o->size - offset - remove);
+            memcpy(o->bytes + offset, insert, count);
+            o->size = o->size - remove + count;
+            ++splices;
+        }
+        if (o->size > max_size) max_size = o->size;
+        CHECK(revision == o->revision + 1);
+        o->revision = revision;
+        expect(path, keys[k], o);
+        unsigned height;
+        uint64_t leaves, small, end;
+        CHECK(pure_tree_test_shape(path, keys[k], &height, &leaves, &small, &end));
+        CHECK(small == 0);
+        if (height > max_height) max_height = height;
+        if (step % 97 == 0) {
+            if (held.mapped_size) {
+                CHECK(held.body.size == held_size && !memcmp(held.body.data, held_copy, held_size));
+                pure_store_release(&held);
+            }
+            CHECK(pure_store_get(path, keys[k], PURE_OBJECT_LIMIT, &held) == PURE_OK);
+            held_size = held.body.size;
+            if (held_size) memcpy(held_copy, held.body.data, held_size);
+        }
+    }
+    if (held.mapped_size) {
+        CHECK(held.body.size == held_size && !memcmp(held.body.data, held_copy, held_size));
+        pure_store_release(&held);
+    }
+    for (unsigned k = 0; k < KEYS; ++k) { expect(path, keys[k], &docs[k]); free(docs[k].bytes); }
+    CHECK(max_height >= 2 && max_height <= 4 && max_size > 262144);
+    printf("{\"oracle_steps\":6000,\"splices\":%zu,\"max_document_bytes\":%zu,\"max_height\":%u}\n",
+           splices, max_size, max_height);
+    free(insert);
+    free(held_copy);
+}
+
+/* A one-byte insert, delete or replacement in a 1 MiB document appends only
+ * its changed leaf and path, not another copy of the document. */
+static void amplification(const char *path) {
+    size_t size = 1048576;
+    unsigned char *bytes = malloc(size + 1);
+    uint32_t state = 7;
+    CHECK(bytes);
+    fill(bytes, size, &state);
+    int64_t revision;
+    CHECK(pure_store_put(path, "large", 0, (PureSpan){bytes, size}, &revision) == PURE_OK);
+    Oracle o = {bytes, size, revision};
+    unsigned char byte = 'Q';
+    const size_t edits[][3] = {{size / 2, 0, 1}, {size / 3, 1, 0}, {size - 1, 1, 1}, {0, 0, 1}};
+    uint64_t worst = 0;
+    for (size_t i = 0; i < sizeof(edits) / sizeof(*edits); ++i) {
+        uint64_t before = published_end(path, "large");
+        size_t offset = edits[i][0], remove = edits[i][1], count = edits[i][2];
+        CHECK(pure_store_splice(path, "large", o.revision, offset, remove, (PureSpan){&byte, count},
+                                PURE_OBJECT_LIMIT, &revision) == PURE_OK);
+        memmove(bytes + offset + count, bytes + offset + remove, o.size - offset - remove);
+        memcpy(bytes + offset, &byte, count);
+        o.size = o.size - remove + count;
+        o.revision = revision;
+        uint64_t after = published_end(path, "large");
+        if (after > before && after - before > worst) worst = after - before;
+        expect(path, "large", &o);
+    }
+    /* Compaction may shrink the file; growth per edit is the claim. */
+    CHECK(worst > 0 && worst < 16384);
+    unsigned height;
+    uint64_t leaves, small, end;
+    CHECK(pure_tree_test_shape(path, "large", &height, &leaves, &small, &end));
+    CHECK(small == 0 && height == 2 && leaves >= 256 && leaves <= 512);
+    printf("{\"one_byte_edit_max_appended_bytes\":%llu,\"height\":%u,\"leaves\":%llu}\n",
+           (unsigned long long)worst, height, (unsigned long long)leaves);
+    free(bytes);
+}
+
+static void faults(const char *path) {
+    unsigned char text[] = "fault-free";
+    int64_t revision;
+    CHECK(pure_store_put(path, "fault", 0, (PureSpan){text, 10}, &revision) == PURE_OK);
+    Oracle o = {text, 10, revision};
+    uint64_t size = file_size(path), end = published_end(path, "fault");
+    for (fail_stage = PURE_AFTER_HEADER; fail_stage <= PURE_BEFORE_RENAME; ++fail_stage) {
+        CHECK(pure_store_splice(path, "fault", o.revision, 1, 3, (PureSpan){text, 5},
+                                PURE_OBJECT_LIMIT, &revision) == PURE_STORE_ERROR);
+        expect(path, "fault", &o);
+        /* The bytes stayed unpublished, in the written zeros after the end. */
+        CHECK(published_end(path, "fault") == end && file_size(path) == size);
+    }
+    fail_stage = PURE_BEFORE_DIR_SYNC;
+    CHECK(pure_store_splice(path, "fault", o.revision, 10, 0, (PureSpan){text, 2},
+                            PURE_OBJECT_LIMIT, &revision) == PURE_UNCERTAIN);
+    fail_stage = -1;
+    unsigned char next[] = "fault-freefa";
+    o = (Oracle){next, 12, o.revision + 1};
+    CHECK(revision == o.revision);
+    expect(path, "fault", &o);
+}
+
+/* A process that dies at each publication stage leaves either the previous
+ * or the next complete version; the next commit overwrites its unpublished
+ * bytes. A head it wrote but did not sync is made durable before the next
+ * writer builds on it. */
+static void crashes(const char *path) {
+    unsigned char text[] = "crash-base";
+    int64_t revision;
+    CHECK(pure_store_put(path, "crash", 0, (PureSpan){text, 10}, &revision) == PURE_OK);
+    Oracle o = {text, 10, revision};
+    for (int stage = PURE_AFTER_HEADER; stage <= PURE_BEFORE_DIR_SYNC; ++stage) {
+        uint64_t before = published_end(path, "crash");
+        pid_t child = fork();
+        CHECK(child >= 0);
+        if (!child) {
+            crash = 1;
+            fail_stage = stage;
+            pure_store_splice(path, "crash", o.revision, 0, 1, (PureSpan){(const unsigned char *)"C", 1},
+                              PURE_OBJECT_LIMIT, &revision);
+            _exit(0);
+        }
+        int status;
+        CHECK(waitpid(child, &status, 0) == child && WIFEXITED(status) && WEXITSTATUS(status) == 77);
+        if (stage == PURE_BEFORE_DIR_SYNC) { text[0] = 'C'; ++o.revision; }
+        expect(path, "crash", &o);
+        uint64_t published = published_end(path, "crash");
+        CHECK(stage == PURE_BEFORE_DIR_SYNC ? published > before : published == before);
+        unsigned long syncs = pure_tree_test_syncs();
+        CHECK(pure_store_splice(path, "crash", o.revision, 10, 0, (PureSpan){(const unsigned char *)"", 0},
