refactor(bundle): rename built-in bundle to amplifier-agent-anchors

[Salil Das (sadlilas)]

Why

The built-in bundle is called amplifier-agent-behavioral-anchor. That name is a fossil.

Date	Event
2026-06-03	amplifier-foundation adds experiments/behavioral-anchor
2026-06-17	this repo vendors it at v0.7.0, naming the bundle amplifier-agent-behavioral-anchor
2026-06-23	foundation promotes it to the published anchors bundle (bundles/anchors/)
2026-07-22	upstream registers the skills-bundle skills source
2026-08-03	upstream composes Context Intelligence by default

We vendored the experiment six days before it was renamed, and every reference here has pointed at the pre-promotion name ever since.

Part 1 — the rename

amplifier-agent-behavioral-anchor → amplifier-agent-anchors. The amplifier-agent- prefix is this repo's convention (the name before this one was amplifier-agent-builtin) and keeps the vendored variant distinct from foundation's anchors.

Six references move together, because the three @mentions resolve against the bundle's own name:

File	What
src/amplifier_agent_lib/bundle/bundle.md	bundle.name
src/amplifier_agent_lib/bundle/bundle.md	@…:skills in tool-skills.config.skills
src/amplifier_agent_lib/bundle/bundle.md	@…:modes in hooks-mode.config.search_paths
src/amplifier_agent_lib/bundle/bundle.md	@…:context/system.md — the system prompt load
scripts/verify-wheel.py	the bundle-name assertion (would fail CI otherwise)
docs/LAYERS_AND_RELEASES.md	the documented bundle name

@…:skills and @…:modes have a safety net — _runtime.py prepends the absolute BUNDLE_DIR/skills and BUNDLE_DIR/modes paths, built-ins winning first-match. @…:context/system.md has none. A mismatch there means the principle-led system prompt silently fails to load, which is why all six are in one commit.

Part 2 — re-point the upstream comparison, and re-diff it

The manifest's "AAA-specific modifications from upstream" table diffed against experiments/behavioral-anchor/behavioral-anchor.md — a file frozen since June. Anyone reconciling this bundle against upstream has been reading the wrong file for two months.

Seven references now point at bundles/anchors/bundle.md, across bundle.md, bundle/__init__.py, and docs/spec/bundle-and-cache.md. More importantly, the table has been rewritten from an actual comparison rather than re-pointed and left stale. What changed:

Newly recorded as AAA additions (upstream has neither, and neither was in the old table):

• 9 provider install-stubs. Upstream declares no providers at all. The engine needs them present so prepare(install_deps=True) clones and installs each one.
• hooks-routing — the model-role routing matrix, inlined per Strategy 1 rather than included from @routing-matrix.

Reclassified from "addition" to "divergence":

• Context Intelligence. The old table presented hook-context-intelligence as something we added on top of an upstream that lacked it. Upstream has composed it by default since 2026-08-03, as two behavior includes — logging and navigation. We declare the hook module inline and take the logging half only, so we do not get the session-navigator agent. The workspace-JSONL-alignment rationale (invariant I8) is unchanged.

Newly recorded divergence:

• Skills sources. Upstream registers the amplifier-bundle-skills skills directory so its /command skills resolve. We vendor a curated subset inside the wheel instead — code-review, council, and the 6 council lenses — injected by _runtime.py as an absolute path. Consequence, now stated explicitly: council-here, mass-change, session-debug, and roughly 30 other curated skills are deliberately absent. This is a curation choice, not a gap; adding the source would be a separate decision about /command surface area.

Unchanged and still accurate: default_provider: anthropic, tool-mcp added, and hooks-streaming-ui / hooks-todo-display / hooks-approval / behaviors/logging.yaml dropped.

Also noted: upstream namespaces its roster as anchors:<name>; ours are bare because the definitions are vendored locally. Same six agents.

What is deliberately not changed

• CHANGELOG.md history. The five references in the v0.7.0 entry record what actually shipped. Renaming them would falsify the record. A new [Unreleased] entry describes this change instead.
• ## Behavioral Principles in context/system.md — that is the concept, and it is identical upstream.
• Incidental uses of the word "behavioral" in docs/CLI.md, AGENTS.md, and the new-feature skill.

Verification

Check	Result
./scripts/verify-wheel.py	PASS — all 6 checks against the built wheel, including the renamed bundle-name assertion
Zero stale identity references outside CHANGELOG.md	confirmed by grep
Frontmatter parses; 9 providers / 11 tools / 7 hooks / 6 agents intact	confirmed
All three self-referencing @mentions match bundle.name and resolve to files that exist on disk	confirmed — this is the failure mode the atomic group exists to prevent

Not yet run: a live session start confirming the principle block appears at the head of the system prompt. verify-wheel cannot cover it — it only checks that the file contains the declared name, never that the mentions resolve at runtime. The static resolution check above is the closest deterministic proxy. Worth one manual session before this leaves draft.

