# lv-mccarthy v2 gate — pre-registration **Written 2026-09-21, before a single generation existed.** Everything below is fixed. The point of writing it down is that a threshold chosen after seeing the numbers is not a threshold. This is the third pre-registration in the line and it inherits the lv-hemingway design deliberately, so the two runs stay comparable; every place it departs is marked and argued. Nothing here may be amended after the first arm is generated. If the design turns out to be wrong, the run is wrong and gets re-run — the rule does not move. --- ## 1. What is being gated `gx10:~/r49-runs/mccarthy-4b-pairs-3ep/` — Qwen3-4B-Instruct + instruction-pair LoRA on the renamed McCarthy corpus (584,684 words, 167 units, 6 works, 6 renamed copies). 3-epoch schedule, seed 4919, rank 32 / alpha 64, lr 1e-4, seq 1536, 1,380 steps in 2h30m47s, finished **2026-09-18 00:49 PT**. `train_loss` 2.172, end-of-run `eval_loss` 2.4594. **The run outcome was unverified for three days** and this gate is the first read of it. That is recorded here rather than quietly fixed, because "the run finished" and "the run did what was configured" are different claims and only the second one is worth anything. ### 1a. Provenance defects found on first read, and their disposition | found | disposition | |---|---| | `provenance.json` `"run": "r49-babyyarros-pairs-pilot"` | **Cosmetic, not a mis-copy.** The same literal appears in the yarros AND hemingway provenance — it is a hardcoded label in `train_pairs_lora.py`, not a stale field for this run. Fix the harness; it invalidates nothing. | | `harness_commit: ""` | **Empty on all three runs.** The training harness never recorded its own commit. No claim in this gate rests on it. Named here so it is not re-discovered as news. | | `pairs_sha256_16` does not match `sha256sum` of the pairs file | **Not a defect.** It mismatches identically on yarros and hemingway too, so the harness computes it over the loaded records rather than the raw bytes. It is a consistent, per-corpus-unique cache key. | | `pairs` recorded as the relative `pairs/pairs-full.jsonl` | Resolved against the launch CWD `~/lv-mccarthy`. **Bound by count instead of by path**: `train_pairs` 3673 and `val_pairs_n` 269 match `lv-mccarthy/pairs/` exactly and match no other pair set on the box. | The run trained on McCarthy's pairs. That is established by the record counts and by `system_prompt_source: "pairs provenance (mccarthy)"`, not by the `run` label. ## 2. Arms — three, and the third is here for a different reason than Hemingway's was | arm | what it is | role | |---|---|---| | `base-unadapted` | `~/carriers/Qwen3-4B-Instruct`, no adapter | negative control for memorisation (never saw the corpus) **and** the voice baseline | | `ckpt900` | epoch 1.958, eval_loss **2.38706** — the curve's minimum | ship candidate | | `ckpt450` | epoch 0.980, eval_loss **2.4063** | **prior test**, see below | Measured on this run's own 56 eval points: **median neighbour jitter 0.00393**. ⚠ **`ckpt450` IS NOT TIED, and saying so is the point.** On Hemingway the second arm was in the run because the loss curve could not separate it (+0.9× jitter). Here it can: `ckpt450` sits **+0.0193 = 4.9× jitter** above the minimum. Three checkpoints *are* inside one jitter of the best — 875 (+0.4×), 850 (+1.1×), 925 (+1.5×) — and the choice of 900 among them is arbitrary and declared arbitrary; they are the same point on the curve. `ckpt450` is not one of them. So it is generated for a stated, falsifiable reason rather than as a coin-flip: - **The prior it tests.** On Brontë the earlier epoch-1 checkpoint won the tiebreak on the axes that resolve. On Hemingway the pair was tied and the question stayed open. **McCarthy is the first run in the line whose loss curve says epoch 2 is genuinely better than epoch 1.** That is a claim the axes can check, and checking it costs one arm. - **The thing it would buy.** Axis B (memorisation) carries more weight here than on any previous corpus — Brontë is public domain, Hemingway is not, and **McCarthy is in copyright with a living estate.** An earlier checkpoint is the cheap way to buy a lower verbatim-overlap rate. Whether it actually does is measured below, not assumed. **`adapter/` (end of run, epoch 3.0, 2.4594) is NOT gated.** At **+18.4× jitter** it is resolved by the loss curve alone — and note the curve does not drift there, it *steps*: 2.393 at step 925, 2.457 at step 950, and flat for the remaining 430 steps. The epoch-3 collapse reproduces the Hemingway finding on a second corpus. ⚠ The shipped `adapter/` directory is the epoch-3 weights. **Whatever ships is a checkpoint, not `adapter/`.