* Rewrite comments in Google developer documentation style
Rewrite the comments and docstrings across the backend core modules so they
read plainly. The previous prose was accurate but dense and figurative, which
made it slow to skim.
Applies the Google developer documentation style guide: short sentences, active
voice, present tense, American spelling, and no metaphors, idioms, or
rhetorical asides. Replaces em-dash chains with separate sentences.
Phase 14 SP1. The tree goes into the schema and nothing reads it yet: a
`branches` table, `branch_id`/`depth` on actions and memories, a head pointer
on adventures, migrations 46-52, and a server-side backfill that re-reads every
existing adventure as a tree with one branch. `depth` holds the number `index`
already held, gaps included, so no story changes — a linear story *is* a tree
with one branch, which is what makes the SP0 baseline passing unmodified the
pass condition rather than a hope.
The writer had to come with it. No migration will ever visit a row written
after it ran, so columns backfilled today and populated next subphase would
leave a hole exactly the width of one deploy, and from SP2 on a row without a
branch is a row no read can see. `app/tree.py` owns that: one module, because a
node written without a branch fails by disappearing rather than by raising.
Three things the schema itself insisted on:
- `adventures.head_branch_id` is a plain integer, not a foreign key. Pointing
both ways makes the two tables a cycle create_all cannot order, and its
escape hatch needs an ALTER SQLite does not have. It is a cache, and a head
naming a branch that is gone recovers onto the root.
- `lineage` is NOT NULL, so the backfill inserts `'[]'` and fills it in a
second pass guarded on `json_array_length(lineage) = 0` — not `= '[]'`,
because Postgres `json` has no equality operator.
- SQLite will not drop a column a foreign key names, which is how two existing
tests broke: they simulated an old database by rewinding the stamp while
leaving the new columns in place. Every ADD COLUMN migration is now
idempotent, and `tests/test_tree_migration.py` builds a genuine schema 45 by
rebuilding three tables from frozen DDL so the real ALTERs run.
297 tests green, 14 of them new. `branches` costs 0.1 kB of a 733.5 kB turn;
page load and index are byte-identical to the recorded figures.
The deploy that ships this needs one `VACUUM FULL actions;` on the direct
endpoint afterwards — it rewrites every row.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017Dvvqn9ZDR4ixeFPHNbww7
Parth