… (7/8 falsifiers bound) (#1480)

Same-day continuation cycle landed 8 PRs across the §50.4 architecture-
polymorphic infrastructure track. §51 records the cascade-complete
state and pinpoints the remaining MODEL-2 ship-% gate (step 5g LIVE).

Falsifier-discharge scoreboard for `apr-pretrain-arch-polymorphic-v1`:

  | ID | What it pins                          | PR    | Status |
  |----|---------------------------------------|-------|--------|
  | 001 | qwen2_0_5b matches HF + tie fix      | #1474 | PARTIAL |
  | 002 | init=None preserves Llama370M        | #1475 | PARTIAL |
  | 003 | init=Some pass-through               | #1475 | PARTIAL |
  | 004 | GQA-7:1 forward smoke                | #1478 | MERGED  |
  | 005 | Qwen tokenizer + Qwen target = pass  | #1476 | MERGED  |
  | 006 | Qwen tokenizer + Llama target = fail | #1476 | MERGED  |
  | 007 | encoder/decoder family mismatch      | #1479 | PARTIAL |
  | 008 | pv validate                          | #1473 | PARTIAL |

7 of 8 falsifiers PARTIAL_ALGORITHM_LEVEL or MERGED.

Remaining work:
  - 5f.2 — wire APR file open + tensor materialization (~80 LOC)
           DELIBERATELY DEFERRED this cycle; doing 5f.2 now means
           rebasing onto 4 in-flight PRs as they land
  - 5g  — LIVE 500-step smoke fine-tune (operator dispatch)
          THE LOAD-BEARING TEST that moves MODEL-2 ship-%
  - 5h  — stamp + publish

Per §47-§48 lesson: "infrastructure shipped ≠ ship-% movement."
Cascade-complete state means the polymorphic foundation is in place;
ship-% movement still requires the LIVE empirical check.

Five Whys:
  1. Why a snapshot now? Multiple PRs in cascade auto-merge create
     cognitive load. A spec snapshot captures both the achievement
     (7 falsifiers bound) and the remaining gate (step 5g LIVE).
     Without it, future operators waste cycles re-deriving the state.
  2. Why focus on falsifier scoreboard rather than total LOC? Falsifier
     discharge is the actual contract obligation. 7/8 invariants pinned
     means CI now catches regressions in the polymorphic-init path.
  3. Why mention 5f.2 explicitly as deliberately deferred? Naming the
     deferral makes it not a punt. Step 5f.2 has a clear "when": after
     the 4 in-flight PRs cascade-merge, then 5f.2 lands clean.
  4. Why call out infrastructure ≠ ship-%? The §47-§48 cascade taught
     the same lesson — "11 SHIP-007 cascade PRs landed but no ship-%
     movement." Operator-facing ship-% is the LIVE check.
  5. Why is FALSIFY-006 LIVE the load-bearing claim? init_loss(step=0)
     ≤ 6.0 vs from_scratch_loss(step=0) ≥ 9.5 proves end-to-end
     correctness in one number. No other falsifier can substitute.

Plain ship-% update:
  - MODEL-1: unchanged at 91% (SHIP-007 cascade infrastructure track)
  - MODEL-2: unchanged at 57% — first ship-% movement gated on §50.4
    step 5g (LIVE 500-step fine-tune producing val_loss < 9.38)

Spec amendment cadence: §41 → §42 → §43 → §44 → §45 → §46 → §47 →
§48 → §49 → §50 → §51. Eleven amendments since 2026-05-03. Same-day
spec hygiene rather than letting the cascade-complete state remain
implicit.

Refs:
  - SPEC-SHIP-TWO-001 §50 — architecture-coupling finding (PR #1472, MERGED)
  - PR #1473 — apr-pretrain-arch-polymorphic-v1 contract (in flight)
  - PR #1474 — qwen2_0_5b tie_word_embeddings fix (in flight)
  - PR #1475 — build_transformer_config polymorphic dispatch (in flight)
  - PR #1476 — preflight_tokenizer_vocab_matches_target (MERGED)
  - PR #1478 — GQA-7:1 forward-pass smoke test (MERGED)
  - PR #1479 — validate_pretrain_init_arch_compatible (in flight)
  - feedback_no_guessing.md

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

…1481)

Adds the read-half of `apr pretrain --init` weight load: a thin
wrapper over `aprender::format::converter::load_model_tensors` that
returns a `BTreeMap<String, (Vec<f32>, Vec<usize>)>` of tensor blobs
keyed by HF naming convention.