** ## 3. Fixture and seeds — fixed now - **60 beats**, sampled by `build_beat_fixture.py` from `~/lv-mccarthy/pairs/pairs-val.jsonl` (held-out `split=val`, 269 pairs), `--seed 4919`, spread across works round-robin. - **`--max-words 140`, not the script's default 150.** McCarthy's register asks for 90–140 words and `score_beats.py` scores the in-band rate at 90–140. A fixture built at 90–150 would put reference passages outside the band the product asks for and the scorer measures. **207 of 269 val pairs are in-band**, across all six works (blood-meridian 51, all-the-pretty-horses 40, the-road 38, cities-of-the-plain 33, no-country-for-old-men 28, the-crossing 17). - **4 seeds: 1234 5678 9012 3456.** Same as lv-bronte and lv-hemingway. - → **240 generations per arm, 720 total.** 60 is carried over from Hemingway unchanged so the two floors are comparable; 207 in-band pairs make it available with room to spare (Hemingway had 173, Brontë 44). ## 4. The floor rule — inherited, unchanged **The noise floor for a candidate is the larger of the within-arm seed spreads of the TWO arms being compared: `max(spread(candidate), spread(base-unadapted))`.** Settled at lv-hemingway and not reopened. `voice_distance.py` prints both this and lv-bronte's all-arms floor and flags any case where the two rules disagree; the pairwise number is the verdict. ## 5. ⭐ THE VOICE AXIS — the open question, settled here before any number exists McCarthy's corpus measures **0.0 quote marks per 10k words** against Hemingway's 838, and `voice_distance.py` is Burrows's Delta over **character bigrams**. "Emit no quotation marks" is therefore the single cheapest available way to move this metric a long way without having learned a sentence. lv-mccarthy D1 flagged this and deferred it; it is settled now, in three parts. **5a. PRIMARY read — unchanged, and already hardened.** The `mccarthy` register names the punctuation on purpose (`build_sft_pairs.py` REGISTERS, commit `f3bf3ca`), and `eval-mccarthy.sh` drives **every** arm including `base-unadapted` with that same system prompt via `--system-from`. The control is therefore *told* to drop quote marks and write `dont`/`aint`/`wont`. The cheap win is handed to both sides and the adapter earns no delta for it. This was decided when the register was written, before any McCarthy number existed, and is not reopened here. **Stated cost: the voice axis is harder for this corpus than for Hemingway's, deliberately.** **5b. SECONDARY read — pre-registered, REPORTED, never the verdict.** `voice_distance.py --secondary-normalised` re-runs the entire analysis with all punctuation stripped from the reference and from every arm. A gap that survives is carried by words rather than by marks. ⚠ It is a **conservative lower bound, not a better measurement**: stripping terminal punctuation also strips sentence-length signal the adapter legitimately learned, and sentence length is a real McCarthy trait. It reads as *"at least this much of the primary gap is not the punctuation trick."* **It cannot overturn the primary verdict.** **5c. THE CONFOUND TRIGGER — the part that makes 5a falsifiable.** 5a's whole argument is that the base control *complies* with the instruction. That is an assumption about a model's behaviour, and it is checkable. `--punct-report` prints per-arm quote-mark, contraction-apostrophe and dash density against the reference, and evaluates this line: > **If `base-unadapted` quote density exceeds 100 marks per 10k words, the control > did not take the win it was handed, part of the primary gap IS the punctuation > trick, and the normalised secondary read (5b) is promoted to load-bearing for the > verdict.** 100 is the order-of-magnitude line between this corpus's 0.0 and Hemingway's 838, chosen now rather than after the table prints. **Instrument controls, run before this was committed.** The `voice_distance.py` refactor that added 5b and 5c reproduces the shipped lv-hemingway `voice_distance.txt` **byte for byte** on the default path (positive control: the edit did not move an existing record). `strip_punct` drops a quote-bearing sample's density from 2500.0 to **0.0** per 10k (negative control: the normalisation is not a no-op). On the Hemingway arms the secondary read still resolves a gap (ckpt1750 +0.410 at 7.3× floor) rather than flattening everything — so a null result from 5b on McCarthy would be a finding about McCarthy, not a blind detector. ## 6. The three axes, and what passes | axis | instrument | passes if | |---|---|---| | **A. VOICE** | `voice_distance.py --author McCarthy --punct-report --secondary-normalised` | `delta_cb(base) − delta_cb(candidate)` **exceeds the pairwise floor** on the PRIMARY read, unless 5c fires, in which case on the NORMALISED read | | **B. NOT COPIED** | `memorization_check.py` (longest verbatim n-gram vs the renamed copies, n=8) | hit-rate and max at or near `base-unadapted`, which never saw the corpus. Positive control (corpus vs itself) must saturate, or the zeroes are blind | | **C. NO DAMAGE** | `score_beats.py --metric-source raw` | in-band up on base beyond the metric's own floor; on-beat and ran-on not worse beyond it | ## 7. The decision rule — frozen 1. **`ckpt900` is the default ship candidate.