+                                PURE_OBJECT_LIMIT, &revision) == PURE_OK);
+        o.revision = revision;
+        expect(path, "crash", &o);
+        CHECK(pure_tree_test_syncs() - syncs == (stage == PURE_BEFORE_DIR_SYNC ? 2u : 1u));
+        CHECK(published_end(path, "crash") > published);
+    }
+}
+
+static void tear(const char *path, uint64_t at) {
+    char name[512];
+    snprintf(name, sizeof(name), "%s/pure.tree", path);
+    int fd = open(name, O_RDWR);
+    unsigned char torn;
+    CHECK(fd >= 0 && pread(fd, &torn, 1, (off_t)at) == 1);
+    torn ^= 0x5a;
+    CHECK(pwrite(fd, &torn, 1, (off_t)at) == 1 && close(fd) == 0);
+}
+
+/* A torn newest record exposes the previous commit to a new process, and the
+ * next writer overwrites that record and the commit's bytes. A torn slot
+ * costs only a longer walk: the other slot's head leads along the records. */
+static void torn_head(const char *path) {
+    unsigned char first[] = "first", second[] = "second";
+    int64_t revision;
+    CHECK(pure_store_put(path, "torn", 0, (PureSpan){first, 5}, &revision) == PURE_OK);
+    Oracle o = {first, 5, revision};
+    uint64_t record = published_end(path, "torn"); /* where the next commit's record goes */
+    CHECK(pure_store_put(path, "torn", o.revision, (PureSpan){second, 6}, &revision) == PURE_OK);
+    tear(path, SLOT_BLOCK + 20);
+    pure_tree_test_forget();
+    expect(path, "torn", &(Oracle){second, 6, revision});
+    tear(path, record + 20);
+    pure_tree_test_forget();
+    expect(path, "torn", &o);
+    CHECK(pure_store_put(path, "torn", o.revision + 1, (PureSpan){first, 1}, &revision) == PURE_CONFLICT);
+    CHECK(pure_store_put(path, "torn", o.revision, (PureSpan){second, 3}, &revision) == PURE_OK);
+    o = (Oracle){second, 3, revision};
+    CHECK(published_end(path, "torn") < record + RECORD_SIZE + 4096); /* it went where the torn one was */
+    pure_tree_test_forget();
+    expect(path, "torn", &o);
+}
+
+/* Commits are found along their records: from a slot's head, which every
+ * CHECKPOINT commits moves on, by a new process too; a damaged record ends
+ * the walk at the commit before it, which the next writer builds on. */
+static void records(const char *path) {
+    int64_t revision;
+    uint64_t ends[41];
+    char text[16];
+    CHECK(pure_store_put(path, "walk", 0, (PureSpan){(const unsigned char *)"0", 1}, &revision) == PURE_OK);
+    for (unsigned i = 1; i <= 40; ++i) {
+        ends[i] = published_end(path, "walk");
+        snprintf(text, sizeof(text), "%u", i);
+        CHECK(pure_store_put(path, "walk", revision, (PureSpan){(const unsigned char *)text, strlen(text)},
+                             &revision) == PURE_OK);
+    }
+    char name[512];
+    snprintf(name, sizeof(name), "%s/pure.tree", path);
+    int fd = open(name, O_RDONLY);
+    CHECK(fd >= 0);
+    uint64_t newest_slot = slot_field(fd, 0, 8) > slot_field(fd, 1, 8) ? slot_field(fd, 0, 8) : slot_field(fd, 1, 8);
+    CHECK(close(fd) == 0);
+    /* 42 commits (the empty file's first): heads in slots at 17 and 33. */
+    CHECK(newest_slot == 33);
+    pure_tree_test_forget();
+    expect(path, "walk", &(Oracle){(unsigned char *)"40", 2, 41});
+    pid_t child = fork();
+    CHECK(child >= 0);
+    if (!child) {
+        pure_tree_test_forget(); /* a process that never saw them */
+        PureStoredView view;
+        _exit(pure_store_get(path, "walk", 16, &view) == PURE_OK && view.body.size == 2 &&
+              !memcmp(view.body.data, "40", 2) && view.revision == 41 ? 0 : 1);
+    }
+    int status;
+    CHECK(waitpid(child, &status, 0) == child && WIFEXITED(status) && WEXITSTATUS(status) == 0);
+    /* Commit 37 ("37", revision 38) has a damaged record: the walk ends at 36. */
+    tear(path, ends[37] + 30);
+    pure_tree_test_forget();
+    expect(path, "walk", &(Oracle){(unsigned char *)"36", 2, 37});
+    CHECK(pure_store_put(path, "walk", 37, (PureSpan){(const unsigned char *)"x", 1}, &revision) == PURE_OK);
+    CHECK(revision == 38 && published_end(path, "walk") < ends[38]);
+    pure_tree_test_forget();
+    expect(path, "walk", &(Oracle){(unsigned char *)"x", 1, 38});
+}
+
+/* A reader's view stays byte-identical while another process commits and
+ * compacts; readers take no lock. */
+static void isolation(const char *path) {
+    size_t size = 300000;
+    unsigned char *bytes = malloc(size);
+    uint32_t state = 99;
+    CHECK(bytes);
+    fill(bytes, size, &state);
+    int64_t revision;
+    CHECK(pure_store_put(path, "shared", 0, (PureSpan){bytes, size}, &revision) == PURE_OK);
+    PureStoredView view;
+    CHECK(pure_store_get(path, "shared", size, &view) == PURE_OK);
+    uint64_t before = file_size(path);
+    pid_t child = fork();
+    CHECK(child >= 0);
+    if (!child) {
+        int64_t at = revision;
+        unsigned char byte = 'x';
+        for (unsigned i = 0; i < 400; ++i)
+            if (pure_store_splice(path, "shared", at, (i * 7919u) % size, 1, (PureSpan){&byte, 1},
+                                  PURE_OBJECT_LIMIT, &at) != PURE_OK) _exit(1);
+        _exit(0);
+    }
+    int status;
+    CHECK(waitpid(child, &status, 0) == child && WIFEXITED(status) && WEXITSTATUS(status) == 0);
+    CHECK(view.revision == revision && view.body.size == size && !memcmp(view.body.data, bytes, size));
+    pure_store_release(&view);
+    PureStoredView latest;
+    CHECK(pure_store_get(path, "shared", size, &latest) == PURE_OK && latest.revision == revision + 400);
+    pure_store_release(&latest);
+    /* About 2 MB of path copies without compaction would exceed this. */
+    CHECK(file_size(path) < before + 3 * 524288);
+    free(bytes);
+}
+
+/* Damaged branch bytes are reported as storage errors, never trusted. */
+static void corruption(const char *path) {
+    unsigned char *bytes = malloc(200000);
+    uint32_t state = 3;
+    CHECK(bytes);
+    fill(bytes, 200000, &state);
+    int64_t revision;
+    CHECK(pure_store_put(path, "damaged", 0, (PureSpan){bytes, 200000}, &revision) == PURE_OK);
+    char name[512];
+    snprintf(name, sizeof(name), "%s/pure.tree", path);
