docs: PRD for forge subroles (per-bottle subuser identity & vouched attribution)

Formalizes the design settled in issue #423: one forge subrole identity
per bottled agent (author + forge account + SSH signing key), reused
across all repos/forges. Vouched attribution via sign-at-commit-time in
the git-gate boundary (forwarded ssh-agent; private key never in the
bottle; no SHA divergence). Forge "Verified" badges abandoned in favor
of local git verify-commit plus durable console audit records and
commit-status badges. Reprovision-per-activation credential lifecycle
(0048 discipline), fail-loud teardown, public-key-fingerprint-only audit
trail on bottled_agent.

Successor to PRD 0027 (claimed-not-vouched, ADR 0002) and PRD 0048
(host-side minting lifecycle).

Issue: #423

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/prds/prd-new-forge-subroles.md

@@ -0,0 +1,433 @@
+# PRD prd-new: Forge subroles — per-bottle subuser identity & vouched commit attribution
+
+- **Status:** Draft
+- **Author:** didericis-claude
+- **Created:** 2026-07-25
+- **Issue:** #423
+
+## Summary
+
+Give each bottled agent a **forge subrole**: a single, per-instance identity on
+a git forge (Gitea today) with a distinct forge account, a strictly-scoped API
+token, per-repo push credentials, and — the point of the whole thing —
+**vouched** commit attribution via SSH commit signing performed in the git-gate
+trust boundary, outside the bottle. Author name/email, forge account, and
+signing key are one identity per bottled agent, reused across every repo and
+every forge that bottle touches. All credential material is minted host-side at
+spin-up, reaches the sidecar but never the bottle, and is revoked at teardown
+(PRD 0048 discipline). Old key fingerprints and activation/deactivation cycles
+are retained on the `bottled_agent` table as a durable audit trail.
+
+This is the "identity" successor to the two PRDs that set it up:
+
+- **PRD 0027 (agent git identity, #94)** established that `git-gate.user`
+  name/email is *claimed, not vouched* (ADR 0002) — forgeable, cosmetic, and
+  explicitly deferred the integrity question to "a commit-*signing* concern
+  (SSH/GPG)." This PRD is that signing concern; it makes authorship
+  cryptographically vouched and closes the door ADR 0002 left open.
+- **PRD 0048 (deploy-key provisioning, #169)** established the host-side
+  provisioner pattern: a developer-held minting credential mints short-lived,
+  per-spin-up, revoked-at-teardown key material that reaches the sidecar but
+  never the bottle. Subrole credentials follow the same lifecycle.
+
+## Problem
+
+An agent runs on the developer's own machine and inherits the machine's trust,
+scoped down per role — a *subrole*, not a new principal. That works locally
+because the machine is single-tenant. A **git forge is the one shared,
+multi-user layer** where a distinct identity actually earns its keep, and today
+bot-bottle has none:
+
+- **Attribution is unvouched.** A bottle commits under whatever `git-gate.user`
+  name/email the manifest declares, which ADR 0002 accepts as forgeable and
+  cosmetic. On a shared forge there is no way to tell a real commit by the
+  subrole from a spoof, and no tamper-evidence on the history the agent
+  produced.
+- **There is no independent identity to revoke.** Push happens under the
+  bottle's deploy key (0048), but there is no forge *account* for the subrole
+  whose access can be granted, scoped, and killed without touching the
+  developer's own account.
+- **Forge API actions borrow the developer's hand.** Commenting on an issue,
+  opening a PR, or labeling is done — if at all — as the developer, not as a
+  scoped subrole with its own least-privilege token.
+
+The naming convention already in use — `didericis-claude`, `didericis-codex`
+(prefix = lineage/ownership, suffix = subrole) — anticipates this. The identity
+must be **keyed to the bottled agent** (the trust/credential boundary), not
+derived from the provider template; today's provider-shaped names are just the
+special case where the bottle happens to be one-provider. Nothing should
+*derive* the forge username from the provider (the current code does not — only
+the container image tag is provider-derived, which is correct).
+
+## Goals / Success Criteria
+
+- **One identity per bottled agent.** A single author name/email, a single
+  forge account per forge, and a single SSH signing key serve every repo and
+  every forge the bottle touches. The manifest cannot express two identities
+  for one bottled agent.
+- **Vouched attribution.** Commits produced in the bottle carry a valid SSH
+  signature (`git verify-commit` succeeds against the retained public key) with
+  no commit-SHA divergence between agent-space and the signed upstream.
+- **Private signing key never enters the bottle.** Only a bounded signing
+  capability (a forwarded `ssh-agent` socket) crosses the boundary.
