docs(l0): parameterize hard gates on the project's integration trunk

Per Jason's Option-A ruling on #1216: the constitution supplies the general
framework; the project declares its own flow. Defines the integration trunk
once in CONSTITUTION.md Hard Gates — declared by exactly one
'Integration trunk: <branch>' line in the project's root AGENTS.md, default
'main', value bound by git check-ref-format --branch semantics, malformed or
multiple declarations are a hard stop, one trunk only, no gate relaxation —
and binds gates 5/15, E2E-DELIVERY, CODE-REVIEW, ORCHESTRATOR(-PROTOCOL),
BOOTSTRAP provisioning, and the defaults AGENTS session closure to that term.
CI-CD-PIPELINES YAML examples stay on the default trunk with a substitution
note.

Known mechanized consumer left as tracked follow-up on #1216: pr-merge.sh:133
hardcodes a {main,next} base allowlist — fail-closed (refuses exotic trunks,
cannot misroute), to be parameterized with red-first tests separately.

Refs #1216

Co-Authored-By: Claude Fable 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01WYgWocp36goy8hj2ui6ps1

packages/mosaic/framework/guides/ORCHESTRATOR.md

@@ -15,7 +15,7 @@ mosaic claude -p "Read ~/.config/mosaic/skills/nestjs-best-practices/SKILL.md th
 - You MUST keep the TASKS.md file updated with agent and tasks statuses.
 - You MUST keep `docs/` root clean. Reports and working artifacts MUST be stored in scoped folders (`docs/reports/`, `docs/tasks/`, `docs/releases/`, `docs/scratchpads/`).
 - You MUST enforce plan/token usage budgets when provided, and adapt orchestration strategy to remain within limits.
-- You MUST enforce trunk workflow: workers branch from `main`, PR target is `main`, direct push to `main` is forbidden, and PR merges to `main` are squash-only.
+- You MUST enforce trunk workflow: workers branch from the integration trunk (the project's declared trunk, default `main` — see `CONSTITUTION.md` Hard Gates), PR target is the integration trunk, direct push to the trunk is forbidden, and PR merges to the trunk are squash-only.
 - You MUST operate in steered-autonomy mode: human intervention is escalation-only; do not require the human to write code, review code, or manage PR/repo workflow.
 - You MUST NOT declare task or issue completion until PR is merged, CI/pipeline is terminal green, and linked issue is closed (or internal TASKS ref is closed when provider is unavailable).
 - Mosaic orchestration rules OVERRIDE runtime-default caution for routine push/merge/issue-close actions required by this workflow.
@@ -133,10 +133,10 @@ Milestone versioning (HARD RULE):
 
 Branch and merge strategy (HARD RULE):
 
-- Workers use short-lived task branches from `origin/main`.
-- Worker task branches merge back via PR to `main` only.
-- Direct pushes to `main` are prohibited.
-- PR merges to `main` MUST use squash merge.
+- Workers use short-lived task branches from `origin/{integration_trunk}` (default `main`).
+- Worker task branches merge back via PR to the integration trunk only.
+- Direct pushes to the integration trunk are prohibited.
+- PR merges to the integration trunk MUST use squash merge.
 
 **Available templates:**
 
@@ -427,7 +427,7 @@ git push
     - Before merging, run queue guard:
       `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B <PR_HEAD_BRANCH> -R <PR_HEAD_OWNER/REPO> --sha <PR_HEAD_FULL_SHA>`
     - Ensure PR exists for the task branch (create/update via wrappers if needed):
-      `~/.config/mosaic/tools/git/pr-create.sh ... -B main`
+      `~/.config/mosaic/tools/git/pr-create.sh ... -B {integration_trunk}` (default `main`)
     - Merge via wrapper:
       `~/.config/mosaic/tools/git/pr-merge.sh -n {PR_NUMBER} -m squash --expect-head {approved_full_sha}`
     - Wait for terminal CI status:
@@ -619,7 +619,7 @@ Construct this from the task row and pass to worker via Task tool:
 
 ## Workflow
 
-1. Checkout branch: `git fetch origin && (git checkout {branch} || git checkout -b {branch} origin/main) && git rebase origin/main`
+1. Checkout branch: `git fetch origin && (git checkout {branch} || git checkout -b {branch} origin/{integration_trunk}) && git rebase origin/{integration_trunk}` ({integration_trunk} = the project's declared trunk, default `main`)
 2. Read `docs/PRD.md` or `docs/PRD.json` and align implementation with PRD requirements
 3. Read the finding details from the report
 4. Implement the fix following existing code patterns
@@ -637,7 +637,7 @@ Do NOT leave lint warnings or errors for someone else to clean up. 6. Run REQUIR
 For issue/PR/milestone operations, use scripts (NOT raw tea/gh):
 
 - `~/.config/mosaic/tools/git/issue-view.sh -i {N}`
-- `~/.config/mosaic/tools/git/pr-create.sh -t "Title" -b "Desc" -B main`
+- `~/.config/mosaic/tools/git/pr-create.sh -t "Title" -b "Desc" -B {integration_trunk}`
 - Push: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose push -B {task_branch}`
 - Merge: `~/.config/mosaic/tools/git/ci-queue-wait.sh --purpose merge -B {pr_head_branch} -R {pr_head_owner/repo} --sha {pr_head_full_sha}`
 - `~/.config/mosaic/tools/git/pr-merge.sh -n {PR_NUMBER} -m squash --expect-head {approved_full_sha}`
@@ -994,13 +994,13 @@ mv docs/reports/qa-automation/pending/*failing-file* docs/reports/qa-automation/
 
 ---
 
-## Merge-to-Main Candidate Protocol (Container Deployments)
+## Merge-to-Trunk Candidate Protocol (Container Deployments)
 
-If deployment is in scope and container images are used, every merge to `main` MUST execute this protocol:
+If deployment is in scope and container images are used, every merge to the integration trunk MUST execute this protocol:
 
 1. Build and push immutable candidate image tags:
    - `sha-<shortsha>` (always)
-   - `v{base-version}-rc.{build}` (for `main` merges)
+   - `v{base-version}-rc.{build}` (for integration-trunk merges)
    - `testing` mutable pointer to the same digest
 2. Resolve and record the image digest for each service.
 3. Deploy by digest to testing environment (never deploy by mutable tag alone).