ci: raise the conditional-compilation cap so checkout stops killing the job

[FenrysUnchained]

One functional line: timeout-minutes: 5 → 20 on the conditional-compilation job. The rest of the diff is the comment explaining why.

The failure

That job was cancelled mid-checkout three times on 2026-08-26, across two unrelated branches — #808 once, claude/arcade-launch-screen-revamp-driys twice. Every check step showed skipped, so the checker never ran a line, and it surfaced as a red X that said nothing about the code:

Checkout                          17:34:33 → 17:39:33   (5m00s)  cancelled
Verify the checker still detects                        (0s)     skipped
Check conditional compilation                           (0s)     skipped
Check prism shader wiring                               (0s)     skipped

Why 5 was the wrong number

The cap was sized for the checks, which take seconds. In practice it bounds the checkout, which the job does not control:

What the job downloads	~1.4 GB of Assets/
What it actually reads	~5 MB — 608 KB of .cs, 4.7 MB of .shadergraph / .shader / .hlsl

.gitattributes carries only two filter=lfs rules, so nearly all binary assets live in ordinary git and fetch-depth: 1 still pulls the lot. Healthy runs finish in 57–90 s; when throughput dips they don't, and at 5 minutes the job gets killed before it starts working.

Raising the ceiling does not make the job slower — it only stops a slow clone being reported as a failing check. At 20 minutes, a run that genuinely reaches the cap is a real fault worth failing on.

What this deliberately does not do

The narrower fix is to stop fetching what the job never reads: filter: blob:none plus a sparse-checkout of *.cs / *.shadergraph / *.shader / *.hlsl / Tools. Left for its own change, because it needs a validation pass rather than a guess.

Verified in passing that it would at least fail safely: with a shader file absent, the wiring checks raise FileNotFoundError rather than passing, so a wrong sparse pattern breaks CI visibly instead of going green on an unchecked tree. Worth knowing before anyone attempts it.

The root cause beneath both is that the binary assets are not in LFS, which slows every job in this repo including the Unity build. That's a project-wide migration, not this PR.

Verification

• Workflow still parses; all three jobs (resolve, conditional-compilation, unity) load
• conditional-compilation's step list is unchanged
• unity's own timeout-minutes: 240 untouched — the 5 was a deliberate per-job choice, not a default, so this raises it rather than removing it
• Functional diff is exactly - timeout-minutes: 5 / + timeout-minutes: 20

This PR's own CI run is the test: it exercises the changed job.

🤖 Generated with Claude Code

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Generated by Claude Code