Cesarus85--mjolnir-vr/docs/object_matching_logs/libcmt_rand_obj.md

libs/libcmt/rand.obj exact-match ledger

This atomic lane starts from campaign commit 0276e8d6. The object was MISSING at config index 765, absent from config/parked.json, every Git ref, active worktree, and existing object log. January owns two functions and no runtime data in this object.

Plain-English behavior

srand stores a caller-supplied seed in the current thread's CRT state. rand advances that seed using Microsoft's traditional linear-congruential formula (seed * 214013 + 2531011) and returns bits 16 through 30. The seed is per-thread rather than global, which is why both functions first call _getptd.

Provenance and target inventory

The XDK 3911 libcmt.lib archive has SHA-256 60aa4c87c97eeb6662b31d9d37cf3caba1afabaec72c47b090e7a0ce8b632f55. Its obj\i386\rand.obj member has SHA-256 a2b22cace99476d94c04c5e54e16c8a3f6bfe38fb13bb9768e77451c07a7b9ef, compiler identifier 0x001c2426, ordinary C CodeView/line records, and source path d:\xbox-finalfre\private\sdktools\crt\crtw32\misc\rand.c. The member is itself strict-exact to January; this is primary Microsoft C provenance, not an inferred algorithm or vendor assembly.

Strict inventory:

• _srand: 13 bytes, one REL32 at +1 to __getptd + 0, normalized SHA-256 28489ecb8d8373d25b62e9749486e9768f107c1d0b70ce44fe8c7f9d18c8aec4;
• _rand: 34 bytes, one REL32 at +1 to __getptd + 0, normalized SHA-256 82a11d96726827a0e4767b31c0a21b4c70036f25b7ca010b9e8edcf1f25430fd;
• both are external, pick-no-duplicates .text COMDATs with exact symbol storage/type/value; no aliases and no owned .rdata, .data, or .bss.

The readable thread_data prefix is reused from the already admitted strtok.obj: named fields through random_seed naturally place the seed at January's proven +0x14. No padding blob, raw offset access, or fabricated layout is needed.

Experiment matrix

ID	Source shape	Size T/B	Relocs T/B	Strict result	Decision
E01	Typed thread-data prefix; direct seed assignment; named LCG constants and one stored update	13/13, 34/34	1/1, 1/1	both functions and ownership exact	accepted first compile

Any later experiment must vary one evidence-backed source factor, record its strict measurements here, and be reverted unless it improves the complete object result.

Strict verification

XDK 3911 CL 13.00.9254.1 compiled the accepted source with the unchanged libcmt /O1 /Gy /I"xbox/include" flags. Hardened comparison reports section_infos_equal for both functions, including size, normalized bytes, relocation address/type/destination/addend, COMDAT selection, linkage, and ownership. Candidate .drectve and CodeView sections are discardable build metadata, not January runtime ownership.

The full halobetacache_build and libcmt_build pass. Regenerated progress reports 329/833 objects overall, 267/468 Halo objects, and 62/212 libcmt objects. Libcmt has 84/476 exact functions and 4,217/55,015 exact code bytes. This object contributes one object, two functions, and 47 bytes. The semantic audit reports zero unit errors.

The clean-commit fail-closed per-unit snapshot/check was followed by deletion of the generated object and a forced rebuild. _srand and _rand both remain still_exact, with no failures, warnings, changed non-exact siblings, newly exact surprises, or ownership changes. The complete tooling suite passes 179/179 tests.

House/Berth and original-bug audit

The source uses explicit types, named constants, named parameters, ordinary C control flow, and the proven thread-state structure. It contains no assembly, volatile, forced inlining, undefined behavior, type-punning, opaque cast, packing/alignment trick, flag change, byte patch, or comparator waiver. Both functions have a single natural return. The unsigned wraparound in the seed update is defined C behavior and is required by the algorithm; no original bug or defensive fix is implicated.