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[#86] Sync → Refuse to overwrite local edits made mid sync #111

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Merged
revett merged 2 commits into from
Jul 21, 2026
Merged

[#86] Sync → Refuse to overwrite local edits made mid sync #111

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fe86b6c
Fix issue
revett Jul 21, 2026
ea45c55
Address
revett Jul 21, 2026
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177 changes: 168 additions & 9 deletions src/sync/execute.test.ts
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Original file line number Diff line number Diff line change
@@ -1,16 +1,24 @@
import assert from "node:assert/strict";
import { test } from "node:test";
import { hashBytes } from "../vault/vault.ts";
import { executeSyncPlan } from "./execute.ts";
import { fakeLocalWriter, fakeReader, fakeStorage } from "./fake.ts";
import { empty, fakeLocalWriter, fakeReader, fakeStorage, file, snapshot } from "./fake.ts";
import { conflictCopyPath, type SyncAction } from "./plan.ts";

// hashOf returns the real content hash of text, for building local snapshots whose entries
// executeSyncPlan's drift check can verify against a fake reader's live bytes.
async function hashOf(text: string): Promise<string> {
return hashBytes(new TextEncoder().encode(text));
}

test("executeSyncPlan: push reads the local file and puts it remotely", async () => {
const reader = fakeReader({ "a.md": "hello" });
const { writer, files } = fakeLocalWriter();
const { storage, objects } = fakeStorage();

const failures = await executeSyncPlan(
[{ kind: "push", path: "a.md" }],
empty,
reader,
writer,
storage,
Expand All @@ -27,7 +35,7 @@ test("executeSyncPlan: pushDelete removes the remote object", async () => {
const { writer } = fakeLocalWriter();
const { storage, objects } = fakeStorage({ "a.md": "hello" });

await executeSyncPlan([{ kind: "pushDelete", path: "a.md" }], reader, writer, storage, 1);
await executeSyncPlan([{ kind: "pushDelete", path: "a.md" }], empty, reader, writer, storage, 1);

assert.equal(objects.has("a.md"), false);
});
Expand All @@ -39,6 +47,7 @@ test("executeSyncPlan: pull fetches the remote object and writes it locally", as

const failures = await executeSyncPlan(
[{ kind: "pull", path: "a.md" }],
empty,
reader,
writer,
storage,
Expand All @@ -49,17 +58,138 @@ test("executeSyncPlan: pull fetches the remote object and writes it locally", as
assert.equal(files.get("a.md"), "hello");
});

test("executeSyncPlan: pullDelete removes the local file", async () => {
const reader = fakeReader({});
test("executeSyncPlan: pull overwrites a local file that still matches the snapshot", async () => {
const reader = fakeReader({ "a.md": "unchanged" });
const { writer, files } = fakeLocalWriter();
files.set("a.md", "unchanged");
const local = snapshot(file("a.md", await hashOf("unchanged")));
const { storage } = fakeStorage({ "a.md": "remote edit" });

const failures = await executeSyncPlan(
[{ kind: "pull", path: "a.md" }],
local,
reader,
writer,
storage,
1,
);

assert.deepEqual(failures, []);
assert.equal(files.get("a.md"), "remote edit");
});

test("executeSyncPlan: pull onto a file edited after the snapshot is refused and the edit survives", async () => {
// Reproduces #86. The pull was planned from a snapshot in which a.md was unchanged, but the
// user edited it before the plan reached this action. Overwriting it now would silently discard
// that edit, so the action must fail instead (the next sync replans it as a conflict) and the
// rest of the plan must still run.
const reader = fakeReader({ "a.md": "edited after snapshot" });
const { writer, files } = fakeLocalWriter();
files.set("a.md", "edited after snapshot");
const local = snapshot(file("a.md", await hashOf("as snapshotted")));
const { storage } = fakeStorage({ "a.md": "remote edit", "b.md": "remote b" });

const actions: SyncAction[] = [
{ kind: "pull", path: "a.md" },
{ kind: "pull", path: "b.md" },
];
const failures = await executeSyncPlan(actions, local, reader, writer, storage, 1);