Per `apr-pretrain-arch-polymorphic-v1` §init_load_semantics (PR #1473):
"Loader is REUSED, not reimplemented." This function does not duplicate
APR parsing — it forwards to the same machinery `apr export` and
`apr inspect` use.

Discharges from `apr-pretrain-arch-polymorphic-v1`:
  - §init_load_semantics invariant (loader reuse): satisfied
  - FALSIFY-006 (init_loss < 6.0) at READ-COMPILE-BIND level

Step 5f decomposition:
  - 5f.1 (PR #1479): encoder/decoder family validator (~30 LOC)
  - 5f.2 (this PR): APR file open + tensor read (~30 LOC + 2 tests)
  - 5f.3 (next):    populate trainer parameters from BTreeMap (~50 LOC)
  - 5g  (operator): LIVE 500-step fine-tune → DISCHARGES MODEL-2 ship-%

Step 5f.2 is intentionally narrow — it only does the READ. Population
into trainer parameter slots (5f.3) reconciles HF naming convention
(e.g., `model.embed_tokens.weight`) against the trainer's internal
parameter naming. That's a separate concern with its own falsifier.

What this PR adds:

  1. `pub fn load_init_tensors_from_apr(path) -> Result<BTreeMap<...>>`
     at pretrain_real.rs:35 (~25 LOC including doc comment)
  2. 2 unit tests in `pretrain_real::tests`:
       - load_init_tensors_missing_file_errors_with_falsifier_id
         (FALSIFY-006 fail-fast path; asserts error message contains
          falsifier id + offending path for operator-experience)
       - load_init_tensors_signature_compile_bind
         (drift-prevention: catches a future signature change that
          would break step 5f.3's BTreeMap consumer)

Test results (cargo test -p aprender-train --lib train::pretrain_real::tests::load_init_tensors):
    2 passed; 0 failed; 0 ignored

Five Whys:

  1. Why decompose step 5f.2 to JUST the read? Single-piece flow.
     Read → Validate → Populate are three distinct concerns. Step 5f.1
     did validation (#1479); 5f.2 does read; 5f.3 will do populate.
     Each PR has one falsifier discharge story.

  2. Why use load_model_tensors and not write a new parser? The contract
     pins "Loader is reused, not reimplemented." Writing a new parser
     would create a parallel format-decoder that drifts from the canonical
     one. The same lesson as the LAYOUT-001/002 hits — parallel format
     code paths produce silent format-drift bugs.

  3. Why return BTreeMap<String, (Vec<f32>, Vec<usize>)> rather than a
     trainer-parameter-shaped struct? Decoupling: the read shouldn't
     know about TransformerTrainer's internal parameter names. Step
     5f.3's job is to map HF names → trainer slots; if 5f.2 baked that
     mapping in, every change to TransformerTrainer would break the read.

  4. Why include the signature-compile-bind test? It's a compile-time
     check that drives step 5f.3's expectations. If a future refactor
     changes the return type (e.g., from BTreeMap to HashMap, or from
     Vec<usize> to Box<[usize]>), step 5f.3's consumer code stops
     compiling — caught here, not at the integration point.

  5. Why is FALSIFY-006 NOT yet at PARTIAL_ALGORITHM_LEVEL after this
     PR? Because step 5f.2 only does the read; FALSIFY-006 requires
     the LIVE init_loss < 6.0 check, which needs steps 5f.3 + 5g.
     This PR moves FALSIFY-006 from UNBOUND → READ-COMPILE-BIND, a
     sub-level of PARTIAL_ALGORITHM_LEVEL. Full PARTIAL discharge
     happens at 5f.3 when the populate step exists.

Plain ship-% update:
  - MODEL-1: unchanged at 91% (SHIP-007 cascade infrastructure track)
  - MODEL-2: unchanged at 57% — first ship-% movement gated on §50.4
    step 5g (LIVE 500-step fine-tune producing val_loss < 9.38)

Refs:
  - SPEC-SHIP-TWO-001 §50, §51 — MODEL-2 architecture-coupling +
    cascade snapshot (PR #1472, #1480 MERGED)
  - PR #1473 — apr-pretrain-arch-polymorphic-v1 contract (in flight)
  - PR #1474 — qwen2_0_5b tie_word_embeddings fix (MERGED)
  - PR #1475 — build_transformer_config polymorphic dispatch (in flight)
  - PR #1476 — preflight_tokenizer_vocab_matches_target (MERGED)
  - PR #1478 — GQA-7:1 forward-pass smoke test (MERGED)
  - PR #1479 — validate_pretrain_init_arch_compatible (in flight)
  - feedback_no_guessing.md
  - feedback_falsifier_first_cascade_pattern.md (this turn's pattern)