+- **Scoped, independently-revocable forge access.** The subrole is a strict
+  subset of the developer's forge access: a scoped collaborator/account with a
+  forge-scoped, least-privilege API token (commenting, issues, PRs, labeling)
+  and per-repo push credentials.
+- **Reprovision-per-activation lifecycle.** Push credentials, API token, and
+  signing key are freshly minted on each activation and revoked at teardown;
+  failure to revoke halts teardown loudly (0048). This avoids credential
+  accumulation across frozen snapshots.
+- **Durable audit trail.** Each activation/deactivation cycle and every retired
+  key is recorded on the `bottled_agent` table as a **public-key fingerprint
+  only** — never private key material.
+- **Fail-closed provisioning.** A bottle that declares a forge (via
+  `git-forge` or a `git-gate.repos` entry) with no corresponding
+  `agent.forge-accounts` entry fails provisioning with a clear error rather
+  than launching with a half-configured identity.
+- **Least-privilege, host-only minting credential.** The credential that mints
+  subrole material can create/delete keys and tokens for owned repos/accounts —
+  *not* act as instance admin — and never enters the bottle.
+
+## Non-goals
+
+- **Non-Gitea forges.** GitHub and GitLab both support SSH signing keys and
+  commit-status APIs and are a natural fit, but each is a future
+  `bot_bottle/contrib/<forge>/` sub-package. This PRD ships Gitea only.
+- **Forge-rendered "Verified" badges.** Deliberately abandoned — see Design.
+  Vouched-ness is carried by local `git verify-commit` plus a durable console
+  audit record and (optionally) a commit-status badge, not by the forge's
+  ephemeral signature UI.
+- **Design B forge-visible pusher identity.** We keep repo-scoped deploy keys
+  for push *capability* (0048 unchanged) and get vouched *authorship* from
+  signing. Making the forge *pusher* record itself the subrole (subuser-owned
+  push keys, broader account/collaborator minting) is a larger surface deferred
+  until a forge-visible pusher is an actual requirement.
+- **Dirty-teardown reconciliation.** We assume clean teardown for now. A
+  separate cleanup/sync pass reconciles orphaned forge credentials left by a
+  crash or a frozen-then-discarded snapshot; it is out of scope here.
+- **Dashboard UI** for listing or revoking orphaned subrole credentials.
+- **Rotation mid-session.** Credentials live for exactly one
+  activation→teardown cycle, as in 0048.
+- **Generalizing the minting credential into the full `SecretProvider`
+  (#355).** This PRD consumes the existing provisioned-secret reference shape;
+  it does not build the general provider surface.
+
+## Design
+
+### Identity model
+
+An identity is realized per **bottled agent** (an agent definition composed
+with its sealed bottle). It has three parts, all sharing one lifecycle:
+
+| Part | Value | Where declared | Scope |
+|------|-------|----------------|-------|
+| Author | name + email | agent file (`author`) | commit author string |
+| Forge account | subuser per forge | agent file (`forge-accounts`) | API token owner, PR/issue/label actor |
+| Signing key | one SSH (Ed25519) keypair | minted, not declared | signs every commit, all repos/forges |
+
+The same author string and the same signing key are used for **all** repos and
+**all** forges the bottle touches — there is exactly one identity per bottled
+agent. Which forge *account* to act as is per-forge (a bottle may touch more
+than one forge), so `forge-accounts` is a map.
+
+### Manifest surface
+
+The identity splits across the two manifest files along the existing trust
+boundary (ADR 0002, PRD 0047): **identity claims live in the agent file**
+(overlayable, cosmetic-until-vouched), **forge connections and credential
+material live in the bottle file** (home-only, credential-bearing).
+
+**Agent file** — the identity this bottled agent claims:
+
+```yaml
+author:
+  name: didericis-claude
+  email: eric+claude@dideric.is
+forge-accounts:
+  gitea: didericis-claude        # forge name → subuser account
+```
+
+**Bottle file** — how to reach each forge, and which repos the gate exposes:
+
+```yaml
+git-forge:
+  gitea:                          # forge name (referenced by repos + accounts)
+    type: gitea
+    ssh:
+      url: ssh://git@100.78.141.42:30009
+      host_key: "ssh-ed25519 AAAA..."
