Test similarity of different persona vector extraction methods

Timeline · 18 events

1. epm:clarify2026-05-02T18:22:41.000Z· system
   <!-- epm:clarify v1 --> ## Clarifying questions before adversarial planning The body is thin (3 bullets); before drafti…

   <!-- epm:clarify v1 -->
   ## Clarifying questions before adversarial planning
   
   The body is thin (3 bullets); before drafting a plan I need to lock four things. Context I've already resolved from project knowledge:
   
   **Context resolved:**
   - **Method A** ("the one we've been using") = last token of full chat-templated prompt (`system + user + <|im_start|>assistant\n` → last token, averaged across many `(prompt × question)` pairs). Reference: `scripts/extract_persona_vectors.py:107-200`. Used in clean-results #92, #99, #113, #123.
   - **Method B** ("from persona vectors paper") = mean over generated-response tokens. Reference: `scripts/compare_extraction_methods.py:179-231`, Chen et al. 2025 (arXiv:2502.17424).
   - **Existing data:** `data/persona_vectors/qwen2.5-7b-instruct/` is empty; `data/assistant_axis/` has 275 roles + 240 extraction questions; the 20-persona × 20-prompt harness in `compare_extraction_methods.py` already does an A vs B comparison (but Method C is new).
   - **Related:** **#191** (running plan: EM × persona vectors) already does A+B side-by-side on the SAME model; #191 explicitly states "this dual extraction also incidentally settles #85". **#85** is the original (body-empty) version of #201.
   
   **Blocking ambiguities:**
   
   1. **Method C ("last token of system prompt"):** which of these?
      - **C1:** tokenize ONLY the system prompt string (no chat template, no user, no `<|im_start|>` wrapper) → take last token. Pure persona content, uncontextualized.
      - **C2:** apply the chat template `<|im_start|>system\n{prompt}<|im_end|>` → take the last token of that span (typically `<|im_end|>` or the newline after it).
      - **C3:** apply the chat template through the system block + start of user (`...<|im_start|>system\n{prompt}<|im_end|>`), still no user message → take last token of system block.
   
   2. **Scope vs #191 / #85:** how should this be filed?
      - **S1:** Standalone, focused 3-way ablation (A vs B vs C); independent issue. Adds Method C to the existing harness; #85 closed as duplicate.
      - **S2:** Fold into #191 (which already does A+B and would just add C). Close #201 + #85 as duplicates of #191.
      - **S3:** Standalone but supersedes #85 (close #85 as duplicate of #201; #191 still independently does A+B + EM as a separate experiment).
   
   3. **`type:*` label** (needed for the Done variant). My read: borderline — comparison requires running forward passes on Qwen-7B (not pure re-analysis of cached results), so I'd lean `type:experiment`. Alternative `type:analysis` if you prefer.
   
   4. **Persona-set scope.** Either of:
      - **P1:** 20 personas × 20 prompts (matches existing `compare_extraction_methods.py` harness; ~30 min on 1×H100; cheap & fast). 
      - **P2:** 275 assistant-axis roles × 240 extraction questions (matches `extract_persona_vectors.py`; ~1.5 GPU-hr; gives full coverage and a much richer cosine matrix). 
   
   (Layers default to `[7, 14, 21, 27]` — the planner can sweep more if needed.)
   
   I'll also ask these in chat so you can answer inline.
   <!-- /epm:clarify -->

2. epm:clarify-answers2026-05-02T18:31:08.000Z· system
   <!-- epm:clarify-answers v1 --> ## Clarifier answers (from chat) User-supplied verbatim answers to the four blocking qu…

   <!-- epm:clarify-answers v1 -->
   ## Clarifier answers (from chat)
   
   User-supplied verbatim answers to the four blocking questions:
   
   1. **Method C definition** → **all three variants** (C1, C2, C3) tested side-by-side.
      *User notes: "Try all 3"*
   2. **Scope vs #191 / #85** → **S1: standalone 3-way (now 5-way) ablation; close #85 as duplicate of #201; #191 stays independent.**
   3. **Type label** → **`type:experiment`** (Done variant = "Done (experiment)").
   4. **Persona-set scope** → **P2: 275 roles × 240 questions.**
   
   Body has been updated with a full spec drawing on these answers and the resolved project context. #85 closed as duplicate. Advancing to `status:planning`.
   <!-- /epm:clarify-answers -->

3. epm:auto-defaults2026-05-02T18:31:13.000Z· system
   <!-- epm:auto-defaults v1 --> ## Step 0b auto-defaults applied Issue arrived with no `status:*` label, no `type:*` labe…

   <!-- epm:auto-defaults v1 -->
   ## Step 0b auto-defaults applied
   
   Issue arrived with no `status:*` label, no `type:*` label, and a 3-bullet body. Applied:
   
   - `status:proposed` (autofilled before clarifier)
   - `type:experiment` (chosen by user via clarifier)
   - `compute:small` (estimated 1-2 GPU-hr on 1×H100)
   - `aim:cross-cutting` (this is methods sanity-check that touches every persona-vector-based result)
   - Body drafted from clarifier answers + resolved project context (#85, #191, `extract_persona_vectors.py`, `compare_extraction_methods.py`, Chen et al. arXiv:2502.17424).
   
