mimic-big/tasks/spec-decisions.md

# Spec decisions log

This file tracks implementation arbitrations *on top* of the frozen spec
(`Projects/Mimic — Spec.md` in the RT-SecondBrain vault).

Format: one entry per decision, newest first.

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## 2026-05-21 — Team kickoff decisions

### D-001 — SOC collaboration hypothesis
**Context.** Devils-advocate flagged the sociological assumption that SOC analysts
will cote in the live cockpit.
**Decision.** Hypothesis accepted as-is. No paper PoC. Risk owned by lead RT.

### D-002 — Mimic deployment location
**Context.** Spec §6 NF-network did not pin where Mimic is physically deployed.
**Decision.** Mimic runs on RT infrastructure. SOC client connects through the
existing RT reverse proxy (Caddy, out of Mimic scope). Mimic → Mythic / Home C2
through outbound VPN. RT R&D (TTP library, stealthy variants) never sits on
client premises.

### D-003 — Authentication strategy
**Context.** Spec mentions OIDC Keycloak but lab onboarding cost is high.
**Decision.** v1 ships **local auth** (username/password, bcrypt, Flask server-side
sessions). v2 adds Keycloak OIDC. The RBAC model is **group-based from day one**,
so OIDC will map claims to existing groups without touching application code.
SOC sessions remain a distinct mechanism (`soc_session.token_opaque` bcrypt hash,
clear token out-of-band).

### D-004 — C2 credential storage (T2)
**Context.** Engagement.config_json (encrypted JSON column) vs dedicated table.
**Decision.** Dedicated table `c2_credential (id, engagement_id, c2_type,
config_json_fernet, version, created_at, retired_at)`. Active row per engagement =
`retired_at IS NULL`, highest version. Rotation = insert + retire previous.
Fernet key in env, never in DB.

### D-005 — Cleanup template variable sources (T3)
**Context.** Jinja `{{outputs.X}}` source ambiguity.
**Decision.** Two accessors:
- `{{outputs.text}}` → `run_step.output_text` (stdout/UTF-8 text).
- `{{outputs.blob("<key>")}}` → reads from `output_blob_ref`, hard cap **10 MB**
  (consistent with F8 evidence limit), UTF-8 decoding with latin-1 fallback,
  silent refusal + log entry if the blob is non-decodable.
`regex_extract` always operates on the resulting string.

### D-006 — SOC session token storage (T4)
**Context.** `soc_session.token_opaque` storage form.
**Decision.** bcrypt hash. Clear token generated server-side at session creation,
returned **once** in the API response, delivered out-of-band to the SOC analyst.
Never re-displayable.

### D-007 — Reverse proxy scope
**Context.** Mimic exposure to internet for SOC client access.
**Decision.** Reverse proxy (Caddy + TLS + IP allowlist) handled by existing RT
infrastructure. Mimic ships an HTTP listener on localhost only; the deployment
playbook wires it behind the existing proxy.

### D-008 — Group-based RBAC vs spec F11 fixed roles
**Context.** Spec F11 declares 3 fixed roles (`rt_operator`, `rt_lead`,
`soc_analyst`) with an explicit permission matrix. Sprint 0 plan (B0.6, D-003)
introduces `group` / `permission` / `group_permission` / `user_group` tables to
prepare OIDC v2 claim-to-group mapping without code change.
**Decision.** Group-based model accepted as an implementation *layout*, **not** a
scope extension:
- The 3 spec roles MUST exist as the 3 seeded groups at bootstrap
  (`rt_operator`, `rt_lead`, `soc_analyst`).
- The F11 permission matrix is the canonical source: groups receive exactly the
  permissions of their matching role; no custom permissions UI v1.
- Custom groups, group editing UI, or per-engagement group overrides = OUT of v1.
- Any drift between seeded group permissions and the F11 matrix is a spec
  violation, not a configuration choice.

### D-009 — `ttp_version` table forbidden (H32 reaffirmed)
**Context.** Sprint 0 plan (B0.2) lists `ttp_version` among the initial tables.
Spec hypothesis **H32** explicitly excludes this: *"Snapshot de rejouabilité =
`run.snapshot_json` uniquement (pas de table `ttp_version` séparée —
simplification MVP)"*.
**Decision.** Drop `ttp_version` from the initial migration. The `ttp.version`
column (informational, §8) is kept. Replayability lives **solely** on
`run.snapshot_json`. Re-introducing `ttp_version` requires explicit spec amendment
through the team-lead.