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

… 5f.3

Add `populate_trainer_from_init_tensors(transformer, init_tensors)` —
the population half of `apr pretrain --init`. Iterates the model's
`named_parameters()` set, looks up each name in the init BTreeMap (HF
naming preserved by §50.4 step 5f.2's loader), validates length, and
calls `Transformer::set_named_parameter()`.

`apr-pretrain-arch-polymorphic-v1` §init_load_semantics:
  - Population invariant: "Init tensors populate trainer parameters
    byte-equivalent to source"
  - FALSIFY-APR-PRETRAIN-INIT-007 (population step) at PARTIAL_ALGORITHM_LEVEL

1. **Why strict on missing-required?** Architecture mismatch (e.g., init
   from a different model family) would silently leave random init for
   absent parameters, which §28's SHIP-007 lesson teaches us is the
   exact class of "silent gibberish" defect that hides for many epochs.
2. **Why strict on length-mismatch?** A length mismatch indicates the
   from_apr_metadata extractor misread a shape — populating regardless
   would silently truncate or pad, masking the bug.
3. **Why permissive on extra-init-entries?** Tied embeddings: a Qwen2.5
   APR may publish a separate `lm_head.weight` that the trainer's tied
   model omits. Failing on extra entries would force operators to
   pre-strip APRs, which is muda.
4. **Why FALSIFIER ID in error message?** §28 lesson — falsifier IDs in
   error messages turn opaque CI failures into self-explaining defects.
5. **Why one function not two (load+populate fused)?** Decoupling keeps
   `aprender-train` free of `aprender-serve` (the APR loader): the
   loader is a free function in §50.4 step 5f.2; this is the consumer.
   Two-step composition is testable independently (and is, in this PR).

- `populate_trainer_from_init_tensors_happy_path`: every param matched
  → returns Ok(N) where N = named_parameters().len()
- `populate_trainer_from_init_tensors_extra_entries_silently_ignored`:
  fictitious extra entry must NOT cause Err (tied-embeddings safety)
- `populate_trainer_from_init_tensors_rejects_length_mismatch`: wrong
  flat length → Err naming the param + falsifier ID
- `populate_trainer_from_init_tensors_rejects_missing_required_param`:
  missing required → Err with "not present in init APR" + falsifier ID

All 12 tests pass; cargo clippy --lib clean.

- [x] `cargo test -p aprender-train --lib train::pretrain_real::tests` (12/12 pass)
- [x] `cargo clippy -p aprender-train --lib -- -D warnings` (clean)
- [x] No new dependencies; pure aprender-train + autograd Tensor + std::collections::BTreeMap

Step 5f.3 caps the §50.4 step-5f sub-cascade:
  5f.1 — encoder-family validator (PR #1479, awaiting CI)
  5f.2 — load_init_tensors_from_apr (PR #1481 MERGED)
  5f.3 — THIS PR (populate_trainer_from_init_tensors)
Remaining roadmap: 5g (LIVE 500-step fine-tune, operator dispatch),
5h (stamp + publish as MODEL-2 v2).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

…PARTIAL_ALGORITHM_LEVEL — §50.4 cascade snapshot (#1482)

## Summary

Bump `apr-pretrain-arch-polymorphic-v1` contract status from PROPOSED to
PARTIAL_ALGORITHM_LEVEL. All 8 FALSIFY-APR-PRETRAIN-ARCH-* falsifiers
are now bound to executable tests across the §50.4 cascade.

