docs: de-link spike findings from spike/ code (moved to private repo)

docs/design/spike-block2-findings.md

@@ -1,9 +1,9 @@
 # Spike — Block 2 (social layer) de-risking findings
 
 *Throwaway research spike. Language: English (findings), per code convention.
-Code lives in [`spike/block2_spike/`](../../spike/block2_spike/) and is marked
-throwaway — **not production, not on the pub workspace, no deps added to Block
-1**. This document is the deliverable: what we learned, the risks, and a
+The throwaway spike code (`spike/block2_spike/`) has been moved out of this
+public repo and preserved privately — it was **not production, not on the pub
+workspace, no deps added to Block 1**. This document is the deliverable: what we learned, the risks, and a
 recommendation on whether/how to take on the social round (Phase 3).*
 
 > **Status: this is a spike, not a green light to build Block 2.** CLAUDE.md and
@@ -34,7 +34,7 @@ See "How to run" at the end.
 
 **Result: works, deterministic, one-way. This unblocks "one identity, one backup".**
 
-- Implemented [`NostrKey.deriveFromSeed`](../../spike/block2_spike/lib/src/nostr_key.dart):
+- Implemented `NostrKey.deriveFromSeed`:
   `HKDF-SHA256(rootSeed, info: "org.comunes.tane/nostr/secp256k1/v1")` → reduce
   to a valid secp256k1 scalar `d ∈ [1, n-1]` by rejection (bump a counter in the
   HKDF info on the astronomically-rare miss, so the result stays a pure function
@@ -80,13 +80,13 @@ trust do NOT fit behind the same interface — they share a *connection*, not a
 *contract*.**
 
 ### The seam works (offers)
-- [`OfferTransport`](../../spike/block2_spike/lib/src/offer_transport.dart) =
+- `OfferTransport` =
   `publish(Offer)` / `discover(DiscoveryQuery)` / `retract(id)`. The Nostr
-  NIP-99 backend ([`NostrOfferTransport`](../../spike/block2_spike/lib/src/nostr_offer_transport.dart)
-  + [`Nip99Codec`](../../spike/block2_spike/lib/src/nip99.dart)) sits entirely
+  NIP-99 backend (`NostrOfferTransport`
+  + `Nip99Codec`) sits entirely
   behind it. A second backend (ActivityPub/FEP-0837) could replace it without
   the domain noticing.
-- [`Offer`](../../spike/block2_spike/lib/src/offer.dart) is agnostic by
+- `Offer` is agnostic by
   construction: a chosen *summary* + coarse geohash, **no FK into seed tables,
   no full inventory, no exact address** — exactly the Offer↔Lot split
   [sharing-model.md](sharing-model.md) §2 and
@@ -114,14 +114,14 @@ manageable**:
   private encrypted DM vs. assert/read a signed certification. Forcing DMs and
   certifications behind `OfferTransport.publish/discover` would overload it.
 - **Recommendation — now demonstrated in code, not just asserted:**
-  [`NostrConnection`](../../spike/block2_spike/lib/src/nostr_connection.dart) is
+  `NostrConnection` is
   **one shared** socket + key + sign + REQ/EOSE lifecycle, and **all three thin
   interfaces sit on top of the same instance** —
-  [`OfferTransport`](../../spike/block2_spike/lib/src/nostr_offer_transport.dart)
+  `OfferTransport`
   (NIP-99),
-  [`MessageTransport`](../../spike/block2_spike/lib/src/nostr_message_transport.dart)
+  `MessageTransport`
   (NIP-17) and
-  [`TrustTransport`](../../spike/block2_spike/lib/src/nostr_trust_transport.dart)
+  `TrustTransport`
   (custom WoT). The trust test even runs offer discovery and trust annotation
   over one connection. This is the shape to lift into `commons_core`: shared
   connection, per-concern contract. Trying to make `OfferTransport` also carry
@@ -139,7 +139,7 @@ that whole happy path now runs — what's left is production hardening (below).
 **Result: the flow works end to end. The real risk is NIP maturity/ecosystem,
 not the mechanics.**
 
