AnachronautandClaude Opus 5 bb065fe221 Tab finishes a word somebody started ...

The first word of a line, against the shell's fifteen commands. One match goes in
with a space after it, because a word that can only be one thing is finished.
Several are folded into their longest common prefix and that goes in, which is
the most that can be said without guessing which was meant - and if that adds
nothing, the matches are listed and the line put back underneath.

THE LINE COMING BACK IS THE HALF I EXPECTED TO BE HARD and it was already
solved. The prompt has been reprinted somewhere else entirely, so the editor's
idea of where the line begins is wrong - but editAnchor works that out backwards
from where printing ended, precisely so it survives the screen moving. Listing is
a redraw it already knew how to do.

editInsert became editPut, a routine, because completing a word puts in several
characters and every one of them is that. Which cost a bug immediately: the old
inline code left the insertion point in A, and a RET puts A back to what the
caller had.

Two more bugs worth naming, both mine and both the same shape - a pointer that
had moved:

THE CANDIDATE'S START HAS TO BE KEPT. The comparison walks DP3 through the name
as it matches, so by the time a match is declared, DP3 points at the part AFTER
what was typed - and that is what got copied. "he" completed to "he" because the
answer taken was "lp".

AND THE INSERTION STOPS AT OR PAST, not exactly equal. With the wrong answer the
two counters passed each other and the loop ran off the end of the buffer,
filling the line with whatever was next in memory. They cannot pass each other
now, and the branch stays, because the cheaper failure is worth nothing.

MY OWN TEST HAD A HOLE and breaking the code found it. The later-word case
pressed Tab after a space, where there is nothing to finish anyway, so it passed
whether or not the shell checked which word it was on. It types "echo he" now,
which would become "echo help" if it did not.

The assembler's label table went past 1024 and is doubled. A ceiling reached
once will be reached again, and it is pointers into source already in memory.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW

2026-09-01 17:43:48 -04:00

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