## Falsifier scoreboard (post-§51 snapshot)

| ID         | Rule                                          | PR                | Status                |
|------------|-----------------------------------------------|-------------------|-----------------------|
| FALSIFY-001 | qwen2_0_5b matches HF config                  | #1474 merged      | PARTIAL_ALGORITHM_LEVEL |
| FALSIFY-002 | build_transformer_config(None) → Llama370M    | #1475 merged      | PARTIAL_ALGORITHM_LEVEL |
| FALSIFY-003 | build_transformer_config(Some) extracts 10    | #1475 merged      | PARTIAL_ALGORITHM_LEVEL |
| FALSIFY-004 | GQA-7:1 forward-pass smoke                    | #1478 merged      | PARTIAL_ALGORITHM_LEVEL |
| FALSIFY-005 | Qwen tokenizer passes with --init Qwen        | #1476 merged      | PARTIAL_ALGORITHM_LEVEL |
| FALSIFY-006 | Qwen tokenizer fails without --init           | #1476 merged      | PARTIAL_ALGORITHM_LEVEL |
| FALSIFY-007 | encoder-arch APR fail-fast                    | #1479 open (auto-merge armed) | PARTIAL_ALGORITHM_LEVEL |
| FALSIFY-008 | contract self-validates via pv                | this PR (validates clean) | PARTIAL_ALGORITHM_LEVEL |

## Test plan

- [x] pv validate contracts/apr-pretrain-arch-polymorphic-v1.yaml exits 0
- [x] All 8 falsifiers cite a concrete test path or PR
- [x] Changelog entry under metadata.changelog with version/date/change

## Why now

Per `feedback_falsifier_first_cascade_pattern.md`: when a saturated
auto-merge queue (≥4 PRs) blocks more impl PRs, switch to non-conflict
work. This contract bump:
  - touches only one YAML file (no Rust/test source)
  - cannot conflict with #1479 / #1481 (impl PRs)
  - audit-trails the cascade scoreboard

Promotion to FUNCTIONAL is gated on #1479 landing (FALSIFY-007 PASS).
Promotion to DISCHARGED is gated on §50.4 step 5g LIVE empirical run.

## Five Whys

1. Why bump status now? — 7/8 falsifiers bound on main + 8th bound on
   open PR; PROPOSED is stale.
2. Why not wait for #1479 land first? — §51 snapshot recorded "7/8
   PARTIAL bound" 2 hours ago; the 8th binding is the contract-self
   validation, which is met by THIS PR's `pv validate` output.
3. Why not bundle with #1479? — Different file, different review scope,
   different concern (status semantics vs. impl).
4. Why not skip the bump? — Operator-facing scoreboard is in the YAML;
   stale PROPOSED implies "not yet started" which contradicts §51.
5. Why YAML changelog instead of just version? — Changelog records
   THIS bump's reasoning so future operators don't re-derive it from
   git log.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

…LETE + 5f.4 wireup gap identified (#1486)

## Summary

Same-day continuation of §51 cascade landed PR #1479 (FALSIFY-007
encoder/decoder validator) and PR #1481 (load_init_tensors_from_apr).
PR #1483 (5f.3 populate) and PR #1482 (contract status bump) are
MERGEABLE in queue. All 8 falsifiers in `apr-pretrain-arch-polymorphic-v1`
are now PARTIAL_ALGORITHM_LEVEL bound on main or about to land.

§52 records:
1. Updated falsifier scoreboard (8/8 vs §51's 7/8)
2. NEW step 5f.4 (CLI wireup, ~150 LOC) identified via live source
   inspection of `apr-cli/src/commands/pretrain.rs:259-297`
3. Step 5g LIVE 500-step fine-tune is now gated on 5f.4 landing first

## Why now

Per `feedback_falsifier_first_cascade_pattern.md`: when a saturated
auto-merge queue blocks more impl PRs (#1483 + #1482 both in queue
touching pretrain_real.rs), switch to non-conflicting work. This spec
amendment touches one markdown file with no PR conflicts.

## Five Whys (§52.8 in body)

1. Why didn't §50 catch 5f.4? — top-down arch-coupling lens missed the
   CLI-dispatch seam.
2. Why is 5f.4 separate from 5f.3? — different crate (apr-cli vs
   aprender-train).
3. Why must 5f.4 be atomic? — removing "not yet wired" Err without the
   wireup produces silent random-init (§28 SHIP-007 defect class).
4. Why ~150 LOC? — 4 levels of plumbing + new builder + tests + CUDA.
5. Why call 5f.4 out in spec? — without §52, readers would assume 5g
   is dispatchable; spec is the source of truth.

## Test plan

- [x] Single markdown file, no Rust changes
- [x] Falsifier scoreboard table updated to 8/8 PARTIAL_ALGORITHM_LEVEL
- [x] Step roadmap table adds 5f.4 between 5f.3 and 5g
- [x] Cadence preserved: §41 → ... → §51 → §52 (12 amendments since 2026-05-03)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

… 5f.3 (#1483)

Add `populate_trainer_from_init_tensors(transformer, init_tensors)` —
the population half of `apr pretrain --init`. Iterates the model's
`named_parameters()` set, looks up each name in the init BTreeMap (HF
naming preserved by §50.4 step 5f.2's loader), validates length, and
calls `Transformer::set_named_parameter()`.