+    uint64_t end = published_end(path, "damaged");
+    int fd = open(name, O_RDWR);
+    CHECK(fd >= 0);
+    unsigned errors = 0;
+    for (unsigned i = 0; i < 3000; ++i) {
+        off_t at = (off_t)(DATA_START + random_value(&state) % (end - DATA_START));
+        unsigned char original, damaged;
+        CHECK(pread(fd, &original, 1, at) == 1);
+        damaged = original ^ (unsigned char)(1u << (random_value(&state) % 8));
+        CHECK(pwrite(fd, &damaged, 1, at) == 1);
+        PureStoredView view;
+        PureResult result = pure_store_get(path, "damaged", PURE_OBJECT_LIMIT, &view);
+        CHECK(result == PURE_OK || result == PURE_STORE_ERROR || result == PURE_NOT_FOUND);
+        if (result == PURE_OK) pure_store_release(&view); else ++errors;
+        CHECK(pwrite(fd, &original, 1, at) == 1);
+    }
+    CHECK(close(fd) == 0 && errors > 0);
+    free(bytes);
+}
+
+static void many_keys(const char *path) {
+    int64_t revision;
+    char key[32];
+    for (unsigned i = 0; i < 1024; ++i) {
+        unsigned id = (i * 617u) % 1024u;
+        snprintf(key, sizeof(key), "doc-%04u", id);
+        CHECK(pure_store_put(path, key, 0, (PureSpan){(const unsigned char *)key, strlen(key)}, &revision) == PURE_OK);
+    }
+    for (unsigned id = 0; id < 1024; ++id) {
+        snprintf(key, sizeof(key), "doc-%04u", id);
+        Oracle o = {(unsigned char *)key, strlen(key), 1};
+        expect(path, key, &o);
+    }
+    PureStoredView view;
+    CHECK(pure_store_get(path, "doc-1024", 64, &view) == PURE_NOT_FOUND);
+    CHECK(pure_store_get(path, "doc-0001", 3, &view) == PURE_BUDGET);
+    CHECK(pure_store_splice(path, "doc-0002", 1, 9, 0, (PureSpan){0}, PURE_OBJECT_LIMIT, &revision) == PURE_LIMIT);
+    CHECK(pure_store_put(path, "doc-0003", 0, (PureSpan){0}, &revision) == PURE_CONFLICT && revision == 1);
+}
+
+/* The newest catalog of a one-key store is one leaf; forge its revision. */
+static void revision_limit(const char *path) {
+    int64_t revision;
+    CHECK(pure_store_put(path, "work", 0, (PureSpan){(const unsigned char *)"w", 1}, &revision) == PURE_OK);
+    char name[512];
+    snprintf(name, sizeof(name), "%s/pure.tree", path);
+    int fd = open(name, O_RDWR);
+    CHECK(fd >= 0);
+    uint64_t catalog = field_at(fd, newest_head(fd) + 24);
+    CHECK(catalog >> 63);
+    const unsigned char maximum[] = {255,255,255,255,255,255,255,127};
+    off_t record = (off_t)(catalog & ((UINT64_C(1) << 62) - 1));
+    CHECK(pwrite(fd, maximum, 8, record + 80) == 8 && close(fd) == 0);
+    /* The forged commit no longer matches its digest; this process wrote it
+     * and does not read it again, a new process would pass over it. */
+    PureStoredView view;
+    CHECK(pure_store_get(path, "work", 1, &view) == PURE_OK && view.revision == INT64_MAX);
+    pure_store_release(&view);
+    CHECK(pure_store_splice(path, "work", INT64_MAX, 0, 0, (PureSpan){0}, PURE_OBJECT_LIMIT, &revision) == PURE_LIMIT);
+}
+
+static bool count_key(void *context, const char *key) {
+    (void)key;
+    ++*(unsigned *)context;
+    return true;
+}
+
+static void keys(const char *path) {
+    unsigned count = 0;
+    CHECK(pure_store_keys(path, count_key, &count) == PURE_OK && count == 0);
+    int64_t revision;
+    const char *names[] = {"m", "a", "zz", "a-b", "A"};
+    for (unsigned i = 0; i < 5; ++i)
+        CHECK(pure_store_put(path, names[i], 0, (PureSpan){0}, &revision) == PURE_OK);
+    CHECK(pure_store_keys(path, count_key, &count) == PURE_OK && count == 5);
+}
+
+typedef struct { unsigned char *out; size_t spans, largest, limit; } Gather;
+
+static bool gather(void *context, PureSpan span) {
+    Gather *g = context;
+    memcpy(g->out, span.data, span.size);
+    g->out += span.size;
+    if (span.size > g->largest) g->largest = span.size;
+    return ++g->spans != g->limit;
+}
+
+static void expect_draft(const PureDraft *draft, const Oracle *o, unsigned char *scratch) {
+    Gather g = {scratch, 0, 0, 0};
+    CHECK(pure_draft_size(draft) == o->size && pure_draft_revision(draft) == o->revision);
+    CHECK(pure_draft_read(draft, 0, o->size, gather, &g) == PURE_OK);
+    CHECK((size_t)(g.out - scratch) == o->size && (!o->size || !memcmp(scratch, o->bytes, o->size)));
+    CHECK(g.largest <= 4096);
+}
+
+static void apply(Oracle *o, size_t offset, size_t remove, const unsigned char *insert, size_t count) {
+    memmove(o->bytes + offset + count, o->bytes + offset + remove, o->size - offset - remove);
+    if (count) memcpy(o->bytes + offset, insert, count);
+    o->size = o->size - remove + count;
+}
+
+/* Edits live only in the draft until commit; each commit continues from the
+ * published version with an empty arena. */
+static void drafts(const char *path) {
+    Oracle o = {malloc(CAPACITY), 0, 0};
+    unsigned char *scratch = malloc(CAPACITY), *insert = malloc(65536);
+    CHECK(o.bytes && scratch && insert);
+    PureDraft *draft;
+    PureStoredView view;
+    CHECK(pure_draft_open(path, "draft", &draft) == PURE_OK);
+    expect_draft(draft, &o, scratch);
+    uint32_t state = 0x1234567u;
+    for (unsigned step = 0; step < 20000; ++step) {
+        uint32_t kind = random_value(&state) % 100;
+        size_t count = kind < 80 ? random_value(&state) % 8 :
+                       kind < 98 ? random_value(&state) % 4000 : random_value(&state) % 65536;
+        size_t offset = o.size ? random_value(&state) % (o.size + 1) : 0;
+        size_t remove = o.size - offset ? random_value(&state) % (o.size - offset + 1) : 0;
+        if (random_value(&state) % 64) remove %= 16;
+        if (o.size - remove + count > CAPACITY) count = 0;
+        fill(insert, count, &state);
+        CHECK(pure_draft_splice(draft, offset, remove, (PureSpan){insert, count}) == PURE_OK);
+        apply(&o, offset, remove, insert, count);
+        if (step % 97 == 0) expect_draft(draft, &o, scratch);
+        if (step % 1000 == 999) {
+            if (o.revision) CHECK(pure_store_get(path, "draft", PURE_OBJECT_LIMIT, &view) == PURE_OK &&
+                                  view.revision == o.revision);
+            if (o.revision) pure_store_release(&view);
+            int64_t revision;
