Walkthrough adoption path cannot succeed: 'assent run' refuses the shipped starter packs #158

Severity: High — every adopter following the front door. Review finding D1 (consolidated XREV review); deferred whole by #157 (openspec/changes/p5-xrev-final-remediation/proposal.md Non-goals). Re-verified at 1c4e71e.

docs/usage/walkthrough.md:49 has adopters cp -R assent/examples/packs/topic-registry/.assent .assent. The CI job at :237 runs assent run --project … --mr … --subject … --bot-author … and promises (:254-256) "approval, and merges. Nobody was interrupted." On the shipped packs that path cannot succeed:

1. Default filenames missing. assent run defaults to --policy .assent/merge-policy.yaml and --binding .assent/ruleset-binding.yaml (cmd/assent/run.go:132-133). Each of the three packs ships only bindings.yaml and config.yaml at .assent/ top level (find examples/packs/*/.assent -maxdepth 1 -type f). The walkthrough passes neither flag, so the first run dies on the policy read.
2. Packs are test-shaped, not run-shaped. Each rule file is a standalone one-rule kind: MergePolicy document, the catalogue layout assent test loads with catalogue.LoadFromDir. --policy loads one MergePolicy document (policy.LoadMergePolicy), so pointing it at any single rule file leaves the binding's other require[] obligations uncovered → REVIEW.
3. Multi-binding refusal. Every pack's bindings.yaml declares 2 bindings (dev and prod). selectBinding (cmd/assent/run.go:504-512) hard-errors when len > 1: "(class, environment) routing needs the Config class-matcher (not wired in this lane)". assent test hides this because selectBindingForTest collapses the pair to the strictest binding.
4. No --config in the recipe. Facts resolve only from --config (run.go:135, now documented that way). The walkthrough CI block still omits it, and resolveRunFacts returns empty facts when conf == nil (cmd/assent/provider_host.go). The packs' ownership rule binds facts.author.groups → REVIEW.
5. No collection-entry reconstruction on run (found by Implement the final consolidated review remediation (D2,D3,D4,D5,D16,D17,D18; D1 deferred) #157's review). changeSetForGoverned uses document-mode change.Diff, and evaldecode.BuildEvaluationInput leaves EvalChange.Entry nil. Every entry.* predicate therefore binds the scalar fallback, so entry.owner in … → predicate.error → REVIEW, whatever the filenames are.

CI cannot see it: hack/dogfood-examples.sh runs only assent test / test --coverage. No gate drives assent run against a shipped pack.

Fix (spec-first lane, per #157's proposal):

• (a) DEM-S00 (class, environment) routing per D-142;
• (b) collection-entry reconstruction on the run path (E1-S05/E1-S08);
• (c) make the packs run-consumable, or teach run the catalogue layout;
• (d) add --config and the needed flags to the walkthrough CI block;
• (e) add a check: dogfood gate that drives assent run against the shipped packs through the existing fake forge (cmd/assent/run_*_test.go pattern);
• (f) record the filename, format and recipe gaps against D-142.

Until then, consider marking the walkthrough's Step 5/6 promise as not yet achievable on the shipped packs.