Optional code-intelligence provider contract (GBrain / Sourcebot / Graphify)

[time-attack]

Optional code-intelligence provider contract

Adds a small, optional way to pick how your codebase gets indexed and
searched, so gstack stops maintaining a home-grown indexer and instead defines a
contract that external providers implement. gstack stays fully functional with
nothing selected — callers fall back to grep / the file-only decision store.

What you can do

gstack-code-intelligence options              # GBrain (recommended), Sourcebot, Graphify + live availability
gstack-code-intelligence select graphify
gstack-code-intelligence consent               # per-repo; only for providers that send code off-machine
gstack-code-intelligence index                 # index this repo with the selected provider
gstack-code-intelligence search "what calls db"

The contract

Repo-oriented, not document-store: register_source / refresh / search /
status are required; add / delete / export are optional capabilities a
provider may advertise. Typed failures; a closed capability set enforced at
construction. Consent is two-axis and explicit: per-repo egress consent before
any content leaves the machine (skipped for local providers), and install consent
for Graphify (never auto-installed).

Three real, runtime-driven adapters (no MCP client)

• GBrain (recommended) — gbrain CLI; full contract fit incl. the document ops.
• Sourcebot — self-hosted server over HTTP (POST /api/search + a
  config.json edit). Local tool; no API key needed with anonymous access.
• Graphify — local graphify CLI (graphify update + graphify query);
  fully local, never auto-installed.

Verified against real environments

Every adapter was driven against the real running tool in an isolated environment,
not just unit fakes: real Postgres-backed GBrain 0.42.56, live Sourcebot
v6.5.0 (keyless via anonymous access), and real Graphify 0.9.23 — all three
index + search a real repo end-to-end. Two of the first-round fixes were wrong and
real execution reversed them (a gbrain flag removal that broke code indexing, and
a graphify LLM claim); both are corrected and recorded honestly in
docs/designs/CODE_INTELLIGENCE_PROVIDER_CONTRACT.md. 24 unit tests, pinned to the
real captured output formats, no live tools required.

Scope / not in this PR

Standalone library + CLI + design doc; no skill-template, runtime-config, or
generated-file changes (so no gen:gstack2 / parity re-baseline). Routing the
existing gstack-decision-semantic / brain-context-load consumers through the
contract, and retiring the bespoke GBrain glue, are the documented phase 2–4
rollout — the old glue is untouched here.

🤖 Generated with Claude Code

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Summary by cubic

Adds an optional code‑intelligence provider contract and CLI so repos can index and search code via GBrain, Sourcebot, or Graphify. Keeps existing flows working with zero setup and falls back to grep when no provider is selected.

• New Features

  • Provider contract: repo‑oriented. Required ops: register_source, refresh, search, status. Optional: add, delete, export. Typed failures and capability gating.
  • Adapters: GBrain via gbrain CLI; Sourcebot over HTTP (POST /api/search); Graphify via graphify CLI. Live availability checks with graceful PROVIDER_UNAVAILABLE degrade.
  • Consent: explicit per‑repo egress consent for non‑local providers. Graphify is fully local and never auto‑installed.
  • CLI: gstack-code-intelligence options|status|select|consent|index|search.
  • Verified: real runs against GBrain 0.42.56, Sourcebot v6.5.0 (anonymous local), Graphify 0.9.23. 24 unit tests pinned to real output formats.
  • Backward‑compat: no changes to current consumers; old glue remains. Fallback uses grep and the file‑only decision store.

• Migration

  • No action required. gstack works unchanged without a provider.
  • To opt in: run gstack-code-intelligence select <gbrain|sourcebot|graphify>, then consent (for non‑local), index, and search "<query>".

^{Written for commit ab7989c. Summary will update on new commits.}

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