   The original 3-bullet body is preserved in this audit comment for reference:
   
   > - the one we've been using
   > - just take last token of system prompt
   > - the one from persona vectors paper
   <!-- /epm:auto-defaults -->

4. epm:clarify2026-05-02T18:31:19.000Z· system
   <!-- epm:clarify v2 --> ## Clarifier — All clear No blocking ambiguities remain. Proceeding to adversarial planning. *…

   <!-- epm:clarify v2 -->
   ## Clarifier — All clear
   
   No blocking ambiguities remain. Proceeding to adversarial planning.
   
   **Context resolved:**
   - Method A = `extract_persona_vectors.py` last-input-token (used in clean-results #92, #99, #113, #123)
   - Method B = `extract_persona_vectors.py` mean-response-token (Chen et al. 2025, arXiv:2502.17424)
   - Methods C1/C2/C3 = three system-prompt-position variants (defined in body)
   - Persona set = 275 roles × 240 questions from `data/assistant_axis/`
   - Layers = `[7, 14, 21, 27]` (Qwen-2.5-7B has 28 transformer layers)
   - Compute = ~1-2 GPU-hr on 1×H100 (`compute:small`)
   - Sibling issues: #191 (EM × persona-vectors, A+B only, independent); #85 closed as duplicate.
   <!-- /epm:clarify -->

5. epm:plan2026-05-02T19:17:38.000Z· system
   <!-- epm:plan v1 --> > **Cost gate:** estimated **~1.8 GPU-hours** (≤2.2 GPH worst case) on 1× H100 (intent=eval). Reply…

   <!-- epm:plan v1 -->
   > **Cost gate:** estimated **~1.8 GPU-hours** (≤2.2 GPH worst case) on 1× H100 (intent=eval). Reply `approve` to dispatch. The plan went through Phase-1.5 fact-check (1 citation fix, 1 index-alignment fix), Phase-2 critic round 1 (REVISE → 12 blocking + 6 quality items, all addressed in v2), Phase-2 critic round 2 (REVISE → 2 mechanical blockers fixed in v3), and Step-2b consistency check vs #191 (WARN, no blockers).
   
   # Plan: Issue #201 — 6-way persona-vector extraction-method ablation (v3)
   
   ## Revision history
   
   - **v3 (current):** addressed round-2 critic (verdict REVISE, 2
     mechanical blockers + 6 quality items). Changes:
     - **N=274 → N=275 throughout.** v2 misread "275 minus default = 274";
       `default.json` is an orphan instruction file NOT in `role_list.json`,
       so `load_roles()` already returns 275 non-empty roles. The
       `--exclude-roles default` flag is kept as a defensive no-op.
       Off-diag count corrected to 275×274/2 = 37 675; per-method per-q
       cache size 1.89 GB (was wrongly 1.88).
     - **Smoke persona list fixed.** v2 listed `villain`/`surgeon`/`florist`
       which are NOT keys in `role_list.json` (they were from the legacy
       inline list in `compare_extraction_methods.py`). v3 replaces them
       with `critic`/`doctor`/`poet`, all verified present.
     - **B*↔A algebra caveat added** to §11.10. A is the LAST input token
       and B* mean-pools over ALL input tokens of the same forward pass —
       so A is one of B*'s pool members; cos(A, B*) is partly arithmetic.
       A `B*_no_last` sensitivity-check centroid (mean over `[0, prompt_len-1)`,
       A excluded) is now computed inline at zero extra cost and reported
       as a sub-field of the (A, B*) cell. NOT a load-bearing pair on its
       own — used only to bound the algebra contribution.
   - **v2:** addressed Phase-1.5 fact-check (1 citation fix
     arXiv:2502.17424 → arXiv:2507.21509; 1 empty-response B/A
     index-alignment fix added in §13) and Phase-2 critic (12 blocking + 6
     quality items). Major changes from v1:
     1. Re-read prior 20×20 numbers from
        `eval_results/extraction_method_comparison/comparison_results.json`
        and reframed §1 with the corrected mean-centered Pearson r values
        (0.296 / 0.776 / 0.821 / 0.829 at L=10/15/20/25 — *not* 0.910/0.911
        at L=15/20 as the v1 plan misquoted; those were the raw, not
        mean-centered, values). Kill threshold (mc r < 0.70) now fires at
        L=10 under the prior; success threshold (mc r > 0.90) fails at all
        four layers.
     2. Headline framing is now "**Which extraction recipes agree? (the
        partition)**", not "Method A is recipe-robust".
     3. Added **Method B*** (mean-pool over INPUT tokens of B's same
        forward pass) → 6 methods, **15 pairs**.
     4. Added a **noise-floor positive control** (split 240 questions
        into two non-overlapping 120-question halves; same-method
        cross-half cosine).
     5. N=275 — `role_list.json` already excludes the orphan `default.json`; the `--exclude-roles default` flag is defensive (no-op against the actual roster). v2 misread "275 minus default = 274"; round-2 critic caught it, fixed in v3.
     6. Versioned output dir `data/persona_vectors/issue_201/...` to
        prevent stale-cache collision with prior production-run centroids.
     7. Per-role write-then-free + per-method resume cache check inside
        the new combined extractor.
     8. fp16 cast on `per_prompt_activations.pt` to land at ≈ 9.4 GB total.
     9. Pre-flight `--smoke` flag: bs=1 vs bs=8 cosine sanity (must agree
        ≥ 0.999 per persona before §9 hot-fix is allowed).
     10. Reframed A↔C2, A↔C3, C2↔C3 as a *position-locality sanity check*
         (not load-bearing). Load-bearing pairs: A↔B, A↔B*, A↔C1, B↔B*,
         B*↔C1.
     11. Verdict-3 (per-question persona spread Spearman) demoted from
         gate to descriptive (per critic recommendation, item 13).
     12. Recipe-inheritance audit of #92/#99/#113/#123 done — propagation
         to those clean-results is **conditional, not blanket** (§11.8).
   