`apr-pretrain-arch-polymorphic-v1` §init_load_semantics:
  - Population invariant: "Init tensors populate trainer parameters
    byte-equivalent to source"
  - FALSIFY-APR-PRETRAIN-INIT-007 (population step) at PARTIAL_ALGORITHM_LEVEL

1. **Why strict on missing-required?** Architecture mismatch (e.g., init
   from a different model family) would silently leave random init for
   absent parameters, which §28's SHIP-007 lesson teaches us is the
   exact class of "silent gibberish" defect that hides for many epochs.
2. **Why strict on length-mismatch?** A length mismatch indicates the
   from_apr_metadata extractor misread a shape — populating regardless
   would silently truncate or pad, masking the bug.
3. **Why permissive on extra-init-entries?** Tied embeddings: a Qwen2.5
   APR may publish a separate `lm_head.weight` that the trainer's tied
   model omits. Failing on extra entries would force operators to
   pre-strip APRs, which is muda.
4. **Why FALSIFIER ID in error message?** §28 lesson — falsifier IDs in
   error messages turn opaque CI failures into self-explaining defects.
5. **Why one function not two (load+populate fused)?** Decoupling keeps
   `aprender-train` free of `aprender-serve` (the APR loader): the
   loader is a free function in §50.4 step 5f.2; this is the consumer.
   Two-step composition is testable independently (and is, in this PR).

- `populate_trainer_from_init_tensors_happy_path`: every param matched
  → returns Ok(N) where N = named_parameters().len()
- `populate_trainer_from_init_tensors_extra_entries_silently_ignored`:
  fictitious extra entry must NOT cause Err (tied-embeddings safety)
- `populate_trainer_from_init_tensors_rejects_length_mismatch`: wrong
  flat length → Err naming the param + falsifier ID
- `populate_trainer_from_init_tensors_rejects_missing_required_param`:
  missing required → Err with "not present in init APR" + falsifier ID

All 12 tests pass; cargo clippy --lib clean.

- [x] `cargo test -p aprender-train --lib train::pretrain_real::tests` (12/12 pass)
- [x] `cargo clippy -p aprender-train --lib -- -D warnings` (clean)
- [x] No new dependencies; pure aprender-train + autograd Tensor + std::collections::BTreeMap

Step 5f.3 caps the §50.4 step-5f sub-cascade:
  5f.1 — encoder-family validator (PR #1479, awaiting CI)
  5f.2 — load_init_tensors_from_apr (PR #1481 MERGED)
  5f.3 — THIS PR (populate_trainer_from_init_tensors)
Remaining roadmap: 5g (LIVE 500-step fine-tune, operator dispatch),
5h (stamp + publish as MODEL-2 v2).

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Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

…ep 5f.4 (#1494)

## Summary

Wire `apr pretrain --init <PATH>` end-to-end so step 5g LIVE 500-step
fine-tune can dispatch. Replaces the §49 step 4 "not yet wired" Err
with the actual init-tensor load + trainer populate path that
§50.4 steps 5f.1/5f.2/5f.3 made possible.

## Architecture

Two functions added/changed:

1. `entrenar::train::pretrain_real::build_shared_trainer_with_init` —
   composes the §50.4 step-5f machinery (5c polymorphic dispatch +
   5f.1 encoder rejection + 5f.2 load + 5f.3 populate) into a single
   trainer-builder entry. init=None preserves the from-scratch baseline
   byte-equivalent to `build_shared_trainer`. init=Some validates arch
   family, builds the polymorphic config, loads tensors, populates.

2. `apr-cli/src/commands/pretrain.rs::run` — now extracts the init APR
   file's TransformerConfig via existing `model_config::read_apr_architecture`
   when `--init` is set, then plumbs both `init_arch` and `init_path`
   through `drive_real → drive_real_cpu → build_shared_trainer_with_init`.
   The polymorphic preflight (§50.4 step 5d) already used the EXTRACTED
   vocab — this PR wires the call site to actually pass it.

