Retrospective: Six Days, Thirty-Four Versions

Every version tag from 0.1.0 to 0.33.0 was created between September 12 and September 18, 2026 — six calendar days for thirty-three tagged versions (0.13.0 skipped). Version 0.34.0 followed on the same day as a documentation-only milestone: the launch of this journal. That pace is only sustainable because of habits that were established early and never abandoned:

What held up across the whole project

• One capability per version. Nearly every version in this journal adds exactly one instruction, one directive, or one hardening fix — rarely more. That granularity is what makes a 6-day, 34-version history legible at all instead of a blur.
• A permanent regression test before moving on. From the very first lexer commits through COFF object output, no capability shipped without a test that stayed in the suite. tests/encode_file.cmake’s “assemble, then diff hex and/or decoded listing” pattern, established around 0.1.0–0.3.0, is still how most instruction-level features are checked today.
• Two toolchains in CI from day one. Windows/MSVC and WSL2/GCC both building and testing every milestone caught real bugs — a missing <string.h> include at 0.26.0, and a NUL-unsafe test at 0.25.0/0.25.1 — that a single-toolchain project would likely have shipped.
• A layout pass, introduced early (0.8.0), that every forward-reference feature since has depended on — jumps, relocation, TIMES/FILL counts, $/$$ expressions, and label-valued data all lean on the same offset assignment pass rather than reinventing it.
• Explicit rejection over silent misbehavior. --bits mode rejection (0.22.0), the [bx]-only memory operand (0.27.0), rejecting jmp abs in COFF output (0.33.0) — the project consistently chose to say “not supported yet” clearly rather than let an unsupported case fall through to incorrect output.

What’s still explicitly future work

As of 0.33.0, the README and this journal agree on what hasn’t been built yet:

• General 16-bit addressing modes beyond [bx].
• A defined boot-sector entry convention (segment state, stack, BIOS services) — the 0.28.0 fixture is byte-correct but not yet bootable.
• Source-level extern declarations and multiple data sections for COFF objects.
• Converting jmp abs into a linker relocation for object output.
• Full unsigned 32-bit/64-bit expression values for dd/dq (the storage width already exceeds what the expression evaluator currently allows).
• Consistent cleanup of parser.nodes, program.statements, and encoded byte buffers on error paths (a short-lived concern for a CLI process, but worth fixing before Kasm is used as anything but a one-shot tool).

Why this book exists

None of the above is a criticism — it’s the normal shape of an assembler built version-by-version with test-gated milestones. This journal exists so that shape stays visible: the order features arrived in, the constraints that shaped each one, and the handful of fix-up versions (0.18.1, 0.24.1, 0.25.1) that are just as instructive as the feature versions around them.

Future entries in this journal should keep the same discipline: one chapter per meaningful version or tightly related group of versions, written close to when the work happens, sourced from the actual commits and tests rather than from memory after the fact.