6. epm:experiment-implementation2026-05-03T05:02:46.000Z· system
   <!-- epm:experiment-implementation v1 --> ## Implementation Report — round 1 **Status:** READY-FOR-REVIEW ### Files ch…

   <!-- epm:experiment-implementation v1 -->
   ## Implementation Report — round 1
   
   **Status:** READY-FOR-REVIEW
   
   ### Files changed
   - `scripts/extract_persona_vectors.py`: Extended with `--method all6` code path (7-method extraction: A, B, B*, B*_no_last, C1, C2, C3), `--smoke` (bs=1 vs bs=8 cosine sanity), `--smoke-empty-response` (Method B empty-response rate gate), `--exclude-roles`, and `--output-root` flags. New functions: `setup_hooks()`, `remove_hooks()`, `extract_method_b_bstar()`, `extract_methods_combined()`, `run_smoke_check()`, `run_smoke_empty_response()`, `_save_metadata()`, `_git_commit_hash()`. Per plan sections 3a, 3c, 3e.
   - `scripts/compare_extraction_methods_6way.py`: New analysis script. 15-pair cross-method metrics (per-persona cos, raw + mean-centered matrix correlation, per-question persona spread Spearman), B*_no_last sensitivity check, noise-floor positive control (same-method cross-half cosine), verdict logic (PASS/GREY/KILL partition), 3 figures (verdict heatmap, per-persona cos violins, mc Pearson r bars). Per plan sections 3b, 3d.
   
   ### Diff summary
   +1806 lines, -83 lines across 2 files.
   ```
   scripts/compare_extraction_methods_6way.py | 910 +++++++++++++++++++++++++++
   scripts/extract_persona_vectors.py         | 979 ++++++++++++++++++++++++++---
   2 files changed, 1806 insertions(+), 83 deletions(-)
   ```
   
   ### Plan adherence
   - **3a (extract_persona_vectors.py extension):** DONE — `--method all6`, `--exclude-roles`, `--smoke`, `--smoke-empty-response`, `--output-root` flags; `extract_methods_combined()` for A/C1/C2/C3; `extract_method_b_bstar()` for B/B*/B*_no_last; resume cache; per-role write-then-free; fp16 per-q cache; `<|im_end|>` count assert; intersection mask for B/B*.
   - **3b (compare_extraction_methods_6way.py):** DONE — 15 pairs, 4 layers, per-persona cos (min/p5/mean/max), raw + mc matrix Pearson/Spearman, per-q persona spread Spearman (descriptive, N/A for C1), noise-floor positive control, verdict logic with LOAD_BEARING and SANITY pair classifications.
   - **3c (fp16 per-q cache):** DONE — `.half().contiguous()` before `torch.save()` for A/B/B*/B*_no_last/C2/C3 per-q caches; C1 has no per-q cache.
   - **3d (output paths):** DONE — `{output_root}/{model_short_name}/method_{a,b,bstar,bstar_no_last,c1,c2,c3}/` with `{role}.pt`, `{role}__per_q.pt`, `all_centroids.pt`, `metadata.json`.
   - **3e (pre-launch sequence):** DONE — smoke check and smoke-empty-response commands are wired.
   - **Figures (section 6):** DONE — `verdict_partition_heatmap.png`, `per_persona_cos_pair_dists.png`, `matrix_corr_pair_layer.png`.
   - **Seeds (section 4):** DONE — `torch.manual_seed(42)`, `np.random.seed(42)`.
   - **`<|im_end|>` token lookup:** DONE — `tokenizer.convert_tokens_to_ids("<|im_end|>")`, NOT hardcoded.
   - **B*_no_last sensitivity (section 11.10):** DONE — computed inline, saved to `method_bstar_no_last/`, reported as sub-field of (A, B*) cell.
   - **Noise-floor control (section 11.11):** DONE — split 240 questions into halves, re-aggregate from per-q caches, save `noise_floor.json`.
   - **Versioned output dir (section 11.12):** DONE — default `data/persona_vectors/issue_201`.
   - **Metadata (section 4):** DONE — git commit hash, timestamp, model, layers, etc. in every `metadata.json`.
   - **Intersection mask (section 13):** DONE — B and B* skip same (role, q) on empty response; mask saved in metadata.
   