## What this PR DOES NOT do

- **CUDA path** (~80 LOC follow-up as 5f.5): `drive_real_cuda` now
  fail-fasts when --init is set rather than silently using random init
  (FALSIFY-APR-PRETRAIN-INIT-CUDA-001). The cuBLAS trainer needs
  symmetric `build_shared_cuda_trainer_with_init` which is out of scope.
- **Step 5g LIVE 500-step fine-tune** (operator dispatch): this PR makes
  it dispatchable; running the 500 steps requires operator action.

## Discharges (per apr-pretrain-arch-polymorphic-v1)

- §init_load_semantics integration: load + populate composed end-to-end
- §arch_extraction_signature integration: read_apr_architecture wired
- §qwen_tokenizer_vocab_compatibility integration: extracted vocab
  flows into preflight call site (no longer hardcoded Llama370M)
- FALSIFY-APR-PRETRAIN-INIT-007 (population) at INTEGRATION level
- The legacy "not yet wired" guard from §49 step 4 is RETIRED — the
  drift-prevention test now pins the new fail-closed semantic.

## Tests (8 new across 2 crates, all pass)

- `aprender-train`: 4 new tests for `build_shared_trainer_with_init`:
  - `_none_uses_llama370m_shape` (regression-free init=None)
  - `_rejects_unpaired_args` (caller-bug guard)
  - `_rejects_encoder_family` (FALSIFY-007 integration)
  - `_decoder_family_proceeds_to_tensor_load` (failure ordering pin)
- `apr-cli`: 2 retrofitted tests for the new fail-closed semantic:
  - `pretrain_init_valid_magic_but_bogus_metadata_fails_at_arch_extraction`
    (replaces the old "not yet wired" trip-wire)
  - `pretrain_init_v1_magic_aprn_passes_validate_init_apr_path`
    (helper now returns Ok on valid magic)

19/19 pretrain_real tests pass. 23/23 apr-cli pretrain tests pass.
cargo clippy --lib -- -D warnings clean across both crates.

## Five Whys

1. **Why was 5f.4 needed at all?** §50's 5a-5h decomposition assumed
   the CLI dispatch would naturally invoke the helper functions; live
   source inspection (§52 amendment) revealed the dispatch hardcoded
   "not yet wired" Err. 5f.4 is the explicit wireup.
2. **Why is removing the safety Err so load-bearing?** The §28 SHIP-007
   lesson: silently random-init via a half-implemented dispatch is the
   exact "silent gibberish" defect class. Removing the safety Err
   without the wireup would manifest as a multi-epoch divergence
   masquerading as a corpus-quality issue.
3. **Why a separate polymorphic builder rather than overload `build_shared_trainer`?**
   `build_shared_trainer` enforces INV-ARCH-370M-001 (param-count band)
   which only applies to from-scratch Llama370M. The polymorphic builder
   sidesteps it by design — Qwen2.5-0.5B is 0.5B params, outside the
   band by intent.
4. **Why fail-fast on `--init` + `--device cuda` rather than silently
   ignore?** Same reasoning as #2: silent CUDA random-init would
   bisect the same "silent gibberish" class. 5f.5 follow-up wires
   symmetric CUDA path; until then, fail-closed.
5. **Why couldn't this be inside #1483 (the populate PR)?** Different
   crate (apr-cli vs aprender-train), different review concern (CLI
   plumbing vs trainer mutation), different test surface. One atomic
   PR per file/crate boundary.

## Test plan

- [x] `cargo test -p aprender-train --lib train::pretrain_real::tests` (19/19 pass)
- [x] `cargo test -p apr-cli --lib commands::pretrain` (23/23 pass)
- [x] `cargo clippy -p aprender-train -p apr-cli --lib -- -D warnings` (clean)
- [x] `cargo check -p apr-cli --lib` (clean)
- [ ] Operator-dispatched: `apr pretrain --init <Qwen2.5-Coder-0.5B>.apr`
      smoke that fires 50 training steps end-to-end (5g LIVE prelude;
      operator action in next session)

## Cascade context

This is the §52-identified gap closing the §50.4 step 5f sub-cascade:
- 5f.1 encoder validator: PR #1479 ✅ MERGED
- 5f.2 load_init_tensors_from_apr: PR #1481 ✅ MERGED
- 5f.3 populate_trainer_from_init_tensors: PR #1483 (mergeable, in queue)
- **5f.4 CLI wireup: THIS PR**
- 5g LIVE 500-step fine-tune: operator dispatch (next)
- 5h stamp + publish: ~10 LOC follow-up

Once 5f.4 lands AND 5g produces val_loss < 9.38 evidence, MODEL-2 ship % moves 57% → ≥58%.

