Add clean gradient check: independent Python process per method, GPU 1

Clean results (each method in fresh Python process):
BP: mean_norm=2.58e-04, s(1e-6)=98% — CONFIRMED
DFA: layer 0 = 2.86e-07 (1.2%), layers 1-3 ≈ 2.4e-09 (0%)
SB: layer 0 = 6.13e-06 (86%), layers 1-3 ≈ 1e-09 (0%)
CB: layer 0 = 6.33e-07 (18%), layers 1-3 ≈ 5e-10 (0%)

Method A (autograd.grad) and Method B (retain_grad) give identical results.
Previous 1e-12 results were caused by Python process state pollution in combined scripts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

4 files changed, 296 insertions, 0 deletions

diff --git a/results/confirmatory/clean_grads/bp_s42.json b/results/confirmatory/clean_grads/bp_s42.json
new file mode 100644
index 0000000..a82a9e7
--- /dev/null
+++ b/results/confirmatory/clean_grads/bp_s42.json
@@ -0,0 +1,74 @@
+{
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+  "batch_size": 256,
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+}
\ No newline at end of file
diff --git a/results/confirmatory/clean_grads/credit_bridge_s42.json b/results/confirmatory/clean_grads/credit_bridge_s42.json
new file mode 100644
index 0000000..e0760a6
--- /dev/null
+++ b/results/confirmatory/clean_grads/credit_bridge_s42.json
@@ -0,0 +1,74 @@
+{
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+  "batch_size": 256,
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+}
\ No newline at end of file
diff --git a/results/confirmatory/clean_grads/dfa_s42.json b/results/confirmatory/clean_grads/dfa_s42.json
new file mode 100644
index 0000000..5148d18
--- /dev/null
+++ b/results/confirmatory/clean_grads/dfa_s42.json
@@ -0,0 +1,74 @@
+{
+  "method": "dfa",
+  "seed": 42,
+  "batch_size": 256,
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+}
\ No newline at end of file
diff --git a/results/confirmatory/clean_grads/state_bridge_s42.json b/results/confirmatory/clean_grads/state_bridge_s42.json
new file mode 100644
index 0000000..49f61ff
--- /dev/null
+++ b/results/confirmatory/clean_grads/state_bridge_s42.json
@@ -0,0 +1,74 @@
+{
+  "method": "state_bridge",
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+  "batch_size": 256,
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\ No newline at end of file