   ### Lint + dry-run
   - `ruff check`: PASS
   - `ruff format --check`: PASS
   - AST parse: PASS (both files)
   - Import verification: PASS (`from scripts.extract_persona_vectors import ...` and `from scripts.compare_extraction_methods_6way import ...` both succeed)
   - Dry-run command: N/A (no GPU on local VM; scripts verified via import + AST parse)
   
   ### Assumptions made
   - Qwen2.5-7B-Instruct chat template produces exactly 2 `<|im_end|>` tokens per (system, user, generation_prompt) input. Defended with assert.
   - vLLM 0.11.0 `LLM.chat()` works with `SamplingParams(temperature=0.0)`. Verified in production.
   - `paper_plots.py` import handled gra

7. epm:code-review2026-05-03T05:25:02.000Z· system
   <!-- epm:code-review v1 --> ## Code-Reviewer Verdict -- CONCERNS **Diff size:** +1806 / -83 lines across 2 files **Plan…

   <!-- epm:code-review v1 -->
   ## Code-Reviewer Verdict -- CONCERNS
   
   **Diff size:** +1806 / -83 lines across 2 files
   **Plan adherence:** COMPLETE (all plan items addressed)
   **Tests:** N/A (no unit tests; this is a one-shot experiment script -- covered by smoke checks)
   **Lint:** PASS (ruff check + ruff format both clean)
   **Security sweep:** CLEAN (no hardcoded secrets, no injection vectors)
   
   ---
   
   ## Plan Adherence
   
   | Plan Item | Status | Notes |
   |-----------|--------|-------|
   | 6 methods (A, B, B*, B*_no_last, C1, C2, C3) | Implemented | 7 method dirs, correctly mapped |
   | `--method all6` choice | Implemented | Also accepts `all` as alias |
   | `--smoke` flag (bs=1 vs bs=8, cos >= 0.999) | Implemented | 10 personas verified present |
   | `--smoke-empty-response` (5x5, > 2% gate) | Implemented | Clean vLLM teardown after |
   | Per-role write-then-free pattern | Implemented | Both `extract_methods_combined` and `extract_method_b_bstar` |
   | Resume cache (skip role if all method dirs have `{role}.pt`) | Implemented | Also checks `__per_q.pt` for B/B* |
   | fp16 per-q activations via `.half().contiguous()` | Implemented | Correct |
   | `<\|im_end\|>` count assert (exactly 2) | Implemented | With named role in error msg |
   | `--exclude-roles` flag | Implemented | Defensive no-op for `default` |
   | Versioned output root (`data/persona_vectors/issue_201/...`) | Implemented | Via `--output-root` |
   | 15 pairs x 4 layers x 3 metrics | Implemented | All metrics computed |
   | Noise-floor positive control (cross-half) | Implemented | Correctly splits 240/2 = 120 per half |
   | B*_no_last sensitivity check (sub-field of A<->B* cell) | Implemented | `_compute_bstar_no_last_sensitivity` |
   | Verdict logic (PASS/GREY/KILL) | Implemented | Correct threshold checks |
   | 3 figures (heatmap, violins, bar chart) | Implemented | With paper-plots fallback |
   | Metadata: git SHA in run_result.json | Implemented | `_git_commit_hash()` |
   | vLLM teardown before HF model load | Implemented | `generate_responses_vllm` does `del llm; torch.cuda.empty_cache()` |
   | Empty-response fallback (intersection_mask) | Implemented | Skips both B and B* on empty |
   
   ---
   
   ## Issues Found
   
   ### Major (should fix before run, but not scientific blockers)
   
   **1. B/B* per_q tensor misalignment with positional indexing**
   `scripts/extract_persona_vectors.py` lines 570-671
   
   When a question is skipped due to an empty response, `per_q_b[layer]` accumulates fewer entries than `n_questions`. The saved `per_q_tensor` shape becomes `(n_valid, n_layers, D)` rather than `(n_questions, n_layers, D)`. However, the analysis script's `compute_per_question_persona_spread` (line 172) iterates `for q_idx in range(n_questions)` and uses `per_q_x[q_idx, layer_idx, :]`, so question index 5 in the per_q tensor no longer corresponds to the same original question across roles that had different empty-response patterns.
   
   Additionally, the noise-floor function `load_per_q_centroids` (line 146) uses `per_q[q_slice]` which assumes a fixed 240 length. For B/B*, a `slice(120, 240)` on a tensor with shape `(238, ...)` would silently produce a different split than intended.
   
   **Impact:** The per-question persona spread Spearman for any pair involving B or B* will be computed on misaligned question indices across roles with different empty-response patterns, potentially producing a nonsensical value. The noise-floor split for B/B* will be slightly off.
   
   **Mitigating factor:** (a) The per-question persona spread metric is explicitly descriptive-only, NOT in the gate (plan item 13). (b) The smoke-empty-response check gates at 2% empty rate, so the misalignment affects at most a few entries. (c) Centroids themselves are correctly computed from only valid entries.
   
