PROP-049 — the snippet genre: no presupposed disciplines

1. The defect this repairs

01Agents creating fresh VibeVM projects created vibevm/vibespecs/WAL.xml unasked (owner observation, 2026-08-23). The machinery is clean — vibe init scaffolds no WAL, and both WAL checks return silently when the file is absent («a project convention, not part of the package manager's contract»). The cause is the PACKAGE chain: (a) redbook hard-pulls flow:wal, whose snippet speaks in unconditional imperatives («canonical… read before anything else»); (b) four UNRELATED snippets presuppose the WAL in passing — sync-from-code's «record in the WAL» imperative, health-audit's and git-atomic-commits' «the WAL» asides — so even without redbook the compiled STATIC of a small discipline set tells an agent a WAL exists. An obedient agent reads its static lane and mints the file. Not every external project wants a centralised WAL (a multi-developer team may run many WALs, or none); the presupposition takes that choice away.

2. The genre rule

02A boot snippet never presupposes another discipline. A snippet speaks unconditionally only about its OWN flow; any mention of another flow's artifacts or duties is CONDITIONAL — and the only lawful conditional form is structural, not verbal: the mention lives in a snippet fragment guarded by when = "installed:<group>/<name>", so the text physically enters a project's lanes only when that discipline is actually installed. Prose hedges («if you keep a WAL», «or equivalent») are NOT the lawful form — they are unverifiable by machine and still teach the concept unasked. This is ##THE-LAYER-LAW's sibling: a presupposition must never travel ahead of its own discipline.

3. The mechanism — the installed: predicate

03when grows a second predicate class: installed:<group>/<name>, resolved at INSTALL time. Unlike os:* (resolved by the reading session), installedness is known when the boot artifacts are generated: a fragment whose condition holds participates normally (static compilation included); one whose condition fails is OMITTED ENTIRELY — no STATIC bytes, no INDEX entry. Physical absence, not a softened sentence: the tokenomics-preferred form (PROP-048 — the inapplicable is never loaded).

04The manifest grows optional snippet fragments. [boot_snippet] stays the single main declaration (unchanged manifests keep parsing); an optional [[boot_snippet.fragment]] array adds {source, when} entries — each fragment a separate authored file, each with its own when (os:* or installed:*). Cross-discipline mentions move from the main snippet into fragments.

4. The gate — the concepts dictionary check

05A flow declares its concept tokens. The manifest's optional concepts = […] (under [boot_snippet]) names the tokens that mean this discipline — for flow:wal: "WAL", "vibevm/vibespecs/WAL.xml". The dictionary is assembled from the world (authored packages and installed manifests), never hard-coded into the checker.

06The check: a foreign concept in an unconditional snippet is an error. A vibe-check cell scans authored snippet sources: a token owned by package D, found word-bounded in the main snippet (or any fragment NOT guarded by installed:D) of package P≠D, is an ERROR naming the token, the owner and the repair («move the mention into a fragment guarded by installed:<D>, or drop it»). The dependency exemption: a declared [requires] on D guarantees co-installation, so P's bare mention of D's concepts is lawful (wal-specspaces presupposes the wal it hard-requires by construction). Code spans and fences are opaque to the scan, as to every markup scanner. Proven by a red fixture; a future publish wave runs the same cell as a C6 gate. Enforcement is three-point: the compiler (fragments are the only lawful conditional form), the panel/check (this cell), the publish gate. Softened 2026-08-23 (owner F7 ruling, PROP-050 ##CONCEPTS-GATE-SOFTENED): the cell speaks in WARNINGS, homonymy is lawful (an own concepts declaration owns the word), several owners dedup into one warning silenced by a lawful relation to any one of them; the ignore-concept-warnings subtree mute and the seeping-edges narrowing of the dependency exemption land with the visibility waves.

5. The repairs shipped with the wave

07The four presupposing snippets move their WAL mentions into installed:org.vibevm.world/wal fragments — sync-from-code (the flow line and the «record in the WAL» imperative), health-audit, git-atomic-commits, conflict-protocol (its «WAL or equivalent» hedge becomes a fragment too: the hedge form is exactly what §2 outlaws). The main snippets keep their own-discipline text, rephrased where the WAL was load-bearing.

08redbook stops hard-pulling flow:wal. The book still TEACHES the WAL method (its chapters are untouched); adopting the discipline is an explicit flow:org.vibevm.world/wal install — installation returns to meaning consent. The host adds its own direct flow:org.vibevm.world/wal entry (static-transitive, like its wal-specspaces neighbour), so the host's lanes keep the flow it genuinely runs. The catalog consequence: once unbundled, the book snippet's member lines about the wal family are presuppositions like any other — they move into installed:-guarded fragments, so the edition's catalog shows the members a project actually installed.

09The wal snippet names its own genre. One added clause: this flow is the single-developer, central-WAL convention; a multi-developer project chooses its own session-durability scheme — many WALs (see flow:wal-specspaces for the registered-subprojects form), or none — by not installing this flow or by superseding it.

6. Rollback

10The owner's escape hatch, named. Every change is package-local or additive: fragments fold back into main snippets, the redbook dependency line returns, the predicate and the check cell are removable without touching any consumer contract. Nothing here moves an anchor or a public wire format.

7. Companions

11PROP-035 (the link model whose dynamic + when this predicate extends), PROP-024 ([boot_snippet] manifest surface), PROP-048 (##THE-LAYER-LAW, ##MECH-DYNAMIC-CONDITIONS), the wal and wal-specspaces flows.