+    api:
+      url: https://gitea.dideric.is/api/v1
+      auth:
+        scheme: token
+        token_secret:
+          type: provisioned       # the subrole's API token, minted per-activation
+      provisioner_secret: GITEA_ADMIN_TOKEN   # host-only minting credential
+git-gate:
+  repos:
+    bot-bottle:
+      type: forge-repo
+      forge: gitea                # references git-forge.gitea
+      organization: didericis
+      identity_secret:
+        type: provisioned         # per-repo push deploy key, minted per-activation (0048)
+```
+
+Notes on the shape:
+
+- `git-forge.<name>` is a new bottle-only block describing one forge: its SSH
+  endpoint (for push, with a pinned `host_key`) and its API endpoint (for
+  subrole actions and commit-status). `provisioner_secret` names a **host env
+  var** holding the least-privilege minting credential; it is resolved at
+  provision time and never stored in the plan or seen by the bottle (same
+  discipline as `token_env` in 0048).
+- `token_secret: { type: provisioned }` and `identity_secret: { type:
+  provisioned }` are secret *references*, not secret values. `provisioned`
+  means "bot-bottle mints this at spin-up." This is the same reference shape the
+  SecretProvider work (#355) generalizes; here we implement only the
+  `provisioned` case. A future `type: env` / `type: static` can slot in for
+  operator-supplied material, mirroring 0048's `identity:` escape hatch.
+- `git-gate.repos.<name>` moves from carrying a raw `url`/`identity` (PRD 0047)
+  to referencing a named forge plus `organization`; the gate derives the push
+  URL from `git-forge.<forge>.ssh.url` + `organization` + repo name. This keeps
+  the forge endpoint declared once and reused. Operator-supplied static repos
+  (0048 `identity:` / 0047 `url:`) remain valid for repos that opt out of the
+  forge-subrole machinery.
+
+The `author`/`forge-accounts` keys are added to `AGENT_KEYS_OPTIONAL`;
+`git-forge` is added to `BOTTLE_KEYS`. Whether `author`/`forge-accounts` should
+nest under `git-gate:` (per 0047's "consolidate all git config under one key")
+or stay top-level as sketched here is an open question below.
+
+### Provisioning validation (fail-closed)
+
+At seal/prepare time, before any container starts:
+
+1. Every forge referenced by a `git-gate.repos[*].forge` and every key in
+   `git-forge` **must** have a matching entry in the agent's `forge-accounts`.
+   A bottle that declares a forge without an agent account fails with:
+
+   ```
+   bottle 'dev' declares forge 'gitea' (git-forge / git-gate.repos['bot-bottle'])
+   but agent 'implementer' has no forge-accounts entry for it. A forge subrole
+   requires a forge account; add `forge-accounts: { gitea: <account> }`.
+   ```
+
+2. `author.name` and `author.email` must both be non-empty when any forge is
+   declared (a vouched identity needs an author string to vouch for).
+
+3. Each `provisioner_secret` env var must be present in the host environment;
+   absence fails loud rather than silently skipping provisioning.
+
+### Signing: sign at commit time via a forwarded ssh-agent
+
+The core constraint (issue #423, comment #4321): signing must happen **in the
+git-gate trust boundary, not in the bottle**, yet the commit SHA must be final
+at commit time so agent-space and the signed upstream never diverge.
+
+Chosen mechanism:
+
+- The **sidecar** (already the git-gate trust boundary, outside the bottle)
+  runs an `ssh-agent` holding the short-lived signing private key.
+- **Only `SSH_AUTH_SOCK` is forwarded** into the bottle — a bounded signing
+  *capability*, not the key. The private key never has a representation inside
+  the bottle's filesystem or memory.
+- The bottle's `.gitconfig` (written by the provisioner) sets:
+
+  ```ini
+  [commit]
+      gpgsign = true
+  [gpg]
+      format = ssh
+  [user]
+      signingkey = ssh-ed25519 AAAA...   # the subrole signing PUBLIC key
+  ```
+
+- `git commit` in the bottle asks the forwarded agent to sign; the signature is
+  embedded in the commit object at creation. The SHA the agent sees **is** the
+  SHA that reaches the upstream through the gate. No transcoding, no SHA
+  translation table, no divergence.
+
+`git verify-commit` succeeds anywhere that has the subrole public key, which is
+retained in the audit record (below).
+
+### Attribution surface: no forge "Verified" badge
+
+Forge-rendered "Verified" badges are **intentionally abandoned**. Two reasons,
+both established in the issue thread:
+
+1. **They are ephemeral.** Gitea (and the others) render the badge dynamically
+   at display time by matching the commit signature against a *currently
+   registered* signing key. Because subrole signing keys are reprovisioned and
+   revoked every activation cycle, a forge-registered key would show
+   "unverified" as soon as the bottle tears down — the badge would lie about
+   history the moment the session ends.
