Pin jax to 0.11.0 in the three execution-* workflows

The 2026-08-19 pin (#617) covered cache.yml, ci.yml and publish.yml, but
this repo has six workflows that install jax. execution-linux.yml,
execution-osx.yml and execution-win.yml install "jax[CPU]" unpinned and
build with `jb build lectures -W --keep-going`, which executes every
lecture -- so jax 0.11.1 fails them on CellTimeoutError in
numpy_vs_numba_vs_jax.

execution-linux.yml runs on a daily cron and has been red since
2026-08-18: run 32152771492 (08-18) and run 32268416676 (08-19,
head_sha 915bfd9, i.e. after #617 merged) both log "Successfully
installed jax-0.11.1 jaxlib-0.11.1" and then CellTimeoutError at the
600s myst-nb timeout. The 08-16 run resolved jax 0.11.0 and executed the
same lecture in 4.35 seconds.

Pinning jax alone is sufficient: jax 0.11.0's metadata carries
Requires-Dist: jaxlib<=0.11.0,>=0.11.0, and the pairing is additionally
enforced at import in both directions, so jaxlib cannot drift.

Closes #619

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: mmcky

.github/workflows/execution-linux.yml

@@ -31,7 +31,14 @@ jobs:
       - name: Install Jax [CPU]
         shell: bash -l {0}
         run: |
-          pip install "jax[CPU]"
+          # Pinned: jax 0.11.1 (2026-08-17) regresses XLA:CPU execution --
+          # numpy_vs_numba_vs_jax's lax.fori_loop and lax.scan cells go
+          # quadratic in n, so this -W build dies on CellTimeoutError. Matches
+          # the pin already in cache/ci/publish.yml; evidence and the exposure
+          # map are recorded in QuantEcon/workspace-lectures#49. With jax
+          # already present, the lecture's unpinned `!pip install quantecon
+          # jax` cell is satisfied and does not upgrade.
+          pip install "jax[CPU]==0.11.0"
       - name: Build Lectures (+ Execution Checks)
         shell: bash -l {0}
         run: jb build lectures --path-output=./ -W --keep-going

.github/workflows/execution-osx.yml

@@ -31,7 +31,14 @@ jobs:
       - name: Install Jax [CPU]
         shell: bash -l {0}
         run: |
-          pip install "jax[CPU]"
+          # Pinned: jax 0.11.1 (2026-08-17) regresses XLA:CPU execution --
+          # numpy_vs_numba_vs_jax's lax.fori_loop and lax.scan cells go
+          # quadratic in n, so this -W build dies on CellTimeoutError. Matches
+          # the pin already in cache/ci/publish.yml; evidence and the exposure
+          # map are recorded in QuantEcon/workspace-lectures#49. With jax
+          # already present, the lecture's unpinned `!pip install quantecon
+          # jax` cell is satisfied and does not upgrade.
+          pip install "jax[CPU]==0.11.0"
       - name: Build Lectures (+ Execution Checks)
         shell: bash -l {0}
         run: jb build lectures --path-output=./ -W --keep-going

.github/workflows/execution-win.yml

@@ -35,7 +35,14 @@ jobs:
       - name: Install Jax [CPU]
         shell: bash -l {0}
         run: |
-          pip install "jax[CPU]"
+          # Pinned: jax 0.11.1 (2026-08-17) regresses XLA:CPU execution --
+          # numpy_vs_numba_vs_jax's lax.fori_loop and lax.scan cells go
+          # quadratic in n, so this -W build dies on CellTimeoutError. Matches
+          # the pin already in cache/ci/publish.yml; evidence and the exposure
+          # map are recorded in QuantEcon/workspace-lectures#49. With jax
+          # already present, the lecture's unpinned `!pip install quantecon
+          # jax` cell is satisfied and does not upgrade.
+          pip install "jax[CPU]==0.11.0"
       - name: Build Lectures (+ Execution Checks)
         shell: powershell
         run: jb build lectures --path-output=./ -W --keep-going