The brain-capture extension only went one way: browser -> vault. This adds
the return path — read the form on the current page, answer what the vault
supports, and leave the rest blank — and folds both directions into a single
two-tab extension renamed from "Brain Vault Capture" to "Brain".
Retrieval never calls a model. `obsidian-wiki context-pack --json` ranks the
vault deterministically and the model does one narrow job: map retrieved facts
onto fields. One `claude -p` / `codex exec` invocation per fill, billed to the
subscription the user already has. Nothing is ever submitted.
A native messaging host bridges the two, staged into ~/.obsidian-wiki/ rather
than run from the checkout. Chrome's children do not inherit your shell, and
all three consequences bite:
- macOS TCC: ~/Documents is mode 700 with an ACL, and a native host inherits
Chrome's TCC context, so a checkout there cannot be exec'd at all. Chrome
reports this as "Native host has exited", identical to a crash.
- PATH: Chrome passes a minimal PATH, hiding claude/codex in ~/.local/bin.
- USER/LOGNAME: Claude Code reads OAuth credentials from the macOS login
Keychain and needs these to find them, else "Not logged in" despite a valid
session.
The host bookends every run in its log so those failures stay distinguishable,
re-validates every returned fill against the real form schema (an injected
value cannot reach a field the page never advertised), and forwards the pack's
instruction_policy so vault excerpts stay data rather than instruction.
Form-schema extraction resolves labels via aria-labelledby before aria-label:
Google Forms puts aria-label="Your answer" on every paragraph field while the
real question sits behind aria-labelledby, so checking aria-label first
silently mislabelled exactly the textarea fields. Values are written through
the native setter with input/change dispatched, so React-controlled forms see
a genuine edit.
Docs: docs/browser-extension.md, linked from both READMEs and the docs index.
Also backfills the untranslated tagline from #159 into README_TW.md.
ar9av