** The loss curve resolves it above `ckpt450` at 4.9× jitter. 2. **`ckpt450` displaces it only if BOTH hold:** it is *not resolvably worse* on axis A (`gap_450 ≥ gap_900 − pairwise_floor`) **AND** it is *strictly better* on axis B by more than the base-to-candidate separation on that axis. Buying memorisation headroom is worth it; buying it by giving up the voice the adapter exists for is not. 3. **Axis C failure disqualifies that candidate outright**, whatever axis A says. 4. **If both candidates fail axis A** (gap inside the pairwise floor), the result is a **negative reported with its sensitivity floor**, and the ship-or-park call goes to the operator. The lv-bronte precedent — fail on A, clean on B and C, shipped anyway as additive and reversible — **does not transfer automatically**: Brontë is public domain and McCarthy is not, so axis B carries more weight in that conversation, not less. 5. **Nothing ships on the strength of the epoch-3 `adapter/`.** It is not gated. ## 8. Pre-flight — already run, and clean Both re-run at gate time rather than quoted from the 2026-09-17 session, because "it passed three days ago" is a claim about a tree that may have moved. **Leak gate** (`leak_gate.py --min-cap 8`, report `leak_gate_report.gate-time.json`): ``` 0 of 75 renameable · 0 of 37 sub-threshold · 0 separator-split survivors positive control 108/108 surfaces found in the unrenamed source negative control nonce absent · split-scan controls: planted `W olfenbarger` detected ``` **Beat-contamination audit** (`audit_pairs_sourcenames.py --min-cap 5`, mirroring the floor `rename.py` actually ran at), over **all 3,942 built pairs**: ``` BEAT naming a removed surface: 0 of 3942 (0.00%) RESPONSE naming a removed surface: 0 of 3942 (0.00%) controls green: 108/108 found in source · nonce absent from both trees ``` ⭐ **Zero, where Hemingway carried 70 of 7,094 contaminated beats (0.96%).** That is `build_sft_pairs.py --source-entities`, which was mandatory for this corpus's D4 and which Hemingway's pairs predate. The gate is unconfounded on both halves of the pair, not just the fixture half. **Sensitivity floor, stated as part of the pre-flight rather than as a footnote:** a name appearing fewer than 8 times per work is never detected and a phrase recurring fewer than 5 times is never audited — and **no phrase map exists for this corpus, so the phrase audit does not run at all.** Yarros and Brontë both had one. A clean leak gate here is a narrower claim than a clean leak gate there. ## 9. Reproduce ```bash # on pfi-gx10, ~/lv-mccarthy ./eval-mccarthy.sh # three arms, 60 beats, 4 seeds, all three axes ``` --- ## AMENDMENT 1 — 2026-09-21, axis B's negative control **Written while the `base` arm was still generating and before a single McCarthy delta_cb, memorisation rate or damage number had been read.** Recorded here rather than folded into the text above, so the order of events stays legible. ### What was wrong with §6 axis B as frozen §6 says axis B passes if hit-rate and max sit "at or near `base-unadapted`, which never saw the corpus". **The lv-hemingway gate record already establishes that this control is defective**, and I wrote the clause anyway: > `memorization_check.py` uses the base-unadapted arm as its negative control, but > base writes 18,035 words of *summary* against the adapted arms' 27,413 of > *pastiche* — text that does not imitate the register cannot collide with its > n-grams, so a 0.00 there means "different register", not "did not memorise". > — `persistent-memory.d/2026-09-17-lv-hemingway-gate.md` A negative control that differs from the candidate in a way **correlated with the metric** is not a control. Base's zero is unearned, and an axis that passes by comparing against an unearned zero is not measuring anything. There is a second, smaller fault in the same instrument: it builds its n-gram set from **every** record in the renamed copies, val included. The adapter never trained on val, so a collision with val text is counted as memorisation of training text when it is not. Brontë's and Hemingway's numbers carry this overcount too. ### What is added Two things, both **strictly harder to pass**. Neither can turn a failing candidate into a passing one; both can turn a passing one into a failing one. 1. **The correct negative control: the author himself.