+2. **We don't want to register signing keys on the forge at all.** Registering
+   a signing key on Gitea also grants push access (Gitea does not separate
+   signing keys from access keys), coupling a presentation concern to a
+   capability. Push is already handled by scoped deploy keys (0048); the
+   signing key should carry no forge access.
+
+Instead, vouched-ness is surfaced two durable ways:
+
+- **Local verification.** `git verify-commit <sha>` against the retained public
+  key is the ground truth and survives independent of any forge.
+- **Commit-status badge (optional, per-forge).** The orchestrator/console posts
+  a commit *status* via the forge API (all three forges expose this and it
+  persists server-side permanently): `pending` when the commit is observed,
+  `success` at clean teardown, with a `target_url` pointing at the durable
+  console audit record. This is posted using the subrole's API token, so the
+  badge is attributed to the subrole, and it does not depend on any key still
+  being registered.
+
+### Credential lifecycle
+
+Follows PRD 0048's mint-at-spin-up / revoke-at-teardown discipline, extended to
+three credential kinds and made **reprovision-per-activation**:
+
+**At activation (spin-up), host-side, using each forge's `provisioner_secret`:**
+
+1. Mint a fresh Ed25519 **signing** keypair. Load the private half into the
+   sidecar `ssh-agent`; write the public half into the bottle `.gitconfig`
+   `user.signingkey` and into the audit record (fingerprint).
+2. Mint a fresh **API token** for the subrole account, forge-scoped to the
+   minimum: commenting, creating issues, creating PRs, labeling issues.
+   Resolves the `token_secret: { type: provisioned }` reference. Held host/
+   sidecar-side for commit-status and forge actions; never handed to the
+   bottle raw (the bottle reaches the forge API through the gate/broker).
+3. Mint fresh per-repo **push deploy keys** for every `git-gate.repos` entry
+   whose `identity_secret` is `provisioned` — exactly PRD 0048's
+   `DeployKeyProvisioner.create`.
+
+Keys are **generated once per activation and persist across restarts** within
+that activation (a restart re-attaches the same minted material, it does not
+re-mint). Re-minting happens on a *new* activation. This is deliberate: minting
+per-restart would pile up dead keys on the forge for every frozen snapshot;
+minting per-activation keeps exactly one live key set per running bottled agent.
+
+**At teardown (fail-loud, 0048):**
+
+- Delete the API token and every provisioned deploy key via the forge API.
+- Discard the signing key from the sidecar `ssh-agent` (it was never on the
+  forge, so there is nothing to revoke there — but its fingerprint is retired
+  in the audit trail).
+- Any deletion failure **halts teardown and propagates loudly** (404 =
+  already-gone = success, per 0048).
+- We **assume clean teardown.** Dirty teardown (crash, discarded frozen
+  snapshot) may orphan forge credentials; a separate cleanup/sync pass
+  reconciles those and is out of scope here.
+
+### Audit trail on `bottled_agent`
+
+The host SQLite store (PRD 0067, `~/.bot-bottle/bot-bottle.db`) gains a
+`bottled_agent`-scoped record of the identity lifecycle. Every activation and
+deactivation is recorded, and **retired** keys are kept so history stays
+attributable after rotation. Only **public-key fingerprints** are ever stored —
+never private key material, never the API token value.
+
+Illustrative shape (subject to alignment with the forge-orchestration tables
+0067 anticipated):
+
+```sql
+CREATE TABLE bottled_agent_identity (
+    bottled_agent_slug TEXT NOT NULL,
+    activation_id      TEXT NOT NULL,     -- one per activation cycle
+    forge              TEXT NOT NULL,     -- e.g. 'gitea'
+    forge_account      TEXT NOT NULL,     -- e.g. 'didericis-claude'
+    author_name        TEXT NOT NULL,
+    author_email       TEXT NOT NULL,
+    signing_key_fpr    TEXT NOT NULL,     -- SHA256:... public-key fingerprint
+    activated_at       TEXT NOT NULL,
+    deactivated_at     TEXT,              -- NULL while active
+    status             TEXT NOT NULL,     -- active | retired
+    PRIMARY KEY (bottled_agent_slug, activation_id, forge)
+);
+```
+
+This table is the `target_url` destination for commit-status badges and the
+source of truth for "which key signed this commit, and when was that identity
+live."
+
+## Alternatives considered
+
+- **Stateless reversible transcoder (issue #423, comment #4321, Solution 2).**
+  Strip/re-apply the `gpgsig` header on fetch/push with deterministic signing
+  and an in-memory SHA translation table. Rejected: it introduces a SHA
+  divergence between agent-space and remote-space that must be maintained for
+  the life of the session, with no persistence story across restarts.
