Tracking: MDL beta — canonical syntax, language versioning, data-first editing

[ako]

Tracking issue for the MDL alpha → beta work. Releases are weekly. Every change of meaning is tied to the mdl 1; header, so no change needs a warning release: beta is a single release, cut when mdl 1 is complete (target: about four weeks, around 2026-10-24). Until then, mdl 1 is a preview and is not emitted by describe/fmt.

• Proposal: PROPOSAL_mdl_beta_syntax_freeze.md. §9 holds the implementation plan and the week-by-week schedule.
• Decisions: ADR-0010 (canonical syntax rules R1–R12), ADR-0011 (language versioning), ADR-0012 (MDL-first and data-first editing). All are in PR docs: MDL beta syntax proposal and ADR-0010..0012 #702.

Step 1

Foundations:

• Round-trip harness: describe → exec on a Studio Pro fixture must write nothing (commit PedApp) #703 Round-trip harness and PedApp fixture (0.1, 0.2)
• Deprecation registry for MDL aliases (MDL-DEPRnnn), generalising MDL065 #709 Deprecation registry (1.2)
• MDL language header 'mdl <n>;' with version-gated semantics (headerless = mdl 0) #710 mdl <n>; language header (1.5)
• Skills: choose the edit mode by document owner; steer agents to alter for Studio Pro documents #711 Skill guidance: choose the edit mode by document owner (0.6)

Bugs:

• Association storage flips Table→Column when describe output is re-run; diff reports no change #704 Association storage flips Table→Column on round trip (0.4)
• Re-running describe output loses page translations, nanoflow annotations/export level, Java action export level, snippet Type #705 Round-trip losses: pages, nanoflows, Java actions, snippets (0.4)
• Silent drops: throw, float/currency/date types, parenthesised association options, enum-value docs and index names #706 Silent drops: throw, float/currency/date, association options (0.3)
• describe output that does not re-parse or loses data; configuration describe leaks DatabasePassword #707 describe output that does not re-parse; configuration password leak (0.3)
• Read commands give wrong answers: impact misses attribute usage, describe fragment always fails, structure hides microflow counts, --json not pure #708 Read commands that give wrong answers (0.5)

Parallel track (beta gate):

• Generic alter <type> X { set / insert / replace / drop } with per-doctype target resolvers #712 Generic alter with target resolvers (4.1)
• alter microflow: content-addressed target resolver (output variable, caption, statement pattern) #713 alter microflow target resolver (4.2a)

Step 2

The mdl 1 semantics, behind the preview header (2.1, 2.4, 2.5), together with fmt --upgrade (1.3), the graph splice and placement (4.2b, 4.2c).

Step 3

Canonical describe (2.6); Phase 3 canonical forms added to the grammar; conformance gate (1.4); insert/replace/drop and diff-then-patch create or modify for microflows (4.2e, 4.2g).

Beta

mdl 1 is frozen, documented, and emitted by describe/fmt. The 4.2 acceptance test on VAL_Feedback must pass. If it does not, slip beta: that no longer costs compatibility.

Issues for steps 2–3 are filed when step 1 is done.