memory: snapshot for context clear — the arc mid-flight, and the one thing that blocks

In-flight rewritten to what is actually live: design-dev's blur merge is HELD
at 5ded5ff awaiting his explicit 'merge it' ping (both panels dispatched 17:53,
unfolded), the redesign and thumbnails and dates are shipped, and the browser
suite is flaky under load and NOT fixed.

Two detail files added. The dates one is the reusable lesson: three plausible
proxies for a creation date were considered and one was nearly built, and the
real answer was a syscall away — the system already recorded what looked
unavailable. One of the rejected proxies was write-on-read, a shape this repo
had finished paying for hours earlier.

The flake entry is written as OPEN with its limits stated: three tests, two
real defects fixed, neither proven causal, and n=3 cannot show an improvement.

Recent decisions and Tried and abandoned preserved intact (49->51 by addition,
7 unchanged); the index is back under the soft cap at 141 lines from 285, all
of the reduction from settled history leaving the volatile section.

persistent-memory.d/2026-09-23-dates-and-the-guess-wearing-a-facts-clothes.md

@@ -0,0 +1,42 @@
+# Creation dates, and three guesses wearing a fact's clothes
+
+_2026-09-23 · booth_
+
+The operator asked for creation and update dates on booths. **Update** was
+already there — `landed_at`, the newest mtime among CONTENT excluding our own
+machinery. **Creation** had no honest source, and the interesting part is the
+three wrong answers.
+
+## Only 18 of 30 booths could state a creation time
+
+`.booth.json` carries a declared `created`, but it exists only for booths posted
+through the CLI since U5. Twelve live booths had nothing.
+
+## ⚠ Every convenient substitute was a GUESS PRESENTED AS A FACT
+
+- **Oldest content mtime** — wrong the moment an agent copies files with
+  timestamps preserved (`cp -p`, `rsync -a`), which is common. It would report
+  the SOURCE material's age as the booth's.
+- **Directory mtime** — that is "last thing added", i.e. `landed_at` under a
+  second name. Two fields, one meaning, displayed as if they were different.
+- **Stamp a first-seen marker on read** — and this is the one worth flagging,
+  because it is the same write-on-read shape that had *already* cost this
+  service an hour that same day when the thumbnail cache aged the booth it
+  cached ([[2026-09-23-the-cache-that-aged-the-thing-it-cached]]). A fix whose
+  shape you just finished paying for is not a fix.
+
+## The answer was a fact the disk already held
+
+**ext4 records a real birth time.** CPython does not expose `st_birthtime` on
+Linux, but `statx(2)` does and glibc has wrapped it since 2.28, so
+`booth/birthtime.py` reads it through `ctypes`. Verified against `stat(1)` on
+live booths: **6 of 6 exact**, including every booth with no manifest.
+
+One rule for all thirty, which is what invariant 6 asks of anything statable in
+a line. `None` when the filesystem cannot say (tmpfs, NFS, an old kernel), and
+**None renders as nothing** — a blank is the honest output when nobody knows,
+and better than a plausible number.
+
+**The generalisable bit:** when a fact seems unavailable, check whether the
+system already records it before reaching for a proxy. Three plausible proxies
+were considered and one was nearly built; the real answer was a syscall away.

persistent-memory.d/2026-09-23-the-browser-suite-is-flaky-under-load.md

@@ -0,0 +1,47 @@
+# The browser suite is flaky under load — UNRESOLVED, and owned by design-dev
+
+_2026-09-23 · booth_
+
+⚠ **OPEN. Not fixed. Do not read a green suite as proof of anything without
+re-running it.**
+
+## What is observed, with its limits
+
+**Three different browser tests** have each failed once under full-suite load
+while passing repeatedly in isolation:
+
+| test | owner | isolation | full suite |
+|---|---|---|---|
+| `test_the_keyboard_flag_actually_submits` | booth-dev | 5/5 pass | 1 failure |
+| `test_a_failed_save_says_so_reloads_and_never_re_posts` | design-dev | 3/3 pass | 1 failure |
+| `test_the_review_keys_judge_in_place_and_stay_out_of_the_note` | design-dev | 10/10 + 5/5 pass | 1 in ~9 |
+
+Three different tests points at **the environment under contention**, not at any
+one test. That is a direction, not a finding.
+
+## Two real defects found chasing it — NEITHER PROVEN TO BE THE CAUSE
+
+1. **A keypress race.** The flag test fired `ArrowRight` and `f` back to back,
+   assuming the first had finished — but `focus()` does a `scrollIntoView`, so
+   under load `f` could arrive with no cursor set. Now waits for
+   `figure.item.is-cursor`.
+2. **A port TOCTOU in BOTH browser fixtures.** Each did `bind → getsockname →
+   CLOSE → hand uvicorn the port NUMBER`, leaving a window for the kernel to
+   give that port away — and this suite runs two browser files that each start a
+   server per test, so the competitor is the other file. The bound socket is now
+   passed to `server.run(sockets=[sock])`.
+
+**Since those fixes: one failure in three full runs. n=3 CANNOT distinguish
+that from the prior rate, and no claim of improvement is made.**
+
+## Who owns it and what the method is
+
+**The operator ruled: "let him diagnose it properly."** design-dev owns it. His
+method: a trace hook keeping a Playwright trace (screenshots + DOM snapshots)
+for every browser test that fails, captured **from the run that fails**, then
+full-suite runs until red and the artefact decides. Test-only infra, on his
+branch as its own commit.
+
+⚠ **The methodological trap, and why the artefact must come from the full
+suite:** the failure only reproduces there. A narrowed repro that passes proves
+nothing and will be mistaken for a fix.