WP-005: Engine-family check across Case File ISOs

Status: 📝 Drafted Phase: 1 — Format Research Depends on: — Companion EC: EC-003 Estimated effort: Half-day

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Goal

Determine whether Case File #1 and Case File #2 use the same engine as the TerraGlyph trio (Showdown / Phantom / Jinx). Specifically: do their discs contain TGIFILE.ART, Scooby.exe, object.ini with compatible structure? Satisfies Phase 1 exit criterion #4 and locks Phase 5 scope per the vision’s “Scope rule.”

Background

TerraGlyph Interactive Studios shut down in 2001 (Wikipedia-confirmed). The Case File titles (#1 = 2002, #2 = 2003) shipped after that closure under a different developer. The vision currently treats the Case Files as “conditional” — included if engine-compatible, excluded if not.

This WP is the empirical answer. The findings shape:

• Phase 5 scope rule (minimum / extended / conditional)
• 02-SCUMMVM-INTEGRATION.md §3 detection table (one engine entry vs. two)
• Whether the eventual ScummVM PR claims 3 titles or 5

Scope

In scope:

• Mount each Case File ISO read-only
• Generate a file listing (name + size) per disc
• Diff against Showdown’s file listing
• For files that exist in both: hex-inspect the first 64 bytes of TGIFILE.ART, Scooby.exe, object.ini to check for matching structure
• Write a binary go/no-go per Case File ISO
• Record findings into docs/formats/tgifile-art.md Findings → “Cross-title verification” and docs/01-VISION.md Phase 5 scope rule

Out of scope:

• Decoding any payload in Case File TGIFILE.ART (out of WP-002 scope until base case works on Showdown)
• Phantom and Jinx verification — those are TerraGlyph titles and assumed compatible until proven otherwise; spot-check is optional
• Activity Challenge or Case File #3 verification — both already flagged as out of scope, no work needed

Dependencies

• Disc mounting (Windows native, WinCDEmu, or equivalent)
• Hex viewer
• Disc-mounted Showdown for diff reference

Exit criteria

1. File listing produced for Case File #1 and Case File #2 discs.
2. Diff against Showdown’s listing produced and recorded in docs/01-VISION.md or a sibling note.
3. For each of Case File #1 and #2, a binary verdict: COMPATIBLE (shares engine with TerraGlyph trio), INCOMPATIBLE (different engine, treat as out of scope), or INDETERMINATE (file names match but headers don’t — needs deeper inspection).
4. docs/formats/tgifile-art.md Cross-title verification section populated with what the first 64 bytes of each Case File TGIFILE.ART look like vs. Showdown’s.
5. Vision doc Phase 5 scope rule confirmed or updated based on the verdict.

Deliverables

• File listing diffs at docs/findings/case-file-disc-diff.md (new file, brief)
• Updated docs/formats/tgifile-art.md — cross-title section
• Possible update to docs/01-VISION.md Phase 5 scope rule

Notes

• Parallel-safe with WP-001 through WP-004.
• This is a small WP but the answer it produces is load-bearing — it determines whether the ScummVM engine ships covering 3 titles or 5. Worth doing early so subsequent work is correctly scoped.
• If the answer is “INDETERMINATE,” recommend re-running after WP-001 closes (Ghidra may reveal whether the same loader code is present in Scooby.exe across versions, even if archive bytes differ at the surface).
• The hypothesis from the vision is that the post-TerraGlyph studio inherited the engine via IP transfer through the TLC → Riverdeep acquisition. If true, the file structures will match. If false, the Case Files were rebuilt on a different engine and the structures will diverge clearly.