** Held-out (val) text — real McCarthy no arm trained on, in the same register as the candidates by construction — chunked to the arms' own median generation length and scored against the training text. This is the innocent-sample rate. On Hemingway it was **0.01 against the adapter's 0.07**, which refuted the comfortable "his plain register makes collisions inevitable" story rather than assuming it. 2. **A train-only n-gram set**, so a collision with held-out text is not counted as memorisation of the training text. The inherited all-records number is printed alongside it, because Brontë's and Hemingway's records were written with it and a reader comparing runs needs both. ### The amended axis B, and the amended tiebreak - **Axis B passes** if the candidate's hit-rate and max are at or near the **held-out-author reference**, not base. Base stays in the table as the register-mismatch marker it actually is. The positive control (train vs train) must still saturate or every zero in the table is blind. - **§7 rule 2 is amended to match**: `ckpt450` displaces `ckpt900` only if it is not resolvably worse on axis A **and** strictly better on axis B *measured against the held-out-author reference*. - **An elevated rate is not by itself a no-ship.** The lv-hemingway precedent is explicit that rate and exposure are different questions: it shipped at 7× the author's own rate because **every matched run was read** and every one was stock dialogue in the commonest words in English, max 9 words, no proper noun. The same reading is required here and is part of the axis, not a follow-up. ⚠ **McCarthy is in copyright with a living estate**, so a matched run carrying distinctive imagery or a proper noun is disqualifying in a way it was not for a rate number alone. ### Why this is not threshold-shopping The rule that must not move is the one that decides a result. This amendment moves the reference a candidate is compared against **from a known-broken one to a known- correct one**, in the direction that makes passing harder, on an argument published four days before this gate existed and independent of any McCarthy number — none of which had been read when this was written. The honest alternative was to run an axis whose control I already knew to be unearned. --- ## AMENDMENT 2 — 2026-09-21, the confound trigger's own instrument was broken **Read the order of events before the numbers, because the order is the point.** The base arm finished first, so §5c's trigger became evaluable while the two adapted arms were still generating. I evaluated it, **saw it FIRE**, and only then — reading the reference row of my own table — found that the detector was measuring the wrong thing. No delta_cb, memorisation rate or damage number had been read at any point. ### The bug `voice_distance.py`'s quote-mark class shipped as ``"'‘’“”«»‹›‚„` `` — it included the apostrophe characters. So it was an **apostrophe counter wearing a quote-mark label**, on a corpus whose defining tic is `dont`/`aint`/`wont` and whose possessives are everywhere. ``` as implemented TRUE quote marks all apostrophes held-out McCarthy ref 121.1 0.0 121.1 base-unadapted 224.7 19.9 204.8 held-out Hemingway ref 1112.6 694.7 351.7 ``` The corrected column is the one the pre-registration names: **0.0 for this corpus**, which is exactly what `build_corpus_mccarthy.py` asserts, and **694.7 for Hemingway's val split**, which is the documented ~838 scale the 100-per-10k line was anchored to. The as-implemented column matched neither, so it was never measuring the quantity §5c specified. ### The two readings, and why I am not choosing between them ``` as implemented (apostrophe-inclusive) base 224.7 > 100 -> TRIGGERED as specified (quote marks only) base 19.9 < 100 -> does NOT trigger ``` Fixing a detector so it measures the quantity the frozen rule names is not moving the rule. **But I saw the firing value first and the fix un-fires it, which is precisely the shape of threshold-shopping**, and no reader should have to take my word about my own motives. So the trigger is made moot instead of adjudicated: > **For this gate the NORMALISED SECONDARY READ (§5b) is load-bearing UNCONDITIONALLY, > whichever reading of §5c you accept.** Both quote-mark columns are reported. The bug fix > therefore has no effect on the verdict, and the conservative branch is taken by default. There is an argument for that independent of the bug, and it is the better reason: **base's true quote density is 19.9 against the reference's 0.0, so it did not fully comply.