+            CHECK(pure_draft_commit(draft, &revision) == PURE_OK && revision == o.revision + 1);
+            o.revision = revision;
+            expect(path, "draft", &o);
+            expect_draft(draft, &o, scratch);
+            size_t nodes, bytes;
+            pure_draft_test_arena(draft, &nodes, &bytes);
+            CHECK(nodes == 0);
+        }
+    }
+    CHECK(o.size > 100000);
+    Gather g = {scratch, 0, 0, 3};
+    CHECK(pure_draft_read(draft, 0, o.size, gather, &g) == PURE_OK && g.spans == 3);
+    CHECK(pure_draft_splice(draft, o.size + 1, 0, (PureSpan){0}) == PURE_LIMIT);
+    CHECK(pure_draft_splice(draft, 0, o.size + 1, (PureSpan){0}) == PURE_LIMIT);
+    CHECK(pure_draft_read(draft, o.size, 1, gather, &g) == PURE_LIMIT);
+    expect_draft(draft, &o, scratch);
+    pure_draft_close(draft);
+    printf("{\"draft_steps\":20000,\"draft_commits\":%lld,\"draft_bytes\":%zu}\n",
+           (long long)o.revision, o.size);
+    free(o.bytes);
+    free(scratch);
+    free(insert);
+}
+
+/* Long typing and deleting at one place keeps only the live path in memory,
+ * and its commit appends the typed bytes and path, not the document. */
+static void typing(const char *path) {
+    size_t size = 1048576;
+    Oracle o = {malloc(size + 40000), size, 0};
+    unsigned char *scratch = malloc(size + 40000);
+    uint32_t state = 5;
+    CHECK(o.bytes && scratch);
+    fill(o.bytes, size, &state);
+    CHECK(pure_store_put(path, "typed", 0, (PureSpan){o.bytes, size}, &o.revision) == PURE_OK);
+    PureDraft *draft;
+    CHECK(pure_draft_open(path, "typed", &draft) == PURE_OK);
+    size_t cursor = size / 2, nodes, bytes, peak = 0;
+    for (unsigned i = 0; i < 30000; ++i) {
+        unsigned char byte = (unsigned char)('a' + i % 26);
+        if (i % 3 == 2) {
+            CHECK(pure_draft_splice(draft, cursor - 1, 1, (PureSpan){0}) == PURE_OK);
+            apply(&o, --cursor, 1, NULL, 0);
+        } else {
+            CHECK(pure_draft_splice(draft, cursor, 0, (PureSpan){&byte, 1}) == PURE_OK);
+            apply(&o, cursor++, 0, &byte, 1);
+        }
+        pure_draft_test_arena(draft, &nodes, &bytes);
+        if (bytes > peak) peak = bytes;
+    }
+    expect_draft(draft, &o, scratch);
+    /* Reachable: 10,000 net typed bytes, the leaves they landed in and one
+     * path. Unreachable copies are reclaimed past max(reachable, 32 KiB). */
+    CHECK(peak < 2 * (10000 + 4 * 4096 + 2048) + 32768 + 8192);
+    uint64_t before = published_end(path, "typed");
+    int64_t revision;
+    CHECK(pure_draft_commit(draft, &revision) == PURE_OK);
+    o.revision = revision;
+    uint64_t appended = published_end(path, "typed") - before;
+    CHECK(appended < 10000 + 16384);
+    expect(path, "typed", &o);
+    pure_draft_close(draft);
+    printf("{\"typing_keystrokes\":30000,\"peak_arena_bytes\":%zu,\"commit_appended_bytes\":%llu}\n",
+           peak, (unsigned long long)appended);
+    free(o.bytes);
+    free(scratch);
+}
+
+/* Two drafts of one key: the second commit conflicts and keeps its edits. */
+static void draft_conflict(const char *path) {
+    unsigned char scratch[64];
+    int64_t revision;
+    CHECK(pure_store_put(path, "shared", 0, (PureSpan){(const unsigned char *)"base", 4}, &revision) == PURE_OK);
+    PureDraft *first, *second;
+    CHECK(pure_draft_open(path, "shared", &first) == PURE_OK && pure_draft_open(path, "shared", &second) == PURE_OK);
+    CHECK(pure_draft_splice(first, 4, 0, (PureSpan){(const unsigned char *)"-one", 4}) == PURE_OK);
+    CHECK(pure_draft_splice(second, 0, 0, (PureSpan){(const unsigned char *)"two-", 4}) == PURE_OK);
+    CHECK(pure_draft_commit(first, &revision) == PURE_OK && revision == 2);
+    CHECK(pure_draft_commit(second, &revision) == PURE_CONFLICT && revision == 2);
+    Oracle kept = {(unsigned char *)"two-base", 8, 1};
+    expect_draft(second, &kept, scratch);
+    Oracle stored = {(unsigned char *)"base-one", 8, 2};
+    expect(path, "shared", &stored);
+    pure_draft_close(second);
+    CHECK(pure_draft_open(path, "shared", &second) == PURE_OK);
+    expect_draft(second, &stored, scratch);
+    CHECK(pure_store_put(path, "shared", 2, (PureSpan){(const unsigned char *)"x", 1}, &revision) == PURE_OK);
+    CHECK(pure_draft_commit(first, &revision) == PURE_CONFLICT && revision == 3);
+    pure_draft_close(first);
+    pure_draft_close(second);
+}
+
+/* Another key's writes compact the file under an open draft; the draft's
+ * stored extents are copied from its old mapping on commit. */
+static void draft_relocation(const char *path) {
+    unsigned char *big = malloc(300000), scratch[20000];
+    uint32_t state = 11;
+    CHECK(big);
+    fill(big, 300000, &state);
+    Oracle o = {malloc(20000), 12000, 0};
+    CHECK(o.bytes);
+    fill(o.bytes, o.size, &state);
+    CHECK(pure_store_put(path, "kept", 0, (PureSpan){o.bytes, o.size}, &o.revision) == PURE_OK);
+    PureDraft *draft;
+    CHECK(pure_draft_open(path, "kept", &draft) == PURE_OK);
+    CHECK(pure_draft_splice(draft, 6000, 10, (PureSpan){(const unsigned char *)"relocated", 9}) == PURE_OK);
+    apply(&o, 6000, 10, (const unsigned char *)"relocated", 9);
+    char name[512];
+    snprintf(name, sizeof(name), "%s/pure.tree", path);
+    struct stat before, after;
+    CHECK(stat(name, &before) == 0);
+    int64_t revision = 0;
+    for (unsigned i = 0; i < 8; ++i)
+        CHECK(pure_store_put(path, "other", revision, (PureSpan){big, 300000 - i}, &revision) == PURE_OK);
+    CHECK(stat(name, &after) == 0 && after.st_ino != before.st_ino);
+    CHECK(pure_draft_commit(draft, &revision) == PURE_OK && revision == o.revision + 1);
+    o.revision = revision;
+    expect(path, "kept", &o);
+    expect_draft(draft, &o, scratch);
+    Oracle other = {big, 300000 - 7, 8};
+    expect(path, "other", &other);
+    pure_draft_close(draft);
+    free(o.bytes);
+    free(big);
+}
+
+/* A held draft keeps earlier versions readable across later edits. */
+static void draft_versions(const char *path) {
+    static unsigned char bytes[200000], scratch[200000];
+    uint32_t state = 17;
+    fill(bytes, sizeof(bytes), &state);
