ci(rust-test): debuginfo=0 on the test job — link-footprint relief (TD-CI-COVERAGE-MOLD-1)

The `test` job has begun hitting the same disk/RSS link cliff already
mitigated on `test-with-coverage` (b56bb2c): `ld terminated with signal 7
[Bus error]` + an LLVM crash at the `cargo test --no-run` link step of
test_sql_query / intervene_counterfactual.

Root cause is link-footprint growth, NOT a logic break (a layout break would
fail an assertion, not SIGBUS at link). PR #507 (0c6ef02, +4055 lines across
causal-edge ce64-v2 layout + cognitive-shader-driver MailboxSoaOwner /
SurrealMailboxView) grew the integration-test object set enough to tip the
previously-marginal `test`-job link over the same ceiling. It surfaced on the
first full-workspace CI run after #507 (the intervening PRs are
root-excluded crates, so their CI never linked the post-#507 tree).

Fix: give the `test` job a job-level RUSTFLAGS with `-C debuginfo=0` (parity
with the coverage job). debuginfo carries no value in CI (no debugger is
attached); dropping it cut the coverage job's per-binary link ~930 MB -> ~252 MB
(-73%, measured in b56bb2c) and relieves both the mold/GNU-ld RSS and the disk
ceiling. mold is already installed on this job. Side effect: the job gets its
own Swatinem cache key (first run repopulates).

This is a fence (buys headroom), not a root reduction of #507's legitimate
codegen — documented as such in the TD-CI-COVERAGE-MOLD-1 ledger addendum,
including the secular-growth caveat and the separate (warns-not-fails)
intervene_counterfactual.rs deprecated-API debt.

Author: claude

.claude/board/TECH_DEBT.md

@@ -147,6 +147,38 @@ timing-race hypothesis (read the actual `cargo llvm-cov` log with a scoped token
 Cross-ref: `.github/workflows/rust-test.yml` (test job mold step vs coverage job);
 `bindspace-singleton-to-mailbox-soa-v1` (the migration this is NOT).
 
+**2026-06-16 addendum — the `test` job now hits the SAME cliff; fix extended to
+it (branch `claude/ci-test-job-debuginfo0`).** The cliff this entry called out as
+*"a 2/50 intermittent"* on the coverage job has now surfaced on the **plain
+`test`** job: `ld terminated with signal 7 [Bus error]` + an LLVM crash dump at
+the `cargo test --no-run` link step of `test_sql_query` / `intervene_counterfactual`.
+Root-caused to a **link-footprint growth, not a logic break** (a layout break would
+fail an assertion, not SIGBUS at link): **PR #507** (`0c6ef02c`, +4055/−1048 across
+`causal-edge` edge.rs/layout.rs — the ce64-v2 layout — and `cognitive-shader-driver`
+mailbox_soa.rs/driver.rs/planner_bridge.rs — MailboxSoaOwner + SurrealMailboxView,
+D-PG-6) grew the object-file set linked by the lance-graph integration tests enough
+to tip the previously-marginal `test`-job link over the same disk/RSS ceiling. It
+surfaced on the first full-workspace CI run *after* #507 (the two PRs between, #509
+and the perturbation-sim #511, are root-`exclude`d so their CI never linked the
+post-#507 tree — which is why this is "the first failing PR" yet not its fault).
+**This is a FENCE, not a root reduction:** it does not shrink #507's legitimate
+codegen; it removes the dead `debuginfo=1` weight (CI never opens a debugger) to
+buy headroom — exactly the b56bb2cd lever, now applied to the `test` job. **Fix:**
+job-level `RUSTFLAGS: "-C debuginfo=0 -C target-cpu=x86-64-v3"` on `test` (parity
+with `test-with-coverage`; mold already installed). Side effect: the `test` job
+gets its own Swatinem cache key (first run repopulates). **Confirm** on the next
+green `test` run. **Residual debt if it recurs after this:** the footprint is on a
+secular upward trend (every cognitive-layer PR adds codegen) — the durable fix is a
+bigger runner or splitting the integration-test link set, not repeatedly shaving
+flags. Separately, #507 left `intervene_counterfactual.rs:133/165` calling the
+**deprecated** `CausalEdge64::inference_type()` (the consumer-migration commit
+`8131c480` lives on the unmerged `claude/continue-ndarray-x0Oaw`) — that WARNS, does
+not fail (v1 default routes through the canonical mapping per I-LEGACY-API-FEATURE-
+GATED); tracked here as a separate latent item, not fixed on this CI branch.
+Cross-ref: `.github/workflows/rust-test.yml` (now both jobs at `debuginfo=0`); PR
+#507 (`0c6ef02c`); `claude/continue-ndarray-x0Oaw` (the pending ce64-v2 consumer
+migration).
+
 ### TD-UNBUNDLE-FROM-1 — `unbundle_from` is NOT the inverse of `bundle_into` (2026-06-07)
 
 **Open.** `crates/lance-graph-planner/src/cache/kv_bundle.rs` — `unbundle_from`

.github/workflows/rust-test.yml

@@ -29,6 +29,22 @@ jobs:
   test:
     runs-on: ubuntu-24.04
     timeout-minutes: 30
+    env:
+      # Override the workflow-level debuginfo=1 for this job too (parity with
+      # test-with-coverage, TD-CI-COVERAGE-MOLD-1). The `test` job links the
+      # full lance+datafusion integration-test set at the SAME disk/RSS cliff
+      # the coverage job hit — and #507 (+4055 lines across causal-edge +
+      # cognitive-shader-driver: ce64-v2 layout + MailboxSoaOwner/
+      # SurrealMailboxView) grew that link footprint enough to tip the
+      # previously-marginal link into a hard `ld` SIGBUS (signal 7 = object
+      # file truncated when the runner partition fills mid-link). debuginfo=1
+      # carried no value here (CI never opens a debugger); dropping it cut the
+      # coverage job's per-binary link from ~930 MB to ~252 MB (-73%, measured
+      # in b56bb2cd) and relieves BOTH ceilings (mold/GNU-ld RSS + disk). mold
+      # is already installed below. Note: a job-level RUSTFLAGS gives this job
+      # its own Swatinem cache key — the first run after this change
+      # repopulates the test cache.
+      RUSTFLAGS: "-C debuginfo=0 -C target-cpu=x86-64-v3"
     defaults:
       run:
         working-directory: lance-graph