** A small residual cheap win is genuinely available to the adapter, and the normalised read is what prices it. A trigger threshold is a blunt instrument for a residual this size; running the conservative read always is simply better than deciding when to. ### What changed in the code `_QUOTE_RE` is quote marks only. Apostrophes get their own column and are never folded back in. `--punct-report` now prints quote-marks, all-apostrophes, contraction-apostrophes and dashes, so a future reader can see the thing that fooled this one. ### The durable lesson This is the same failure the r49 line keeps finding, in a new place: **a detector validated only against the present case cannot tell a wrong measurement from a right one.** I controlled `strip_punct` (2500 → 0, it works) and the byte-identity of the default path (it matches), but I never asked the quote counter for a value I already knew the answer to. The corpus asserts 0.0. Reading 121.1 against a known 0.0 is what exposed it — and that check cost one line and was available before the gate ever launched. --- ## AMENDMENT 3 — 2026-09-21, §6 axis C is UNSATISFIABLE and therefore void **This is arithmetic, not a re-reading of results.** Criterion 1 of §6 axis C, as frozen, requires the candidate's in-band rate to exceed the base control's by more than the metric's own floor. On this run: ``` needs in_band(candidate) - 0.89 > 0.200 i.e. in_band(candidate) > 1.09 ceiling in_band(candidate) <= 1.00 a rate cannot exceed 1 ``` **A PERFECT adapter — every one of 240 generations inside the 90–140 band — scores +0.11 against a floor of 0.200 and fails by 0.09.** No artifact can pass it. A criterion that no possible candidate can satisfy does not adjudicate anything, so "both candidates failed axis C" carries **zero information about either candidate**; that verdict was determined before a single generation existed. This is my error and it has a specific cause: §6 transcribed `score_beats.py`'s **v1** criteria, which the operator **amended on 2026-09-15** — *before this corpus was built* — precisely because they gate on metrics the unadapted carrier already maxes: > *"The defect in v1: it gated on metrics the UNADAPTED carrier already maxes. … Those three > axes can only detect DAMAGE that training does. … NOT carried into v2: in-band > (unresolvable — base maxes it) and on-beat."* — `score_beats.py`, operator-authorised > amendment, 2026-09-15 ### The governing rule reverts to the operator's own v2 **Axis C is `ran-on` only**: the candidate's ran-on rate must not exceed the base control's by more than the metric's floor. That is the rule the operator ratified, the rule lv-hemingway shipped under, and it predates this gate by three weeks. Reverting a transcription error to its source is not threshold-shopping — the source is older than the data. ⚠ **But it does not rescue ckpt450 either, and the bar for that is set HERE, before the numbers that could clear it exist.** Under the corrected axis C, ckpt450's ran-on is +0.19 against a floor of 0.200 — a pass by **0.01**, which is inside the noise the floor exists to describe. A marginal pass is not a pass worth shipping on an author in copyright with a living estate. ### AMENDMENT 3's added arms and its added bar The damage grows monotonically with epoch (base 1% over-band → ckpt450 20% → ckpt900 28%), and `--save-total-limit 60` kept all 56 checkpoints. So two more arms are gated, **on the same frozen fixture, the same four seeds and the same rule** — adding candidates does not move a bar: | arm | epoch | why | |---|---|---| | `ckpt300` | 0.652 | the damage may not have arrived yet; the voice may have | | `ckpt225` | 0.489 | the same question half an epoch earlier | **A candidate ships from this gate only if ALL of the following hold. Fixed now, before either arm is generated:** 1. **Voice** — gap over base exceeds the pairwise floor on the PRIMARY read **and** on the normalised read (§5b, load-bearing per AMENDMENT 2). 2. **Memorisation** — hit-rate and max at or near the **held-out-author reference** (0.12 / max 12), per AMENDMENT 1, with every matched run read. 3. **Damage** — `ran-on` delta over base **at most 0.100**, i.e. **half the measured floor**. Not "inside the floor": half of it. This is the bright line ckpt450's +0.19 fails, chosen because a rate that clears a noise threshold by 5% of that threshold has not been shown to clear it at all. If no candidate clears all three, lv-mccarthy is **parked pending a retrain**, and that is the report — not a softer bar.