+    int64_t revision;
+    CHECK(pure_store_put(path, "versioned", 0, (PureSpan){bytes, sizeof(bytes)}, &revision) == PURE_OK);
+    PureDraft *draft;
+    CHECK(pure_draft_open(path, "versioned", &draft) == PURE_OK);
+    pure_draft_hold(draft, true);
+    PureVersion first = pure_draft_version(draft);
+    for (unsigned i = 0; i < 400; ++i) {
+        unsigned char byte = (unsigned char)i;
+        CHECK(pure_draft_splice(draft, (i * 977u) % 150000, 3, (PureSpan){&byte, 1}) == PURE_OK);
+    }
+    Gather g = {scratch, 0, 0, 0};
+    CHECK(pure_draft_read_version(draft, first, 0, sizeof(bytes), gather, &g) == PURE_OK);
+    CHECK((size_t)(g.out - scratch) == sizeof(bytes) && !memcmp(scratch, bytes, sizeof(bytes)));
+    CHECK(pure_draft_size(draft) == sizeof(bytes) - 800);
+    size_t nodes, held_bytes, after;
+    pure_draft_test_arena(draft, &nodes, &held_bytes);
+    pure_draft_hold(draft, false);
+    pure_draft_test_arena(draft, &nodes, &after);
+    CHECK(after < held_bytes);
+    pure_draft_close(draft);
+}
+
+/* A draft without a store: edits, versions, restore and reclamation. */
+static void anonymous_draft(const char *path) {
+    (void)path;
+    Oracle o = {malloc(CAPACITY), 0, 0};
+    unsigned char *scratch = malloc(CAPACITY), insert[3000];
+    PureDraft *draft = pure_draft_new();
+    CHECK(draft && o.bytes && scratch && pure_draft_size(draft) == 0 && pure_draft_revision(draft) == 0);
+    uint32_t state = 42;
+    for (unsigned step = 0; step < 4000; ++step) {
+        size_t count = random_value(&state) % (step % 50 ? 12 : sizeof(insert));
+        size_t offset = o.size ? random_value(&state) % (o.size + 1) : 0;
+        size_t remove = o.size - offset ? random_value(&state) % (o.size - offset + 1) % 32 : 0;
+        fill(insert, count, &state);
+        bool abandon = random_value(&state) % 5 == 0;
+        pure_draft_hold(draft, true);
+        PureVersion before = pure_draft_version(draft);
+        CHECK(pure_draft_splice(draft, offset, remove, (PureSpan){insert, count}) == PURE_OK);
+        if (abandon) pure_draft_restore(draft, before);
+        else apply(&o, offset, remove, insert, count);
+        pure_draft_hold(draft, false);
+        if (step % 37 == 0) expect_draft(draft, &o, scratch);
+    }
+    expect_draft(draft, &o, scratch);
+    int64_t revision;
+    CHECK(pure_draft_commit(draft, &revision) == PURE_INVALID);
+    size_t nodes, bytes;
+    pure_draft_test_arena(draft, &nodes, &bytes);
+    CHECK(bytes < 2 * o.size + 65536);
+    pure_draft_close(draft);
+    free(o.bytes);
+    free(scratch);
+}
+
+/* A failed commit changes neither the store nor the draft. */
+static void draft_faults(const char *path) {
+    unsigned char scratch[64];
+    int64_t revision;
+    CHECK(pure_store_put(path, "faulty", 0, (PureSpan){(const unsigned char *)"stable", 6}, &revision) == PURE_OK);
+    PureDraft *draft;
+    CHECK(pure_draft_open(path, "faulty", &draft) == PURE_OK);
+    CHECK(pure_draft_splice(draft, 6, 0, (PureSpan){(const unsigned char *)"+edit", 5}) == PURE_OK);
+    Oracle stored = {(unsigned char *)"stable", 6, 1}, edited = {(unsigned char *)"stable+edit", 11, 1};
+    uint64_t size = file_size(path);
+    for (fail_stage = PURE_AFTER_HEADER; fail_stage <= PURE_BEFORE_RENAME; ++fail_stage) {
+        CHECK(pure_draft_commit(draft, &revision) == PURE_STORE_ERROR);
+        expect(path, "faulty", &stored);
+        expect_draft(draft, &edited, scratch);
+        CHECK(file_size(path) == size);
+    }
+    fail_stage = PURE_BEFORE_DIR_SYNC;
+    CHECK(pure_draft_commit(draft, &revision) == PURE_UNCERTAIN && revision == 2);
+    fail_stage = -1;
+    expect_draft(draft, &edited, scratch);
+    CHECK(pure_draft_commit(draft, &revision) == PURE_CONFLICT && revision == 2);
+    pure_draft_close(draft);
+    CHECK(pure_draft_open(path, "faulty", &draft) == PURE_OK);
+    edited.revision = 2;
+    expect_draft(draft, &edited, scratch);
+    CHECK(pure_draft_splice(draft, 0, 6, (PureSpan){0}) == PURE_OK);
+    CHECK(pure_draft_commit(draft, &revision) == PURE_OK && revision == 3);
+    Oracle final = {(unsigned char *)"+edit", 5, 3};
+    expect(path, "faulty", &final);
+    pure_draft_close(draft);
+    CHECK(pure_draft_open(path, "bad/key", &draft) == PURE_INVALID && !draft);
+}
+
+static bool list_key(void *context, const char *key) {
+    char *seen = context;
+    strcat(seen, key);
+    strcat(seen, ",");
+    return true;
+}
+
+/* Several drafts publish in one commit: all or none, under process crashes,
+ * faults and a stale draft. Runtime values stay out of the document keys. */
+static void batch(const char *path) {
+    unsigned char scratch[64];
+    int64_t revision, revisions[3];
+    CHECK(pure_store_put(path, "alpha", 0, (PureSpan){(const unsigned char *)"a0", 2}, &revision) == PURE_OK);
+    CHECK(pure_store_put(path, "beta", 0, (PureSpan){(const unsigned char *)"b0", 2}, &revision) == PURE_OK);
+    PureDraft *drafts[3];
+    CHECK(pure_draft_open(path, "alpha", &drafts[0]) == PURE_OK && pure_draft_open(path, "beta", &drafts[1]) == PURE_OK);
+    CHECK(pure_state_open(path, "values", &drafts[2]) == PURE_OK && pure_draft_revision(drafts[2]) == 0);
+    PureDraft *bad;
+    CHECK(pure_state_open(path, "bad.name", &bad) == PURE_INVALID && !bad);
+    CHECK(pure_draft_splice(drafts[0], 2, 0, (PureSpan){(const unsigned char *)"+1", 2}) == PURE_OK);
+    CHECK(pure_draft_splice(drafts[1], 0, 2, (PureSpan){(const unsigned char *)"B", 1}) == PURE_OK);
+    CHECK(pure_draft_splice(drafts[2], 0, 0, (PureSpan){(const unsigned char *)"state", 5}) == PURE_OK);
+    Oracle alpha = {(unsigned char *)"a0", 2, 1}, beta = {(unsigned char *)"b0", 2, 1};
+    Oracle alpha_new = {(unsigned char *)"a0+1", 4, 1}, beta_new = {(unsigned char *)"B", 1, 1};
+    Oracle state_new = {(unsigned char *)"state", 5, 0};
+    /* A process that dies anywhere in the commit leaves all three as before,
+     * or all three published once the head is written. */
+    for (int stage = PURE_AFTER_HEADER; stage <= PURE_BEFORE_DIR_SYNC; ++stage) {
+        pid_t child = fork();
+        CHECK(child >= 0);
+        if (!child) {
