diff --git a/specifier-prompt.md b/specifier-prompt.md
index ca8271e..35c08be 100644
--- a/specifier-prompt.md
+++ b/specifier-prompt.md
@@ -386,7 +386,16 @@ that a single user-facing feature may require specs in more than one component.
     store and falls back to an optional externally loaded URL (e.g. from
     memo-db). Spec rendering features against that seam (image shown with the
     right `src`, no `<img>` when unset) rather than against the DOM. Spec:
-    `psf-memo-client/specs/account-avatar-display.feature`.
+23. **Upper-bound performance assertions can survive Gherkin mutation.**
+    A step like `the postChildren store was read at most <max_entries> entries`
+    only fails when the measured reads exceed the bound, so mutating the example
+    value upward (e.g. `1 -> 3`) can never fail and survives. The
+    thread-query-performance soft mutation run killed 6 of 8 and left both
+    `max_entries` upper-bound mutations alive. Treat these as intrinsic
+    equivalents (documented in `docs/reviews/thread-query-bounds-summary.md`),
+    not implementation gaps; prefer exact counts or independently-tied fixture
+    data when a bound must itself be mutatable. Spec:
+    `psf-memo-db/specs/thread-query-performance.feature`.
 
 ---
 
@@ -424,13 +433,13 @@ At the end of each session, update this file:
 - Note the current `master` HEAD commit.
 - State the next feature to work on.
 
-Current `master` HEAD: `5afaa64` (merged architect's account-avatar-display job —
-the `/account` page now renders the avatar image when an avatar URL is set,
-via a pure `AvatarImage` component shared by the browser build and the Node
-acceptance adapter, with `AccountPage` display helpers
-`getDisplayAvatarUrl`/`hasAvatarImage`/`getAvatarImageUrl` as the testable seam.
-Verified client unit (298) + property (43) + acceptance (all 25 suites) +
-lint + build all passing).
+Current `master` HEAD: `c8ceb82` (merged architect's thread-query-bounds job —
+`GET /posts/:txid/thread` now counts likes only for the thread's txids via
+`countLikesForTxids` and prefix-scans `postChildren` per parent through a new
+`PostQuery.listChildTxids` seam, so its work is proportional to the thread
+rather than the database. Spec:
+`psf-memo-db/specs/thread-query-performance.feature`. Verified psf-memo-db unit
+(357) + property (44) + acceptance (all 11 suites) + lint all passing).
 Next action: **TBD** — current direction is front-end improvements to
 `psf-memo-client` (UI/UX polish, accessibility, performance, responsiveness,
 state handling, error surfacing). See `specs/feature-backlog.md`.
diff --git a/specs/feature-backlog.md b/specs/feature-backlog.md
index f5f6504..ca19ec2 100644
--- a/specs/feature-backlog.md
+++ b/specs/feature-backlog.md
@@ -31,6 +31,14 @@ focus is **front-end improvements** to `psf-memo-client` (the React SPA).
 
 ## Recently completed
 
+- **Thread query performance (2026-09-15):** `GET /posts/:txid/thread` now does
+  work proportional to the thread instead of the whole database. Like counts are
+  computed only for the thread's txids via `countLikesForTxids` (the global
+  `buildLikeCountMap` was removed), and child lookups prefix-scan `postChildren`
+  per parent through a new `PostQuery.listChildTxids` seam instead of walking the
+  whole store once per node. Spec:
+  `psf-memo-db/specs/thread-query-performance.feature`. Merged to `master` at
+  `c8ceb82`.
 - **Account avatar display (2026-09-05):** the `/account` page now renders the
   avatar image when an avatar URL is set, instead of only showing the URL as
   text. A pure `AvatarImage` component (`src/components/account/avatar-image.js`,
@@ -157,35 +165,10 @@ Reference: https://memo.sv/protocol (Wayback snapshot 2025-12-15)
 
 ---
 
-## Next up: Thread query performance (psf-memo-db)
+## Next up: TBD
 
-`GET /posts/:txid/thread` is slow because `get-post-thread.js` does work
-proportional to the whole database instead of the requested thread. Two
-independent parts, one feature spec:
-
-- **Part A — like counts scoped to the thread.** `execute()` calls
-  `buildLikeCountMap()`, which iterates every `postLikes` entry and loads one
-  post per like. Build the thread first, then count likes for the thread's
-  txids via the existing `countLikesForTxids`.
-- **Part B — child loading uses the parent index.** `loadChildTxids()`
-  iterates every `postChildren` entry once per thread node. Prefix-scan
-  `parentTxid:childTxid` (as `countRepliesForTxids` already does) instead.
-
-Spec: `psf-memo-db/specs/thread-query-performance.feature`. Affected
-component: D (`psf-memo-db`). No client, indexer, or protocol changes.
-
-Thread shape, reply ordering, and per-node `likeCount` remain specified by
-`psf-memo-db/specs/like-counts.feature` (scenario 3). `buildLikeCountMap`
-still has unit/property coverage; the coder should update it if the method is
-removed.
-
----
-
-## Previous: account avatar display — DONE (2026-09-05)
-
-The `/account` page now renders the avatar image when an avatar URL is set
-(pure `AvatarImage` component + `AccountPage` display helpers). Merged to
-`master` at `5afaa64`.
+Current direction is front-end improvements to `psf-memo-client` (UI/UX polish,
+accessibility, performance, responsiveness, state handling, error surfacing).
 
 ## Notes for future cycles