assert.deepEqual(failures, [
{ path: "a.md", message: "changed locally mid sync; sync again to reconcile" },
]);
assert.equal(files.get("a.md"), "edited after snapshot");
// The following action still ran.
assert.equal(files.get("b.md"), "remote b");
});

test("executeSyncPlan: pull onto a file created after the snapshot is refused", async () => {
// The snapshot saw nothing at this path (the pull was planned for a remote-only file), but the
// user created a file there before the plan reached this action. Writing the remote version
// over it would discard a file the plan never knew existed.
const reader = fakeReader({ "a.md": "created after snapshot" });
const { writer, files } = fakeLocalWriter();
files.set("a.md", "created after snapshot");
const { storage } = fakeStorage({ "a.md": "remote edit" });

const failures = await executeSyncPlan(
[{ kind: "pull", path: "a.md" }],
empty,
reader,
writer,
storage,
1,
);

assert.deepEqual(failures, [
{ path: "a.md", message: "changed locally mid sync; sync again to reconcile" },
]);
assert.equal(files.get("a.md"), "created after snapshot");
});

test("executeSyncPlan: pullDelete removes a local file that still matches the snapshot", async () => {
const reader = fakeReader({ "a.md": "hello" });
const { writer, files } = fakeLocalWriter();
files.set("a.md", "hello");
const local = snapshot(file("a.md", await hashOf("hello")));
const { storage } = fakeStorage();

await executeSyncPlan([{ kind: "pullDelete", path: "a.md" }], reader, writer, storage, 1);
await executeSyncPlan([{ kind: "pullDelete", path: "a.md" }], local, reader, writer, storage, 1);

assert.equal(files.has("a.md"), false);
});

test("executeSyncPlan: pullDelete of a file edited after the snapshot is refused and the edit survives", async () => {
// Reproduces #86 for the delete side: the remote deletion was planned against a snapshot in
// which a.md was unchanged, but the user edited it in the window since. Deleting it now would
// silently discard the edit; the next sync replans this as a conflict instead.
const reader = fakeReader({ "a.md": "edited after snapshot" });
const { writer, files } = fakeLocalWriter();
files.set("a.md", "edited after snapshot");
const local = snapshot(file("a.md", await hashOf("as snapshotted")));
const { storage } = fakeStorage();

const failures = await executeSyncPlan(
[{ kind: "pullDelete", path: "a.md" }],
local,
reader,
writer,
storage,
1,
);

assert.deepEqual(failures, [
{ path: "a.md", message: "changed locally mid sync; sync again to reconcile" },
]);
assert.equal(files.get("a.md"), "edited after snapshot");
});

test("executeSyncPlan: pullDelete of a file that exists but cannot be read is refused, never treated as absent", async () => {
// A read failing on a file that is still present (a permission error, say) must not read as
// "nothing to discard": the delete could succeed against content the drift check never
// verified. The action must fail with the read's own error and leave the file alone.
const reader = fakeReader({ "a.md": "hello" });
reader.readFile = async () => {
throw new Error("EACCES: permission denied");
};
const { writer, files } = fakeLocalWriter();
files.set("a.md", "hello");
const local = snapshot(file("a.md", await hashOf("hello")));
const { storage } = fakeStorage();

const failures = await executeSyncPlan(
[{ kind: "pullDelete", path: "a.md" }],
local,
reader,
writer,
storage,
1,
);

assert.deepEqual(failures, [{ path: "a.md", message: "EACCES: permission denied" }]);
assert.equal(files.get("a.md"), "hello");
});

test("executeSyncPlan: a conflict renames the local copy, pushes it to storage, and pulls the remote version clean", async () => {
const reader = fakeReader({ "a.md": "local edit" });
const { writer, files } = fakeLocalWriter();
Expand All @@ -69,6 +199,7 @@ test("executeSyncPlan: a conflict renames the local copy, pushes it to storage,

const failures = await executeSyncPlan(
[{ kind: "conflict", path: "a.md", deletedSide: "none" }],
empty,
reader,
writer,
storage,
Expand All @@ -92,6 +223,7 @@ test("executeSyncPlan: a conflict with nothing local to preserve just pulls the