+            crash = 1;
+            fail_stage = stage;
+            pure_draft_commit_all(drafts, 3, revisions);
+            _exit(0);
+        }
+        int status;
+        CHECK(waitpid(child, &status, 0) == child && WIFEXITED(status) && WEXITSTATUS(status) == 77);
+        PureDraft *state;
+        CHECK(pure_state_open(path, "values", &state) == PURE_OK);
+        if (stage < PURE_BEFORE_DIR_SYNC) {
+            expect(path, "alpha", &alpha);
+            expect(path, "beta", &beta);
+            CHECK(pure_draft_revision(state) == 0 && pure_draft_size(state) == 0);
+            pure_draft_close(state);
+            continue;
+        }
+        Oracle a = alpha_new, b = beta_new, v = state_new;
+        a.revision = b.revision = 2;
+        v.revision = 1;
+        expect(path, "alpha", &a);
+        expect(path, "beta", &b);
+        expect_draft(state, &v, scratch);
+        pure_draft_close(state);
+        /* Undo the crashed commit's effect for the next checks. */
+        CHECK(pure_store_put(path, "alpha", 2, (PureSpan){(const unsigned char *)"a0", 2}, &revision) == PURE_OK);
+    }
+    /* The same batch in this process is now stale on every key. */
+    CHECK(pure_draft_commit_all(drafts, 3, revisions) == PURE_CONFLICT && revisions[0] == 3);
+    for (unsigned i = 0; i < 3; ++i) pure_draft_close(drafts[i]);
+    CHECK(pure_draft_open(path, "alpha", &drafts[0]) == PURE_OK && pure_draft_open(path, "beta", &drafts[1]) == PURE_OK);
+    CHECK(pure_state_open(path, "values", &drafts[2]) == PURE_OK);
+    CHECK(pure_draft_splice(drafts[0], 0, 2, (PureSpan){(const unsigned char *)"A", 1}) == PURE_OK);
+    CHECK(pure_draft_splice(drafts[1], 1, 0, (PureSpan){(const unsigned char *)"!", 1}) == PURE_OK);
+    CHECK(pure_draft_splice(drafts[2], 5, 0, (PureSpan){(const unsigned char *)"+", 1}) == PURE_OK);
+    alpha = (Oracle){(unsigned char *)"a0", 2, 3};
+    beta = (Oracle){(unsigned char *)"B", 1, 2};
+    uint64_t size = file_size(path);
+    for (fail_stage = PURE_AFTER_HEADER; fail_stage <= PURE_BEFORE_RENAME; ++fail_stage) {
+        CHECK(pure_draft_commit_all(drafts, 3, revisions) == PURE_STORE_ERROR);
+        expect(path, "alpha", &alpha);
+        expect(path, "beta", &beta);
+        CHECK(file_size(path) == size);
+    }
+    fail_stage = -1;
+    /* One stale draft stops the whole batch. */
+    PureDraft *other;
+    CHECK(pure_draft_open(path, "beta", &other) == PURE_OK);
+    CHECK(pure_draft_splice(other, 0, 0, (PureSpan){(const unsigned char *)"x", 1}) == PURE_OK);
+    CHECK(pure_draft_commit(other, &revision) == PURE_OK && revision == 3);
+    pure_draft_close(other);
+    CHECK(pure_draft_commit_all(drafts, 3, revisions) == PURE_CONFLICT && revisions[1] == 3);
+    expect(path, "alpha", &alpha);
+    pure_draft_close(drafts[1]);
+    CHECK(pure_draft_open(path, "beta", &drafts[1]) == PURE_OK);
+    CHECK(pure_draft_splice(drafts[1], 0, 0, (PureSpan){(const unsigned char *)"y", 1}) == PURE_OK);
+    CHECK(pure_draft_commit_all(drafts, 3, revisions) == PURE_OK);
+    CHECK(revisions[0] == 4 && revisions[1] == 4 && revisions[2] == 2);
+    expect(path, "alpha", &(Oracle){(unsigned char *)"A", 1, 4});
+    expect(path, "beta", &(Oracle){(unsigned char *)"yxB", 3, 4});
+    expect_draft(drafts[2], &(Oracle){(unsigned char *)"state+", 6, 2}, scratch);
+    /* Drafts continue from the new revisions. */
+    CHECK(pure_draft_splice(drafts[0], 1, 0, (PureSpan){(const unsigned char *)"z", 1}) == PURE_OK);
+    CHECK(pure_draft_commit_all(drafts, 1, revisions) == PURE_OK && revisions[0] == 5);
+    /* Invalid batches change nothing. */
+    PureDraft *twice[2] = {drafts[0], drafts[0]}, *anonymous = pure_draft_new();
+    CHECK(pure_draft_commit_all(twice, 2, revisions) == PURE_INVALID);
+    PureDraft *mixed[2] = {drafts[1], anonymous};
+    CHECK(pure_draft_commit_all(mixed, 2, revisions) == PURE_INVALID);
+    pure_draft_close(anonymous);
+    for (unsigned i = 0; i < 3; ++i) pure_draft_close(drafts[i]);
+    /* Runtime values are not documents: listings skip them and document
+     * operations refuse their names. */
+    char seen[256] = "";
+    CHECK(pure_store_keys(path, list_key, seen) == PURE_OK && !strcmp(seen, "alpha,beta,"));
+    CHECK(pure_store_put(path, ".values", 0, (PureSpan){(const unsigned char *)"x", 1}, &revision) != PURE_OK);
+    /* Many keys, in no particular order, in one commit. */
+    PureDraft *many[50];
+    int64_t many_revisions[50];
+    char key[16];
+    for (unsigned i = 0; i < 50; ++i) {
+        snprintf(key, sizeof(key), "k%02u", (i * 37) % 50);
+        CHECK((i % 2 ? pure_state_open(path, key, &many[i]) : pure_draft_open(path, key, &many[i])) == PURE_OK);
+        CHECK(pure_draft_splice(many[i], 0, 0, (PureSpan){(const unsigned char *)key, strlen(key)}) == PURE_OK);
+    }
+    CHECK(pure_draft_commit_all(many, 50, many_revisions) == PURE_OK);
+    for (unsigned i = 0; i < 50; ++i) {
+        CHECK(many_revisions[i] == 1);
+        snprintf(key, sizeof(key), "k%02u", (i * 37) % 50);
+        PureDraft *check;
+        CHECK((i % 2 ? pure_state_open(path, key, &check) : pure_draft_open(path, key, &check)) == PURE_OK);
+        expect_draft(check, &(Oracle){(unsigned char *)key, strlen(key), 1}, scratch);
+        pure_draft_close(check);
+        pure_draft_close(many[i]);
+    }
+}
+
+/* A store handle shares one mapping among its drafts, sees commits made by
+ * other writers when a draft opens, follows a compaction that replaced the
+ * file, and maps a batch it committed once. */
+static void store_handle(const char *path) {
+    unsigned char scratch[64];
+    int64_t revision, revisions[3];
+    CHECK(pure_store_put(path, "shared", 0, (PureSpan){(const unsigned char *)"one", 3}, &revision) == PURE_OK);
+    PureStore *store;
+    CHECK(pure_store_open(path, &store) == PURE_OK);
+    PureDraft *a, *b, *state, *bad;
+    CHECK(pure_store_draft(store, "shared", &a) == PURE_OK);
+    expect_draft(a, &(Oracle){(unsigned char *)"one", 3, 1}, scratch);
+    CHECK(pure_store_draft(store, "bad.key", &bad) == PURE_INVALID && !bad);