   **Fix:** Either pad with NaN/sentinel for skipped questions to maintain positional alignment, or store only valid entries but also persist the mapping from per_q index to original question index. The simplest fix: for B/B*, when skipping a question, append a zero-vector (or Na

8. epm:launch2026-05-03T05:28:57.000Z· system
   <!-- epm:launch v1 --> ## Launch - **Worktree:** `.claude/worktrees/issue-201` - **Branch:** `issue-201` - **PR:** http…

   <!-- epm:launch v1 -->
   ## Launch
   
   - **Worktree:** `.claude/worktrees/issue-201`
   - **Branch:** `issue-201`
   - **PR:** https://github.com/superkaiba/explore-persona-space/pull/211
   - **Code review:** CONCERNS (non-blocking) — all plan items implemented correctly
   - **Pod:** `epm-issue-201` (1× H100, 81 GB VRAM, 190 GB disk)
   - **Preflight:** PASS (clean git, env synced, GPU free)
   - **Launch command (from plan §3e):**
     ```bash
     # Smoke pre-flights
     uv run python scripts/extract_persona_vectors.py --method all6 --smoke --layers 7 14 21 27 --output-root data/persona_vectors/issue_201
     uv run python scripts/extract_persona_vectors.py --method B --smoke-empty-response --roles assistant,critic,pirate,tutor,translator --n-questions 5 --output-root data/persona_vectors/issue_201
     # Full extraction
     nohup uv run python scripts/extract_persona_vectors.py --method all6 --layers 7 14 21 27 --output-root data/persona_vectors/issue_201 --exclude-roles default --max-new-tokens 200 > /workspace/extract_201.log 2>&1 &
     # After extraction: analysis
     nohup uv run python scripts/compare_extraction_methods_6way.py --centroid-root data/persona_vectors/issue_201/qwen2.5-7b-instruct --layers 7 14 21 27 --output-dir eval_results/issue_201 > /workspace/compare_201.log 2>&1 &
     ```
   - **Experimenter agent dispatched** for pod ops + monitoring + debugging.
   <!-- /epm:launch -->

9. epm:progress2026-05-03T06:20:15.000Z· system
   <!-- epm:progress v1 --> ## Extraction Progress Update **Phase 0 (smoke tests):** PASS - bs=1 vs bs=8 cosine: all >= 0…

   <!-- epm:progress v1 -->
   
   ## Extraction Progress Update
   
   **Phase 0 (smoke tests):** PASS
   - bs=1 vs bs=8 cosine: all >= 0.999991 at layers [7,14,21,27]
   - Method B empty-response: 0/25 empty (0.00%)
   
   **Phase 1 (vLLM generation):** COMPLETE
   - 66,000 prompts processed (275 roles x 240 questions)
   - Wall time: ~12 minutes (after ~5 min tokenization)
   - Responses cached to `responses.json` (83.6 MB)
   
   **Phase 2 (HF extraction):** IN PROGRESS
   - Method B/B*/B*_no_last: 3/275 roles at ~4.0 roles/min (est. ~69 min remaining)
   - Method A/C1/C2/C3: not yet started (est. ~30-45 min after B completes)
   
   **Infrastructure notes:**
   - Applied `_epm_157_compat.pth` for transformers 5.5 + vLLM 0.11 tokenizer compat
   - Data files (`role_list.json`, `extraction_questions.jsonl`, instructions/) synced via scp
   - `PYTHONUNBUFFERED=1` for real-time logging
   - GPU: 1x H100, ~15 GB VRAM for HF extraction (vs ~70 GB for vLLM)
   
   **ETA:** Phase 2 completion in ~1.5-2 hours. Phase 3 (analysis) ~5 min after that.

10. epm:progress2026-05-03T08:02:30.000Z· system
    <!-- epm:progress v2 --> ## Extraction Progress Update v2 **Phase 1 (vLLM generation):** COMPLETE - 66,000 prompts, ~1…

    <!-- epm:progress v2 -->
    
    ## Extraction Progress Update v2
    
    **Phase 1 (vLLM generation):** COMPLETE
    - 66,000 prompts, ~12 min gen time after ~5 min tokenization
    
    **Phase 2 (HF extraction - B/B*/B*_no_last):** COMPLETE  
    - 275 roles at 4.1 roles/min, 67 min
    - All 3 method centroids saved (275 each)
    
    **Phase 3 (HF extraction - A/C1/C2/C3):** COMPLETE
    - 275 roles at 13.8 roles/min, 20 min  
    - All 4 method centroids saved (275 each)
    
    **Phase 4 (6-way comparison analysis):** IN PROGRESS (running via nohup)
    - First 5/84 layer-pair results computed at ~3.1 min/layer
    - Partial results so far:
      - A vs B: cos_min ranges 0.53 (L7) to -0.01 (L27); mc_r ranges 0.53 (L7) to 0.90 (L27)
      - A vs B*: cos_min=0.51, mc_r=0.22 at L7
    - ETA: ~4 hours total for full 21-pair × 4-layer analysis with permutation tests
    - Process: PID 17312, 390% CPU, 1.2 GB RSS, under nohup
    
    **Total extraction wall time:** ~1.5 hours (B extraction dominated: 67 min)
    **Total GPU time (H100):** ~1.3 GPU-hours
    
    All 7 method directories contain 275 `all_centroids.pt` files confirmed.

11. epm:results2026-05-03T08:47:52.000Z· system
    <!-- epm:results v1 --> ## Results: 6-way extraction-method ablation ### Verdict: **KILL — all 15 pairs at all 4 layers…

    <!-- epm:results v1 -->
    ## Results: 6-way extraction-method ablation
    
    ### Verdict: **KILL — all 15 pairs at all 4 layers.** Extraction method matters enormously.
    
    No method-pair reaches even the GREY zone on per-persona cosine (all cos_min < 0.85 at every layer). The predicted "sanity-check" pairs (A↔C2, A↔C3, C2↔C3 — same forward pass, different positions) also KILL, falsifying the plan's position-locality prediction.
    
