schema_version enforcement reaches only 4 of ~18 command modules

[db-tycoon-stephen]

Found during review of #178 (T2-4). Filing for scoping rather than as a defect — the current behaviour is the right trade, but the coverage is narrower than "enforcement layer" implies.

Current state

The stale-version warning and the future-version gate both live in load_config(). Only four modules call it:

src/tycoon/commands/sources.py
src/tycoon/commands/sync_cmd.py
src/tycoon/commands/explore.py
src/tycoon/commands/run_all.py

Everything else still uses the import-time singleton config = TycoonConfig() — doctor, db, transform, history, observability, status, start, register, semantics, profiles, fivetran, notify, schedule, setup.

Verified behaviour

Against a project with schema_version: 99 (unsupported):

command	result
data sources list	gated, exits 1
doctor	runs to completion, rc=0, no mention
db info	runs, no mention
transform build	runs, no mention

And on a stale project (no schema_version), only data sources list nudges; doctor / db / transform / history / observability are all silent.

So the same project produces a hard exit from one command and normal operation from the next. doctor — the command most likely to be run when something looks wrong — is the one that says nothing.

Options

1. Hoist the check into the Typer root callback in cli.py. Runs once per invocation, covers every command, and init --upgrade stays reachable because it doesn't route through load_config. Small and uniform.
2. Accept it as staged and let coverage arrive with the rest of the singleton removal. T2-3: Replace config singleton in ingestion commands with load_project() injection #94 covers the ingestion commands only, so the remainder needs its own ticket either way.

Recommend (1) if enforcement is meant to be real before v0.1.11 ships; (2) is defensible if the singleton removal is close. This is a scoping call.

Related

• T2-3: Replace config singleton in ingestion commands with load_project() injection #94 — T2-3, singleton replacement in ingestion commands (partial by design)
• T2-4: tycoon.yml version field enforcement #96 — T2-4, the enforcement layer
• [Milestone 2] tycoon.yml schema + config singleton replacement #83 — M2 milestone

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Mirrored in Jira: PTC-114 (Subtask of PTC-84, [Rewrite M2]). Dev work continues here.