[Tommyapi]

read_until(b"aab") misses the delimiter in b"aaab": after the third a, the current fallback keeps progress 1 instead of 2. This change retains the longest matching prefix suffix, so the following b completes the match. It also fixes b"abac" in b"ababac".

Related: #1. Submitted as a draft for review and import into the internal tree, following CONTRIBUTING.md.

The generator considers fallback lengths in descending order, emits only the longest state for each next-byte value, and skips the byte already handled by the normal match branch. This avoids the bytecode expansion found in an earlier unsubmitted candidate. Whole-delimiter overlap rejection and the timeout/max paths remain unchanged; generated drivers are untouched.

Validation against released base 8fd8135e8781aeacbbb7939b94f09cec96e44386:

• Linux Python 3.12: pip install -e '.[cyphal]' and nxs --version passed (nxs 1.1.0) in an isolated environment.
• Offline actual code generation plus a bounded interpreter of the public opcode subset: 6 explicit fixtures and 3,570 short delimiter/input combinations passed. The released source failed 128 of those combinations against bytes.find.
• 12 delimiter shapes of 32/64/96/128 bytes compiled through the emitter; 36 associated behavior cases passed. For the tested 64-byte repeated/mixed/unique shapes, sizes are 2,641 / 3,061 / 3,881 bytes, versus 3,881 for each released program. No previously in-budget tested shape crossed 4,096 bytes.
• Tested one-byte, a5 5a, and CRLF programs remain byte-identical. Existing invalid-delimiter rejection was preserved.

The private VM tests, hardware, asynchronous byte arrival, and full driver deployment were not tested. Some 96/128-byte programs exceed 4,096 bytes in both versions; successful emitter construction is not a deployment claim. Please port the small fixtures to the internal regression suite and review the full program budget before accepting.

Prepared for ERDI TECH LTD with AI-assisted source analysis, implementation, and independent review. No ERDI hardware integration or commercial compatibility is claimed.