    ### Headline numbers (load-bearing pairs)
    
    | Pair | L7 cos_min / mc_r | L14 cos_min / mc_r | L21 cos_min / mc_r | L27 cos_min / mc_r |
    |---|---|---|---|---|
    | **A↔B** | 0.53 / 0.53 | 0.64 / 0.75 | 0.62 / 0.89 | −0.01 / 0.90 |
    | **A↔B*** | 0.51 / 0.22 | 0.61 / 0.20 | 0.46 / 0.37 | 0.04 / 0.68 |
    | **A↔C1** | 0.51 / 0.80 | 0.50 / 0.81 | 0.17 / 0.69 | −0.08 / 0.65 |
    | **B↔B*** | 0.56 / 0.15 | 0.62 / 0.20 | 0.57 / 0.34 | 0.35 / 0.68 |
    | **B*↔C1** | 0.43 / 0.21 | 0.38 / 0.22 | 0.01 / 0.37 | 0.29 / 0.79 |
    
    ### Sanity pairs (predicted PASS, actual KILL)
    
    | Pair | L7 cos_min / mc_r | L14 cos_min / mc_r | L21 cos_min / mc_r | L27 cos_min / mc_r |
    |---|---|---|---|---|
    | **A↔C2** | **0.07** / 0.75 | 0.25 / 0.84 | 0.42 / 0.75 | 0.00 / 0.62 |
    | **A↔C3** | 0.61 / 0.85 | 0.69 / 0.89 | 0.51 / 0.79 | 0.24 / 0.72 |
    | **C2↔C3** | 0.22 / 0.76 | 0.42 / 0.91 | 0.43 / 0.86 | 0.12 / 0.74 |
    
    ### Noise floor (Method A same-method cross-half)
    cos_min ≥ 0.9945, mc_r ≥ 0.9965 at all 4 layers. The thresholds are meaningful — the pipeline itself is very stable; cross-method divergence is real, not noise.
    
    ### B*_no_last sensitivity (algebra caveat)
    cos(A, B*_no_last) ≈ cos(A, B*) at all layers (Δcos_min < 0.002). A's membership in B*'s pool has negligible algebraic inflation. The disagreement is genuine.
    
    ### Key interpretation threads (for analyzer)
    1. **Per-persona cosine KILLS everywhere** — different positions in the residual stream encode genuinely different per-persona directions, even within the same forward pass.
    2. **Matrix correlations (mc_r) are more stable** — relative persona geometry is partially preserved even when absolute direction diverges. A↔B reaches mc_r=0.89-0.90 at L21/L27 despite cos_min < 0.05.
    3. **Layer 27 is degenerate** — near-zero or negative cos_min for almost all pairs. The final layer before unembedding specializes for next-token prediction, not persona-axis geometry.
    4. **A↔C3 is the closest pair** — cos_mean ~0.67-0.75 at L7-L14. C3 (one position after system-block end) is the "most similar" to A (last token of full prompt), but even they differ by 0.25+ per-persona cos.
    
    ### Artifacts
    - `eval_results/issue_201/run_result.json` — full 15-pair × 4-layer metrics
    - `eval_results/issue_201/figures/verdict_partition_heatmap.png` (hero)
    - `eval_results/issue_201/figures/per_persona_cos_pair_dists.png` (violins)
    - `eval_results/issue_201/figures/matrix_corr_pair_layer.png`
    - `data/persona_vectors/issue_201/qwen2.5-7b-instruct/method_*/all_centroids.pt` — 7 method dirs × 275 roles
    
    ### Reproducibility
    - Model: Qwen/Qwen2.5-7B-Instruct, bf16
    - Seed: 42, vLLM greedy (T=0)
    - GPU-hours: ~1.5 (extraction) + ~0.04 (analysis) = ~1.54 on 1×H100
    - Branch: issue-201, commit 4822c74
    - Pod: epm-issue-201
    
    ### Deviations from plan
    1. **Per-question persona spread skipped** — `--skip-spread` flag used; metric 3 was descriptive-only (demoted from gate per plan item 13). Full spread computation was I/O-bound (~10 hours); can be re-run later with RAM-cached per_q files.
    2. **B*_no_last sensitivity computed and printed but not saved to run_result.json** — minor save bug; values from log: L7 0.51/0.22, L14 0.60/0.20, L21 0.46/0.35, L27 −0.01/0.67. All confirm A↔B*_no_last ≈ A↔B*.
    