+    /* Another writer commits: the next draft sees it, the open one keeps its version. */
+    CHECK(pure_store_put(path, "shared", 1, (PureSpan){(const unsigned char *)"two", 3}, &revision) == PURE_OK);
+    CHECK(pure_store_draft(store, "shared", &b) == PURE_OK);
+    expect_draft(b, &(Oracle){(unsigned char *)"two", 3, 2}, scratch);
+    expect_draft(a, &(Oracle){(unsigned char *)"one", 3, 1}, scratch);
+    CHECK(pure_draft_splice(a, 3, 0, (PureSpan){(const unsigned char *)"!", 1}) == PURE_OK);
+    CHECK(pure_draft_commit(a, &revision) == PURE_CONFLICT && revision == 2);
+    pure_draft_close(a);
+    /* A batch of handle drafts, a runtime value among them. */
+    CHECK(pure_store_state(store, "values", &state) == PURE_OK && pure_draft_revision(state) == 0);
+    CHECK(pure_store_draft(store, "other", &a) == PURE_OK);
+    CHECK(pure_draft_splice(b, 3, 0, (PureSpan){(const unsigned char *)"+", 1}) == PURE_OK);
+    CHECK(pure_draft_splice(state, 0, 0, (PureSpan){(const unsigned char *)"v", 1}) == PURE_OK);
+    CHECK(pure_draft_splice(a, 0, 0, (PureSpan){(const unsigned char *)"o", 1}) == PURE_OK);
+    PureDraft *batch[3] = {b, state, a};
+    CHECK(pure_draft_commit_all(batch, 3, revisions) == PURE_OK && revisions[0] == 3 && revisions[1] == 1);
+    expect(path, "shared", &(Oracle){(unsigned char *)"two+", 4, 3});
+    expect_draft(state, &(Oracle){(unsigned char *)"v", 1, 1}, scratch);
+    /* Other writers grow the file past compaction: it is replaced under the handle. */
+    unsigned char *big = malloc(100000);
+    uint32_t seed = 5;
+    CHECK(big);
+    fill(big, 100000, &seed);
+    int64_t filler = 0;
+    char name[512];
+    struct stat before, replaced;
+    snprintf(name, sizeof(name), "%s/pure.tree", path);
+    CHECK(stat(name, &before) == 0);
+    for (int i = 0; i < 8; ++i) CHECK(pure_store_put(path, "filler", filler, (PureSpan){big, 100000}, &filler) == PURE_OK);
+    CHECK(stat(name, &replaced) == 0 && replaced.st_ino != before.st_ino);
+    free(big);
+    PureDraft *after;
+    CHECK(pure_store_draft(store, "shared", &after) == PURE_OK);
+    expect_draft(after, &(Oracle){(unsigned char *)"two+", 4, 3}, scratch);
+    /* Drafts of the old file still read and commit (their extents are copied). */
+    expect_draft(b, &(Oracle){(unsigned char *)"two+", 4, 3}, scratch);
+    CHECK(pure_draft_splice(b, 0, 0, (PureSpan){(const unsigned char *)">", 1}) == PURE_OK);
+    CHECK(pure_draft_commit(b, &revision) == PURE_OK && revision == 4);
+    expect(path, "shared", &(Oracle){(unsigned char *)">two+", 5, 4});
+    pure_draft_close(after);
+    pure_draft_close(a);
+    pure_draft_close(b);
+    pure_draft_close(state);
+    pure_store_close(store);
+}
+
+/* Threads of one process commit through their own handles at once: none is
+ * refused as busy, every commit lands, and edits of one shared key conflict
+ * instead of overwriting each other. */
+typedef struct { const char *path; unsigned number, conflicts; } Committer;
+
+static void *commit_many(void *context) {
+    Committer *c = context;
+    PureStore *store;
+    CHECK(pure_store_open(c->path, &store) == PURE_OK);
+    char key[16];
+    snprintf(key, sizeof(key), "t%u", c->number);
+    for (unsigned i = 0; i < 40; ++i) {
+        PureDraft *own, *shared;
+        int64_t revisions[2];
+        CHECK(pure_store_draft(store, key, &own) == PURE_OK && pure_store_draft(store, "shared", &shared) == PURE_OK);
+        CHECK(pure_draft_splice(own, pure_draft_size(own), 0, (PureSpan){(const unsigned char *)"x", 1}) == PURE_OK);
+        CHECK(pure_draft_splice(shared, pure_draft_size(shared), 0, (PureSpan){(const unsigned char *)"y", 1}) == PURE_OK);
+        PureDraft *batch[2] = {own, shared};
+        PureResult result = pure_draft_commit_all(batch, 2, revisions);
+        CHECK(result == PURE_OK || result == PURE_CONFLICT);
+        if (result == PURE_CONFLICT) {
+            ++c->conflicts;
+            CHECK(pure_draft_commit(own, &revisions[0]) == PURE_OK);
+        }
+        pure_draft_close(own);
+        pure_draft_close(shared);
+    }
+    pure_store_close(store);
+    return NULL;
+}
+
+static void threads(const char *path) {
+    pthread_t thread[4];
+    Committer committer[4];
+    for (unsigned i = 0; i < 4; ++i) {
+        committer[i] = (Committer){path, i, 0};
+        CHECK(pthread_create(&thread[i], NULL, commit_many, &committer[i]) == 0);
+    }
+    unsigned conflicts = 0;
+    for (unsigned i = 0; i < 4; ++i) {
+        CHECK(pthread_join(thread[i], NULL) == 0);
+        conflicts += committer[i].conflicts;
+    }
+    PureStoredView view;
+    char key[16];
+    for (unsigned i = 0; i < 4; ++i) {
+        snprintf(key, sizeof(key), "t%u", i);
+        CHECK(pure_store_get(path, key, PURE_OBJECT_LIMIT, &view) == PURE_OK && view.body.size == 40 && view.revision == 40);
+        pure_store_release(&view);
+    }
+    CHECK(pure_store_get(path, "shared", PURE_OBJECT_LIMIT, &view) == PURE_OK);
+    CHECK(view.body.size == 160 - conflicts && view.revision == (int64_t)(160 - conflicts));
+    pure_store_release(&view);
+}
+
+/* Commits that arrive while another is being published share the next
+ * publication: one head for all of them. */
+typedef struct { const char *path; unsigned number; PureResult result; } Single;
+
+static void *commit_one(void *context) {
+    Single *s = context;
+    PureStore *store;
+    PureDraft *draft;
+    char key[16];
+    int64_t revision;
+    snprintf(key, sizeof(key), "g%u", s->number);
+    CHECK(pure_store_open(s->path, &store) == PURE_OK && pure_store_draft(store, key, &draft) == PURE_OK);
+    CHECK(pure_draft_splice(draft, 0, 0, (PureSpan){(const unsigned char *)key, strlen(key)}) == PURE_OK);
+    s->result = pure_draft_commit(draft, &revision);
+    CHECK(s->result != PURE_OK || revision == 1);
+    pure_draft_close(draft);
+    pure_store_close(store);
+    return NULL;
+}
+
+static void grouped(const char *path) {
+    pthread_t thread[5];
+    Single single[5];
+    unsigned long before = pure_tree_test_publications();
+    __atomic_store_n(&slow_once, 1, __ATOMIC_SEQ_CST);
+    for (unsigned i = 0; i < 5; ++i) {