const failures = await executeSyncPlan(
[{ kind: "conflict", path: "a.md", deletedSide: "local" }],
empty,
reader,
writer,
storage,
Expand All @@ -103,6 +235,31 @@ test("executeSyncPlan: a conflict with nothing local to preserve just pulls the
assert.equal(files.has(conflictCopyPath("a.md", now)), false);
});

test("executeSyncPlan: a conflict restore onto a path recreated after the snapshot is refused", async () => {
// The snapshot saw this path as locally deleted, so the plan decided the remote edit could be
// restored with nothing to preserve. The user then recreated the file before the plan reached
// this action; overwriting it now would discard content the plan never saw (#86).
const reader = fakeReader({ "a.md": "recreated after snapshot" });
const { writer, files } = fakeLocalWriter();
files.set("a.md", "recreated after snapshot");
const { storage } = fakeStorage({ "a.md": "remote edit" });
const now = Date.parse("2026-07-14T10:00:00.000Z");

const failures = await executeSyncPlan(
[{ kind: "conflict", path: "a.md", deletedSide: "local" }],
empty,
reader,
writer,
storage,
now,
);

assert.deepEqual(failures, [
{ path: "a.md", message: "changed locally mid sync; sync again to reconcile" },
]);
assert.equal(files.get("a.md"), "recreated after snapshot");
});

test("executeSyncPlan: a conflict with nothing remote to pull preserves the local edit as a copy and reports no failure", async () => {
const reader = fakeReader({ "a.md": "local edit" });
const { writer, files } = fakeLocalWriter();
Expand All @@ -112,6 +269,7 @@ test("executeSyncPlan: a conflict with nothing remote to pull preserves the loca

const failures = await executeSyncPlan(
[{ kind: "conflict", path: "a.md", deletedSide: "remote" }],
empty,
reader,
writer,
storage,
Expand All @@ -136,7 +294,7 @@ test("executeSyncPlan: a push whose local file vanished is reported and doesn't
{ kind: "push", path: "a.md" },
{ kind: "push", path: "b.md" },
];
const failures = await executeSyncPlan(actions, reader, writer, storage, 1);
const failures = await executeSyncPlan(actions, empty, reader, writer, storage, 1);

assert.deepEqual(failures, [{ path: "a.md", message: "no such file: a.md" }]);
assert.equal(objects.get("b.md"), "world");
Expand All @@ -156,7 +314,7 @@ test("executeSyncPlan: a conflict whose local file vanished is reported, nothing
{ kind: "conflict", path: "a.md", deletedSide: "none" },
{ kind: "push", path: "b.md" },
];
const failures = await executeSyncPlan(actions, reader, writer, storage, now);
const failures = await executeSyncPlan(actions, empty, reader, writer, storage, now);

assert.deepEqual(failures, [{ path: "a.md", message: "no such file: a.md" }]);
// No conflict copy was created locally or remotely from a file that wasn't there to preserve.
Expand All @@ -182,7 +340,7 @@ test("executeSyncPlan: a failed push is reported and doesn't stop the rest of th
{ kind: "push", path: "a.md" },
{ kind: "push", path: "b.md" },
];
const failures = await executeSyncPlan(actions, reader, writer, storage, 1);
const failures = await executeSyncPlan(actions, empty, reader, writer, storage, 1);

assert.deepEqual(failures, [{ path: "a.md", message: "Storage rejected the write (500)" }]);
assert.equal(objects.get("b.md"), "world");
Expand All @@ -206,7 +364,7 @@ test("executeSyncPlan: a pull whose local write throws is reported and doesn't s
{ kind: "pull", path: "a.md" },
{ kind: "pull", path: "b.md" },
];
const failures = await executeSyncPlan(actions, reader, writer, storage, 1);
const failures = await executeSyncPlan(actions, empty, reader, writer, storage, 1);

assert.deepEqual(failures, [{ path: "a.md", message: "EACCES: permission denied" }]);
assert.equal(files.get("b.md"), "pulled");
Expand All @@ -227,6 +385,7 @@ test("executeSyncPlan: a conflict whose rename throws is reported and the local

const failures = await executeSyncPlan(
[{ kind: "conflict", path: "a.md", deletedSide: "none" }],
empty,
reader,
writer,
storage,
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