Impact

No wire-protocol change and no user-facing behavior change. The prepared-bundle cache key is (aaa_version, sha256(bundle.md)), so existing installs re-resolve once on next run — self-healing, no user action.

---

Release: amplifier-agent 0.16.0

This PR doubles as the release PR. RELEASING.md allows the bump to be folded into the change PR being released, and it is.

Artifacts

Artifact	Version	Tag	Released here?
Engine (amplifier-agent)	0.15.1 → 0.16.0	v0.16.0	yes
TS SDK (amplifier-agent-ts)	0.7.1 (unchanged)	wrapper-v*	no — wrappers/typescript/ untouched
Py SDK (amplifier-agent-py)	0.3.0 (unchanged)	py-v*	no — wrappers/python-py/ untouched

Engine-only. The root package.json (amplifier-agent-client-ts) is untouched, as required.

What is in the range

v0.15.1..HEAD — four commits, nine files:

• docs(skill): point the finish-release opencode gate at a check that exists #149 — docs(skill): finish-release opencode gate points at a check that exists. Repo-internal dev skill under .amplifier/, not shipped in the wheel, so no changelog entry.
• fix(bundle): drop descriptive prose from the system prompt #150 — descriptive prose removed from the head of the system prompt.
• The bundle rename and the upstream re-diff (this PR).
• The version bump and description trim (this PR).

PROTOCOL_VERSION is unchanged at 0.3.0 — identical at v0.15.1 and at HEAD. No cross-component coordination required. The amplifier-foundation git pin is also unchanged.

Version choice

Minor, not patch. Direct precedent: v0.7.0 was a minor bump for "Built-in bundle replaced ... bundle name all change". This release changes the built-in bundle's name and the content of every session's system prompt. No wire break, no removed flag, no envelope change, so not major.

Sweep

Clean — nothing removed. No plan/scratch/WIP files, no .log/.bak/.orig/.DS_Store, no absolute host paths, no internal URLs or session identifiers, no credential-shaped strings. No new print(...) on a CLI path (invariant #5). No new files under src/amplifier_agent_lib/bundle/, so the force-include invariant (#6) is not engaged.

Gate

Gate	Result
ruff check	PASS
ruff format --check	PASS — 167 files
pyright src/	PASS — 0 errors, 0 warnings
verify-codegen	PASS — spec.md + 32 schemas current
verify-wheel	PASS — 6/6 against the built amplifier_agent-0.16.0 wheel
verify-parity	PASS — 10/10 fixtures, Python and TypeScript runners agree
verify-wrapper	not run locally — bun is not installed on the release host. CI's TypeScript wrapper tests job covers it and is green, and wrappers/ is untouched in this range.

Beyond the standard gate, the rename was verified end to end in an isolated container built from this branch: the bundle resolves as amplifier-agent-anchors, @amplifier-agent-anchors:context/system.md resolves to the installed file, and a live model session recited all four behavioral principles — proving the system prompt reaches the model. That path has no fallback in _runtime.py, so it could not be proven statically.

Downstream: amplifier-app-opencode floor moves to 0.16.0

MIN_AGENT_VERSION goes 0.15.1 -> 0.16.0 as an adoption bump, so AGENT_PINNED_REF -- the exact tag opencode's launch-time self-heal installs -- tracks the current engine instead of drifting a release behind.

This is not a capability requirement. Nothing opencode consumes changed here: the HTTP face, GET /v1/models / /v1/skills / /v1/modes, host-config handling, PROTOCOL_VERSION, and the run stdout envelope are all untouched, and a code search across amplifier-app-opencode, amplifier-app-paperclip, and amplifier-app-nanoclaw finds zero references to the renamed bundle.

Adoption is the stated reason, and there is direct precedent: the current 0.15.1 floor was itself an adoption bump. prereqs.py says so in the ledger -- "0.15.1 is an adoption bump rather than a capability requirement: nothing here depends on what it changed ... The floor moves so AGENT_PINNED_REF ... tracks the current engine instead of drifting a release behind." The comment block for 0.16.0 will say the same plainly rather than inventing a capability that forced it.

Ordering is forced. AGENT_PINNED_REF = f"v{MIN_AGENT_VERSION}" resolves to v0.16.0, and prereqs.py performs uv tool install --from git+<repo>@v0.16.0 during self-heal. If the floor lands before that tag exists, every opencode launch tries to install a tag that 404s. The file states the rule itself: "to adopt a newer agent, bump both in one deliberate PR (after the tag is cut upstream)." So: merge this PR, push v0.16.0, and only then open the opencode floor PR -- which is exactly where amplifier-agent-finish-release-process Phase 4 puts it.

amplifier-app-paperclip and amplifier-app-nanoclaw caret-pin amplifier-agent-ts, which is not being released, so nothing propagates to them.

Merging does not publish

Publication is triggered by the tag, not the merge. After this merges, v0.16.0 is pushed from the tip of main, which fires publish-python.yml (PyPI) and release-notes.yml (GitHub Release). Since install.sh and amplifier-agent update resolve through the GitHub Releases API, the GitHub Release is what users actually receive.