-- Built a hermetic in-process [`MiniRelay`](../../spike/block2_spike/lib/src/mini_relay.dart)
+- Built a hermetic in-process `MiniRelay`
   (NIP-01 subset: EVENT/REQ/EOSE/CLOSE, filter by `kinds`/`authors`/`#g`,
   addressable-event replacement for kind 30402). No network → CI-safe, no flaky
   public-relay dependency.
@@ -183,13 +183,13 @@ The plan ([network-trust.md](network-trust.md) §4) calls messaging "grande" and
 [open-decisions.md](open-decisions.md) §D.3 singled it out as the tightest
 coupling to Nostr. So the spike built it rather than hand-waving:
 
-- **NIP-44 v2 encryption** ([`Nip44`](../../spike/block2_spike/lib/src/nip44.dart)):
+- **NIP-44 v2 encryption** (`Nip44`):
   secp256k1 ECDH → HKDF conversation key → ChaCha20 + HMAC-SHA256 with
   length-hiding padding. Conversation key is symmetric (A→B == B→A, tested); a
   wrong key cannot decrypt (throws, tested); short messages pad to the same
   bucket so ciphertext length doesn't leak plaintext length (tested).
 - **NIP-17 / NIP-59 gift-wrap onion**
-  ([`NostrMessageTransport`](../../spike/block2_spike/lib/src/nostr_message_transport.dart)):
+  (`NostrMessageTransport`):
   rumor (kind 14, unsigned) → seal (kind 13, signed by sender, NIP-44 to
   recipient) → gift wrap (kind 1059, signed by a **throwaway ephemeral key**,
   NIP-44 to recipient).
@@ -223,12 +223,12 @@ There is no settled NIP for a web of trust, so — exactly as
 anticipates — the spike models **its own WoT, Duniter-compatible**, over Nostr:
 
 - **Certifications as events**
-  ([`NostrTrustTransport`](../../spike/block2_spike/lib/src/nostr_trust_transport.dart)):
+  (`NostrTrustTransport`):
   a custom addressable kind (30777) keyed by (issuer, `d`=subject), so one live
   "A vouches for B" per pair; re-certifying renews, revoking replaces (tested).
   Certifications expire (Ğ1 semantics) and are public (like the on-chain Ğ1 WoT).
 - **The membership rule is pure and separately tested**
-  ([`WebOfTrust`](../../spike/block2_spike/lib/src/web_of_trust.dart)) — the
+  (`WebOfTrust`) — the
   `commons_core`-worthy piece: Duniter's two rules, **N certifications from
   existing members** (sigQty) and **within distance D of the bootstrap
   referents** (stepMax), iterated to a fixpoint (becoming a member can push
@@ -263,8 +263,9 @@ entity, and optionally importing the on-chain Ğ1 WoT (level 3) as a trust sourc
    ([open-decisions.md](open-decisions.md) §D.1, §D.6). That is what should drive
    the Phase-3 estimate and the funding ask.
 4. **Do not start Block 2 from this spike.** It is throwaway research code (not
-   vector-verified, no offline delivery, no persistence, single relay). Delete
-   `spike/block2_spike/` once these findings are absorbed. The funded social
+   vector-verified, no offline delivery, no persistence, single relay). The
+   `spike/block2_spike/` code has been moved out of this public repo (preserved
+   privately) now these findings are captured. The funded social
    round should **rebuild on vetted client libraries in `commons_core`**, using
    the shapes proven here — one `NostrConnection`, three interfaces, the pure
    `WebOfTrust` rule — and spend its risk budget on hardening and bootstrap, not
@@ -283,11 +284,12 @@ entity, and optionally importing the on-chain Ğ1 WoT (level 3) as a trust sourc
 
 ## How to run
 
+The throwaway spike code has been moved out of this public repo and is preserved
+privately; nothing here was wired into `app_seeds` or `commons_core`'s production
+graph, and the Block 1 suite is untouched. For the record, it ran as:
+
 ```sh
-cd spike/block2_spike
+cd spike/block2_spike   # in the private archive
 dart pub get
 dart test   # derivation · privacy · roundtrip · messaging · trust · web_of_trust  (30 tests)
 ```
-
-Nothing here is wired into `app_seeds` or `commons_core`'s production graph; the
-Block 1 suite is untouched.