Bitcoin's Earliest Source Codebases: A Hash-Matched, Reproducible Differential Study of the November 2008 Preview, the SNI-Labelled v0.1.0 Archive, and v0.1.3

The earliest available Bitcoin release archive in the Satoshi Nakamoto Institute (SNI) corpus—which SNI labels v0.1.0—contains the serialized-protocol, consensus, and scripting features conventionally associated with its initial protocol, whereas an earlier preserved source preview differs materially and structurally. We compare hash-matched archives of the 15 November 2008 preview, the SNI-labelled v0.1.0 (SNI date 9 January 2009; internally VERSION=101), and v0.1.3 (SNI-dated 13 January 2009(?)) with a disclosed automated census followed by manual validation at source definitions, construction sites, and control flow; positive claims carry a file:line witness and absence claims a declared zero-count predicate. Between the preview and the SNI-labelled v0.1.0 archive, object-level version members are introduced into the block and transaction hash preimages (the preview's block and transaction objects carry no such member); nSequence moves from outputs to inputs, and finality changes from a wall-clock/output-sequence rule to a height/input-sequence rule; the proof-of-work nBits changes from a shift-count to a compact target and the retarget from a ±1 step to a proportional, boundary-triggered, clamped rescale; the coinbase reward rule changes from exact-equality to a maximum cap; and a general Script evaluator, P2PKH construction, Base58 addresses, and coinbase-maturity enforcement appear. The examined features are unchanged in v0.1.3. These results bound each observed transition—and each first-observed presence of a preview-absent feature—by artifact ordering: the feature is absent from the November preview and present in the SNI-labelled v0.1.0/101 archive. Because SNI assigns the later archive a date of 9 January 2009, after the 3 January genesis block, while its exact build or circulation date remains uncertain, the source comparison alone does not establish that the transition occurred by genesis. The on-chain genesis block independently attests a serialized subset (its coinbase output value, its bare-P2PK-without-OP_CODESEPARATOR script, its version-1 header, and its nBits bytes), while the denomination convention and the general subsidy rule are not block-encoded. The contribution is the uniform three-artifact census, declared provenance, and artifact-order-bounded comparison across the three earliest available codebases in the SNI corpus. This record contains the manuscript (PDF) and the reproducible replication package (bitcoin-earliest-codebases-artifact-v1.0.0.zip, SHA-256 7f146ab48829780a5a027df035674fcc1cec407248294422f76d675067922e34). Running "python tools/run_all.py --full" reproduces every computational claim from the hash-verified primary source. License: CC BY 4.0 applies to the original contributions only (manuscript, tools, documentation, evidence). The corpus/ directory redistributes historical Bitcoin materials from the Satoshi Nakamoto Institute (archive containers, extracted source, and any embedded executables/resources); these retain their original license terms.