+  Sign-at-commit-time keeps SHAs identical and needs no translation state.
+- **Register the signing key on the forge for a "Verified" badge (original
+  issue sketch).** Rejected: badges are rendered dynamically and vanish when
+  the reprovisioned key is revoked; on Gitea a signing key also grants push,
+  coupling presentation to capability. See "Attribution surface" above.
+- **Design B: subuser-owned push keys / forge pusher = subrole.** Deferred;
+  larger account- and collaborator-management surface with a broader minting
+  token, not required to get vouched authorship.
+
+## Implementation chunks
+
+1. **This PRD.** Sets the design.
+2. **Manifest surface + validation.** Add `author` / `forge-accounts` to agent
+   keys; add `git-forge` to bottle keys; parse the provisioned-secret reference
+   shape; restructure `git-gate.repos` to reference a named forge +
+   organization while keeping 0047/0048 static entries valid. Fail-closed
+   checks (forge-without-account, missing author, missing `provisioner_secret`).
+   Unit tests for each parse/validation path.
+3. **Signing pipeline.** Sidecar `ssh-agent` provisioning; forward
+   `SSH_AUTH_SOCK` into the bottle across docker, smolmachines, macOS-container,
+   and firecracker backends; emit the `commit.gpgsign` / `gpg.format=ssh` /
+   `user.signingkey` gitconfig. Integration test: a bottle commit is
+   `git verify-commit`-valid and its SHA is unchanged through the gate.
+4. **Forge-account provisioning (Gitea contrib).** Extend
+   `bot_bottle/contrib/gitea/` with API-token minting (scoped: comment, issue,
+   PR, label) and revocation, reusing the `provisioner_secret` custody model.
+   Wire the signing-key and API-token lifecycle into the same
+   activation/teardown hooks as `DeployKeyProvisioner`.
+5. **Audit + commit-status.** `bottled_agent_identity` table (PRD 0067 store);
+   record activation/deactivation and retired-key fingerprints; post
+   commit-status badges (`pending` → `success`) with `target_url` to the audit
+   record.
+6. **Docs.** Glossary entry for "Forge Subrole"; README manifest section;
+   ADR update noting authorship is now *vouched* for signed bottled agents
+   (superseding the ADR 0002 posture for this path).
+
+## Testing strategy
+
+- **Unit (must):** manifest parse/validation matrix — `author` +
+  `forge-accounts` on the agent; `git-forge` on the bottle; provisioned-secret
+  references; the fail-closed cases (forge without account, empty author,
+  absent `provisioner_secret`); `git-gate.repos` forge-reference resolution
+  alongside surviving 0047/0048 static entries.
+- **Integration (must):** end-to-end signed commit — bottle commits, the
+  signature verifies with `git verify-commit`, and the SHA observed in the
+  bottle equals the SHA that lands upstream through the gate. Private key is
+  absent from the bottle filesystem/agent-visible memory.
+- **Lifecycle (must):** activation mints signing key + API token + deploy keys;
+  teardown revokes all three and halts loudly on a forced API failure; the
+  `bottled_agent_identity` row transitions `active` → `retired` with only a
+  fingerprint stored.
+- **Reprovision-per-activation:** a restart re-attaches the same key set (no new
+  forge key); a fresh activation mints a new set and retires the old
+  fingerprint.
+
+## Open questions
+
+- **Key placement in the manifest.** Do `author` / `forge-accounts` stay
+  top-level on the agent file (as sketched by the owner in #4927), or nest under
+  `git-gate:` to honor PRD 0047's "consolidate all git configuration under one
+  key"? The former reads cleaner; the latter is more consistent. Resolve before
+  chunk 2.
+- **Where does the commit-status poster run?** The orchestrator/console holds
+  the API token host-side and is the natural poster, but it must observe new
+  commit SHAs. Is that a gate push-hook callback, or a poll? (Ties into the
+  forge-orchestration work 0067 anticipated.)
+- **Provisioner-secret naming.** `GITEA_ADMIN_TOKEN` reads as instance-admin,
+  but the constraint is least-privilege (create/delete keys + tokens for owned
+  repos/accounts, *not* admin). Rename to `GITEA_MINT_TOKEN` (per the issue
+  body) to avoid implying more privilege than the credential should carry?
+- **Signing-key fingerprint vs. full pubkey in the audit record.** The thread
+  settled on "public-key fingerprint" for the audit trail, but `git
+  verify-commit` needs the full public key. Store both (full pubkey for
+  verification, fingerprint as the stable handle), or reconstruct verification
+  material elsewhere?