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Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

…ION-COMPLETE; contract v1.1.0 → v1.2.0 FUNCTIONAL (#1495)

§50.4 cascade INTEGRATION-COMPLETE on main with PR #1494 merging at
2026-05-05T01:48:14Z. The `apr pretrain --init <PATH>` flow is now
end-to-end functional on CPU; the legacy "not yet wired" Err is
RETIRED; step 5g LIVE is the only remaining gate before MODEL-2 ship-%
can move from 57% → ≥58%.

Spec amendment §53:
- Updated falsifier scoreboard: 6/8 INTEGRATION (001/002/003/005/006/007
  via live CLI dispatch); 2/8 PARTIAL_ALGORITHM_LEVEL (004 forward-pass
  smoke + 008 contract validation are inherently algorithm-level).
- Step roadmap: 5a-5f.4 ✅ MERGED; 5f.5 (CUDA wireup) NOT YET STARTED;
  5g (LIVE 500-step fine-tune) operator-dispatchable on RTX 4090.
- Cascade ships statistics: 11 PRs over 2 days
  (#1471/#1472/#1473/#1474/#1475/#1476/#1478/#1479/#1481/#1482/#1483/#1486/#1494).
- MODEL-1 ship % unchanged at 91%; MODEL-2 ship % unchanged at 57%
  (gated on 5g empirical val_loss < 9.38 evidence).
- 3 CI andon classes documented as feedback memories during cascade
  (workspace-test missing-binary, trueno SIGSEGV-on-cleanup, auto-merge
  behind-state).

Contract apr-pretrain-arch-polymorphic-v1 v1.1.0 → v1.2.0 FUNCTIONAL:
- All 8 falsifiers PASS on main; 6/8 reach INTEGRATION via the
  user-facing `apr pretrain --init` flow.
- verification_summary updated: tested 7 → 8; status partial →
  functional.
- Added §52 + §53 references.
- Promotion to DISCHARGED still requires §50.4 step 5g LIVE empirical
  500-step fine-tune on canonical Qwen2.5-Coder-0.5B-Instruct.apr
  producing val_loss < 9.38.

`pv validate contracts/apr-pretrain-arch-polymorphic-v1.yaml` exits 0.

Refs: SPEC-SHIP-TWO-001 §50.4 cascade, PR #1494 merge commit 9afca16

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

…-003/004/007 drift (round 2) (#1509)

* contract(apr-pretrain-arch-polymorphic-v1): v1.5 → v1.6 — fix FALSIFY-003/004/007 drift (round 2)

Second-round test-reference drift correction. §57's drift sweep
(this contract's v1.4 → v1.5 bump in PR #1505) caught FALSIFY-005/006
but a more thorough audit (cross-referencing every `test:` field
against the source-code function-name registry) surfaced three
additional dangling references.

## Drift inventory (round 2)

  | Falsifier | v1.5.0 cited test                                           | Exists? | Actual test                                                  |
  | ---       | ---                                                         | ---     | ---                                                          |
  | 003       | build_transformer_config_qwen_init_matches_constructor      | ❌       | build_transformer_config_qwen_init_matches_input             |
  | 004       | transformer::attention::tests::gqa_7_to_1_matches_full_mha  | ❌       | transformer::model::tests::falsify_apr_pretrain_arch_004_*   |
  | 007       | build_transformer_config_encoder_init_errors                | ❌       | validate_pretrain_init_arch_rejects_encoder                  |

## Why §57 (PR #1505) didn't catch these

§57's grep audited test-name SUFFIXES and FRAGMENTS, which produced
false-negatives on:
  - `_init_matches_constructor` vs `_init_matches_input` — both end
    in `_matches_<word>` so a fragment grep counted the contract's
    name as "not dangling"
  - `transformer::attention::tests::` vs `transformer::model::tests::` —
    module-path drift not just function-name drift; only fully-
    qualified path comparison catches this
  - `_encoder_init_errors` vs `validate_pretrain_init_arch_rejects_encoder` —
    the contract's name was a guess at the impl name; impl PR #1479
    chose a completely different convention

## How this round was found

Used a stricter audit: for every `cargo test ... ::tests::<name>`
in contracts, grep `fn <name>` in the actual source tree. If the
fn doesn't exist, drift. This catches drift that PR #1505's
fragment-based audit missed.

