A join can collect the files its branches produced

[gedaiu]

Why

#35 let a join collect what its branches produced, but only values. An agent branch hands back a file far more easily than a value, which has to ride inside its one-line result marker as JSON inside a string. Lore's section pods are agents, so the join could not collect what they write.

What Changed

• A collect need now reads a branch's file output from the blob store when the join opens, and puts its text (UTF-8) in the JSON array, in branch order. A value still goes in as it is. The kind of each output comes from the station the branch ran, by its hash.
• Line validation accepts a collected name that a fan-out body produces as a file as well as a value (it still refuses a name no body produces, or one that more than one body produces).
• docs/entities/assembly-line.md and the fan-out entry in docs/decisions.md say files are collected.

Alternatives Considered

• Making the agent put its patch in the result marker as a JSON string: nested escaping is the kind of thing a model gets wrong, and the marker is a single line.
• Having branches push files to the spec branch: concurrent pushes race at the ref and need a rebase loop in every prompt.
• Collecting blob hashes and leaving the join to fetch them: the join is a service station and would need blob access through the API for what the floor already holds.

ADRs & Architecture

Amends the "Fan-out and join" decision in docs/decisions.md. A file larger than the blob cap cannot exist, but a collected array of large files makes a large need; nothing caps its length yet, as before.

Testing

Test-first: a store scenario where two branches produce files and report in reverse order, and the join opens with their text in branch order (421 store tests pass against Postgres); the validation test now expects the plain wording. Typecheck and lint are clean. Not exercised on a cluster.

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🤖 Generated with Claude Code

[lore-agent]

Lore is reviewing this PR — 9f9e087e-832f-42ef-9714-900ea53ba087.

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[lore-agent]

Lore review — Approved

Correct implementation of file collection in fan-out joins; one nit on N identical DB calls per branch

Must fix (0) · Consider (0) · Nits (1)

Reviewed by claude-sonnet-4-6

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Posted by floor, visit 1e766e07-72c9-406c-bcda-d9c0cd929dea.