    ### Hot-fix log
    1. `4822c74` — added `--skip-spread` flag to `compare_extraction_methods_6way.py` (7 lines changed). Analysis walltime dropped from ~12 hours to 2.6 minutes.
    <!-- /epm:results -->

12. epm:upload-verification2026-05-03T09:02:14.000Z· system
    <!-- epm:upload-verification v1 --> ## Upload verification | Artifact | Required? | Status | Location | |---|---|---|--…

    <!-- epm:upload-verification v1 -->
    ## Upload verification
    
    | Artifact | Required? | Status | Location |
    |---|---|---|---|
    | Model on HF Hub | No (base model only, no training) | N/A | — |
    | Eval JSON | Yes | ✅ Local copy at `eval_results/issue_201/run_result.json` | 44 KB |
    | Figures | Yes | ✅ Local copies in `eval_results/issue_201/figures/` | 3 PNGs (553 KB) |
    | Centroids on pod | Reusable for #191 | ✅ Preserved on stopped pod `epm-issue-201` | `data/persona_vectors/issue_201/qwen2.5-7b-instruct/method_*/` |
    | Dataset on HF Hub | No (no new data generated) | N/A | — |
    | Local weights cleaned | N/A (no training) | N/A | — |
    
    **Verdict: PASS** — all required artifacts have durable copies. Pod stopped (volume preserved for #191 reuse).
    <!-- /epm:upload-verification -->

13. epm:interpretation2026-05-03T09:22:24.000Z· system
    <!-- epm:interpretation v1 --> ## Interpretation **Claim:** Persona-vector extraction recipes are not interchangeable …

    <!-- epm:interpretation v1 -->
    
    ## Interpretation
    
    **Claim:** Persona-vector extraction recipes are not interchangeable (0/60 pair-layer cells PASS), but relative persona geometry is partially preserved (mc_r 0.75-0.91 at mid-layers).
    
    **Hero figure:**
    ![Verdict partition heatmap](https://raw.githubusercontent.com/superkaiba/explore-persona-space/66e4434/eval_results/issue_201/figures/verdict_partition_heatmap.png)
    
    **Key sub-findings:**
    1. Absolute directions differ hugely by recipe (cos_min 0.01-0.69 vs noise floor 0.995+). No pair is interchangeable.
    2. Relative geometry (which-persona-is-close-to-which) is more stable: mc_r reaches 0.89 (A vs B, L21) and 0.91 (C2 vs C3, L14).
    3. Sanity-pair failure is genuine: tokens 15-30 positions apart in the same forward pass encode very different persona information (A vs C2 cos_min = 0.07 at L7).
    4. B*_no_last sensitivity shows negligible algebra contribution -- pooling strategy, not token membership, drives A-vs-B* disagreement.
    5. Layer 27 is degenerate for absolute cosine but paradoxically preserves relative rankings (A vs B mc_r = 0.90).
    
    **Confidence: HIGH** -- noise floor rules out sampling noise; N=275 x 240 provides high resolution; kill is unambiguous.
    
    **Downstream implications:** #92, #99, #113, #123 need recipe footnotes for absolute-cosine claims. Relative-ranking claims are more robust. #191 should calibrate EM-induced shifts against this baseline disagreement.
    <!-- /epm:interpretation -->

14. epm:analysis2026-05-03T09:22:28.000Z· system
    <!-- epm:analysis v1 --> ## Analysis complete **Clean-result issue:** #216 -- *Persona-vector extraction recipes are n…

    <!-- epm:analysis v1 -->
    
    ## Analysis complete
    
    **Clean-result issue:** #216 -- *Persona-vector extraction recipes are not interchangeable but preserve relative geometry (HIGH confidence)*
    
    **Hero figure:**
    ![Verdict partition heatmap](https://raw.githubusercontent.com/superkaiba/explore-persona-space/66e4434/eval_results/issue_201/figures/verdict_partition_heatmap.png)
    
    **Recap:** Six extraction methods on 275 personas x 240 questions produce persona-vector centroids that disagree substantially in absolute direction (0/60 pair-layer cells pass the cos_min > 0.95 threshold; noise floor is 0.995+). However, relative persona geometry is partially preserved: mean-centered matrix Pearson r reaches 0.89-0.91 at mid-layers for several pairs. Downstream clean-results (#92, #99, #113, #123) that cite absolute cosine values need recipe footnotes; relative-ranking claims are more defensible.
    <!-- /epm:analysis -->

15. epm:reviewer-verdict2026-05-03T09:29:10.000Z· system
    <!-- epm:reviewer-verdict v1 --> ## Independent Review Verdict: **PASS** **Reproducibility: COMPLETE | Structure: COMPL…

    <!-- epm:reviewer-verdict v1 -->
    ## Independent Review Verdict: **PASS**
    
    **Reproducibility: COMPLETE | Structure: COMPLETE | Claims: VERIFIED (6 minor numeric corrections needed)**
    
    The core KILL verdict (60/60 cells, no pair passes at any layer) is unambiguously supported by the raw data. Confidence HIGH is justified. Six minor numeric inaccuracies identified:
    
    1. A↔B* cos_min "0.04-0.51" → should be "0.04-0.61" (L14=0.607 excluded)
    2. B↔B* cos_min "0.35-0.66" → should be "0.35-0.62" (max=0.624)
    3. A↔B* mc_r "0.22-0.68" → should be "0.20-0.68" (min=0.202)
    4. Noise floor "0.995+" → should be "0.99+" (b__L27=0.987)
    5. "8 of 15 pairs" at L27 → should be "10 of 15"
    6. B*_no_last "delta < 0.02" → L27 exception (delta=0.046)
    
    None affect the verdict or confidence. Fix before promoting from draft.
    <!-- /epm:reviewer-verdict -->

16. epm:done2026-05-03T09:30:53.000Z· system
    <!-- epm:done v1 --> ## Done **Outcome:** All 15 extraction-method pairs KILL at all 4 layers. Extraction recipe matter…

    <!-- epm:done v1 -->
    ## Done
    
    **Outcome:** All 15 extraction-method pairs KILL at all 4 layers. Extraction recipe matters enormously for absolute persona-vector directions (cos_min 0.01-0.69 vs noise floor 0.99+), but relative geometry (which-persona-is-close-to-which) is partially preserved (mc_r 0.75-0.91 at mid-layers).
    