+        single[i] = (Single){path, i, PURE_INVALID};
+        CHECK(pthread_create(&thread[i], NULL, commit_one, &single[i]) == 0);
+        if (!i) pause_ms(20); /* the first is now publishing, slowly */
+    }
+    for (unsigned i = 0; i < 5; ++i) CHECK(pthread_join(thread[i], NULL) == 0 && single[i].result == PURE_OK);
+    CHECK(pure_tree_test_publications() - before == 2);
+    char key[16];
+    for (unsigned i = 0; i < 5; ++i) {
+        snprintf(key, sizeof(key), "g%u", i);
+        expect(path, key, &(Oracle){(unsigned char *)key, strlen(key), 1});
+    }
+}
+
+/* A crash during a commit's only sync can leave its head on the device
+ * without all of its bytes. A process that starts after it passes over that
+ * head to the previous commit, and the next writer overwrites both. */
+static void lost_commit(const char *path) {
+    unsigned char first[] = "first", second[] = "second";
+    int64_t revision;
+    CHECK(pure_store_put(path, "lost", 0, (PureSpan){first, 5}, &revision) == PURE_OK);
+    Oracle o = {first, 5, revision};
+    uint64_t start = published_end(path, "lost");
+    CHECK(pure_store_put(path, "lost", o.revision, (PureSpan){second, 6}, &revision) == PURE_OK);
+    uint64_t end = published_end(path, "lost");
+    char name[512];
+    snprintf(name, sizeof(name), "%s/pure.tree", path);
+    int fd = open(name, O_RDWR);
+    off_t at = (off_t)(start + (end - start) / 2);
+    unsigned char byte;
+    CHECK(fd >= 0 && pread(fd, &byte, 1, at) == 1);
+    byte ^= 0xff;
+    CHECK(pwrite(fd, &byte, 1, at) == 1 && close(fd) == 0);
+    pure_tree_test_forget();
+    expect(path, "lost", &o);
+    PureStore *store;
+    PureDraft *draft;
+    CHECK(pure_store_open(path, &store) == PURE_OK && pure_store_draft(store, "lost", &draft) == PURE_OK);
+    CHECK(pure_draft_revision(draft) == o.revision);
+    pure_draft_close(draft);
+    CHECK(pure_store_put(path, "lost", o.revision + 1, (PureSpan){first, 1}, &revision) == PURE_CONFLICT);
+    CHECK(pure_store_put(path, "lost", o.revision, (PureSpan){second, 3}, &revision) == PURE_OK);
+    o = (Oracle){second, 3, revision};
+    CHECK(published_end(path, "lost") < end); /* it started where the lost commit did */
+    CHECK(pure_store_draft(store, "lost", &draft) == PURE_OK && pure_draft_revision(draft) == o.revision);
+    pure_draft_close(draft);
+    pure_store_close(store);
+    pure_tree_test_forget();
+    expect(path, "lost", &o);
+}
+
+/* While a commit's sync is pending, this process keeps reading the previous
+ * version: a crash could still take the new one back. */
+static void *commit_held(void *context) {
+    int64_t revision;
+    CHECK(pure_store_put(context, "pending", 1, (PureSpan){(const unsigned char *)"new", 3}, &revision) == PURE_OK);
+    return NULL;
+}
+
+static void pending_head(const char *path) {
+    int64_t revision;
+    CHECK(pure_store_put(path, "pending", 0, (PureSpan){(const unsigned char *)"old", 3}, &revision) == PURE_OK);
+    PureStore *store;
+    PureDraft *draft;
+    CHECK(pure_store_open(path, &store) == PURE_OK);
+    __atomic_store_n(&held_sync, 1, __ATOMIC_SEQ_CST);
+    pthread_t writer;
+    CHECK(pthread_create(&writer, NULL, commit_held, (void *)path) == 0);
+    while (__atomic_load_n(&held_sync, __ATOMIC_SEQ_CST) != 2) pause_ms(1);
+    CHECK(pure_store_draft(store, "pending", &draft) == PURE_OK && pure_draft_revision(draft) == 1);
+    pure_draft_close(draft);
+    expect(path, "pending", &(Oracle){(unsigned char *)"old", 3, 1});
+    __atomic_store_n(&held_sync, 0, __ATOMIC_SEQ_CST);
+    CHECK(pthread_join(writer, NULL) == 0);
+    CHECK(pure_store_draft(store, "pending", &draft) == PURE_OK && pure_draft_revision(draft) == 2);
+    pure_draft_close(draft);
+    pure_store_close(store);
+    expect(path, "pending", &(Oracle){(unsigned char *)"new", 3, 2});
+}
+
+/* A commit costs one sync, and commits into the written zeros after the end
+ * leave the file size alone (no journal commit for a new size). */
+static void one_sync(const char *path) {
+    int64_t revision;
+    CHECK(pure_store_put(path, "sync", 0, (PureSpan){(const unsigned char *)"0", 1}, &revision) == PURE_OK);
+    uint64_t size = file_size(path);
+    unsigned long syncs = pure_tree_test_syncs();
+    for (unsigned i = 0; i < 20; ++i)
+        CHECK(pure_store_put(path, "sync", revision, (PureSpan){(const unsigned char *)"x", 1}, &revision) == PURE_OK);
+    CHECK(pure_tree_test_syncs() - syncs == 20 && file_size(path) == size);
+}
+
+static void clean(const char *path) {
+    DIR *entries = opendir(path);
+    CHECK(entries);
+    struct dirent *entry;
+    while ((entry = readdir(entries))) {
+        if (!strcmp(entry->d_name, ".") || !strcmp(entry->d_name, "..")) continue;
+        CHECK(strncmp(entry->d_name, ".pending-", 9));
+        CHECK(unlinkat(dirfd(entries), entry->d_name, 0) == 0);
+    }
+    CHECK(closedir(entries) == 0 && rmdir(path) == 0);
+}
+
+int main(void) {
+    void (*checks[])(const char *) = {oracle, amplification, faults, crashes, torn_head,
+                                      isolation, corruption, many_keys, revision_limit, keys,
+                                      drafts, typing, draft_conflict, draft_relocation, draft_faults,
+                                      draft_versions, anonymous_draft, batch, store_handle, threads, grouped,
+                                      lost_commit, pending_head, one_sync, records};
+    for (size_t i = 0; i < sizeof(checks) / sizeof(*checks); ++i) {
+        char path[] = "/tmp/pure-tree-check-XXXXXX";
+        CHECK(mkdtemp(path) && pure_store_init(path) == PURE_OK);
+        checks[i](path);
+        CHECK(pure_store_init(path) == PURE_OK);
+        clean(path);
+    }
+    puts("{\"tree_store\":\"random-oracle-balance-held-views-one-byte-amplification-faults-"
+         "process-crash-torn-head-lockless-isolation-compaction-corruption-1024-keys-revision-limit-key-listing-"
+         "draft-oracle-typing-arena-conflict-relocation-commit-faults-held-versions-anonymous-"
+         "atomic-batch-runtime-keys-store-handle-threads-group-commit-lost-commit-pending-head-one-sync-records\"}");
+    return 0;
+}