## Resolution

Update FALSIFY-003/004/007 `test:` fields to the actual function
names. No falsifier semantics change. 11 falsifiers all PASS;
contract status remains FUNCTIONAL.

## Verification

  $ cargo test -p aprender-train --lib -- build_transformer_config_qwen_init_matches_input
    test result: ok. 1 passed
  $ cargo test -p aprender-train --lib -- falsify_apr_pretrain_arch_004_gqa_7_1_forward_pass_smoke
    test result: ok. 1 passed
  $ cargo test -p aprender-train --lib -- validate_pretrain_init_arch_rejects_encoder
    test result: ok. 1 passed
  $ pv validate contracts/apr-pretrain-arch-polymorphic-v1.yaml
    0 error(s), 0 warning(s)

## Five Whys

1. Why did §57's sweep miss these? Used name-fragment grep
   (`::tests::[a-z_]+`) which counted false-negatives on suffix-
   close names like `_constructor` ↔ `_input`.
2. Why is module-path drift a separate class? Because grep against
   the `[a-z_]+` regex captures the FUNCTION name, not the
   `::module::tests::` path. A function with the right name in the
   wrong module passes that audit but fails actual test invocation.
3. Why fix in a separate PR rather than amending PR #1505? PR #1505
   already merged. Per `feedback_falsifier_first_cascade_pattern.md`
   the cleanest cadence is one-bump-per-PR.
4. Why bump to v1.6.0? Same pattern as PR #1505's v1.4 → v1.5: the
   test-binding INVARIANT was broken in v1.5.0 (residual drift) and
   v1.6.0 restores it.
5. Why now (during 5g.1 wait)? Productive use of the 5g.1 (~10hr
   remaining) compute-bound idle time. Each drift fix is small
   (~30 LOC), reduces drift risk for future agents, and restores
   the falsifier-binding invariant. The alternative (manufacture
   bigger work) would risk introducing defects the contract base
   doesn't catch yet.

## Net effects

- Contract v1.5.0 → v1.6.0 FUNCTIONAL.
- 11 falsifiers, all PASS — same count, but FALSIFY-003/004/007
  now reference tests that actually exist.
- MODEL-1 ship % unchanged at 91%.
- MODEL-2 ship % unchanged at 57% until 5g.3.

This is the SECOND round of drift sweep on this contract. Together
with PRs #1502/#1504/#1505/#1506 (round 1), all known
test-reference drift is closed across the §50.4 cascade contracts.
A future spec amendment could codify a `pv lint --strict-test-binding`
enforcement that prevents drift at contract-merge time.

Refs: SPEC-SHIP-TWO-001 §50.4 cascade,
      contracts/apr-pretrain-arch-polymorphic-v1.yaml v1.6.0,
      PR #1505 (round 1 partial fix), PR #1502/#1504/#1506 (sibling fixes)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

* contract(apr-pretrain-arch-polymorphic-v1): also fix FALSIFY-001 (round 2.5 — surfaced by PR #1511)

Round 2 (initial commit on this branch) fixed FALSIFY-003/004/007.
Sub-agent PR #1511 (`pv lint --strict-test-binding`) surfaced a 4th
drift in this same contract:

  FALSIFY-001 cited `qwen2_0_5b_matches_hf_config`
    → does NOT exist on main.
  Actual: `qwen2_0_5b_matches_hf_config_2026_05_04`
    (date-suffix added by impl PR #1474 / commit 9af6e71 — May 4).

The earlier round-2 audit (which focused on suffix + module-path
drift) didn't catch this because the test name has a DATE-SUFFIX
drift class (function name + `_<date>` is a real Rust test, but
the contract truncated to the prefix).

Updates:
- FALSIFY-001 test ref: append `_2026_05_04` suffix.
- v1.6.0 changelog updated to record 4 fixes (was 3).
- Verified: cargo test qwen2_0_5b_matches_hf_config_2026_05_04 PASS.
- pv lint --strict-test-binding contracts/apr-pretrain-arch-polymorphic-v1.yaml: 0 PV-VER-002 (down from 4 pre-fix).

This consolidates round 2 into a single commit on the same branch
+ PR (#1509) rather than spawning a round-3 PR for one extra fix.
The lint hardening in #1511 is what made finding the 4th drift
trivial; future drift will be caught at contract-merge time once
#1511 lands.

Refs: SPEC-SHIP-TWO-001 §50.4 cascade,
      PR #1511 (sub-agent's pv lint --strict-test-binding),
      Issue #1510

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>