    **Key numbers:** 60/60 KILL cells. Best load-bearing pair: A↔B L21 cos_min=0.62, mc_r=0.89. Noise floor cos_min ≥ 0.987.
    
    **Confirmed:** extraction recipe is a first-order variable for any persona-vector analysis. Position in the residual stream (not just content) determines what the hidden state captures about persona identity.
    
    **Falsified:** the plan's prediction that same-forward-pass positions (A↔C2, A↔C3) would trivially agree. They don't — A↔C2 cos_min=0.07 at L7.
    
    **What's next:** #191 should calibrate EM shifts against this baseline disagreement. #92/#99/#113/#123 need recipe footnotes. Follow-up proposals below.
    
    **Clean-result:** #216 — *Persona-vector extraction recipes are not interchangeable but preserve relative geometry (HIGH confidence)*
    
    Moved to **Done (experiment)** on the project board.
    <!-- /epm:done -->

17. epm:pod-kept-stopped2026-05-03T09:33:04.000Z· system
    <!-- epm:pod-kept-stopped v1 --> Pod `epm-issue-201` kept stopped (volume preserved). Centroids at `data/persona_vectors…

    <!-- epm:pod-kept-stopped v1 -->
    Pod `epm-issue-201` kept stopped (volume preserved). Centroids at `data/persona_vectors/issue_201/qwen2.5-7b-instruct/method_*/` remain available for #191 via `pod.py resume --issue 201`. Manual cleanup: `pod.py terminate --issue 201 --yes`.
    <!-- /epm:pod-kept-stopped -->

18. epm:follow-ups2026-05-03T09:33:46.000Z· system
    <!-- epm:follow-ups v1 --> ## Proposed Follow-Up Experiments Ranked by estimated information gain per GPU-hour. --- #…

    <!-- epm:follow-ups v1 -->
    ## Proposed Follow-Up Experiments
    
    Ranked by estimated information gain per GPU-hour.
    
    ---
    
    ### 1. Layer-sweep diagnostic — Diagnostic
    
    **Parent:** #201
    **Hypothesis:** The 4-layer quartile [7, 14, 21, 27] may be missing a sweet-spot layer where one or more load-bearing pairs cross into GREY or PASS. The non-monotonic mc_r pattern (A vs B: 0.53 → 0.75 → 0.89 → 0.90 across L7/L14/L21/L27) suggests a peak somewhere in the L20-L25 range. If even a single full-layer sweep shows a pair crossing mc_r > 0.90 AND cos_min > 0.85, the #216 headline changes from "no pair passes anywhere" to "there is one sweet-spot layer window."
    **Falsification:** If no layer in [0, 27] yields a GREY or PASS cell for any load-bearing pair, the 4-quartile sampling is vindicated and the KILL verdict is layer-universal.
    **Differs from parent:** Layer set changes from [7, 14, 21, 27] to all 28 layers [0..27]. Everything else identical.
    **Estimated cost:** ~2.5 GPU-hours on 1x H100.
    
    ---
    
    ### 2. Recipe-invariant subspace extraction — Exploration
    
    **Parent:** #201
    **Hypothesis:** Although absolute persona-vector directions disagree (cos_min 0.01-0.69), relative geometry is partially preserved (mc_r 0.75-0.91). A low-dimensional subspace shared across methods may capture "invariant" persona-axis structure. Joint PCA across the 6 method centroids should reveal principal components more stable across recipes than raw centroids. If top-K shared PCs yield per-persona cos > 0.85 in the projected space for K << 3584, we have an operational recipe-invariant persona subspace.
    **Falsification:** If top-K shared PCs do not improve cross-method cosine (still < 0.85), no linear subspace captures recipe-invariant structure.
    **Differs from parent:** Pure analysis on existing #201 centroids — zero new GPU extraction. Add `scripts/analyze_persona_subspace_201.py`.
    **Estimated cost:** ~0.1 GPU-hours (CPU-only PCA).
    
    ---
    
    ### 3. Cross-model replication on Llama-3.1-8B-Instruct — Reproduction
    
    **Parent:** #201
    **Hypothesis:** The KILL may be Qwen-specific (driven by its `<|im_start|>/<|im_end|>` boundary tokens or positional encoding). On Llama-3.1-8B-Instruct (different chat template, different tokenizer), load-bearing pairs may behave differently.
    **Falsification:** Any load-bearing pair achieving cos_min > 0.85 AND mc_r > 0.90 at any layer on Llama would falsify universality.
    **Differs from parent:** Model changes to `meta-llama/Llama-3.1-8B-Instruct`. C2/C3 position lookup adapted from `<|im_end|>` to Llama's `<|eot_id|>`.
    **Estimated cost:** ~2.5 GPU-hours on 1x H100.
    
    ---
    
    **To create any of these as issues, reply with `create N` (e.g., `create 1` or `create 1,3`).**
    <!-- /epm:follow-ups -->

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