docs: add CHANGELOG and wire it into agent guidance

[giuliocalzo]

Summary

• Add CHANGELOG.md in Keep a Changelog format with release notes for v0.1.0, v0.3.0, v0.4.0, and an [Unreleased] section covering changes since v0.4.0 (including merged work such as node-observer API restart handling and pending node-data-broker main-container changes).
• Update AGENTS.md and .claude/CLAUDE.md to list CHANGELOG.md in the repository map, add a Documentation Impact Evaluation row for user-facing release notes, and extend the pre-push checklist.

Test plan

• Markdown-only change; no code or chart behavior affected
• Verified changelog links and section structure against git tags and GitHub releases

[greptile-apps]

Greptile Summary

This PR introduces CHANGELOG.md in Keep a Changelog format covering v0.1.0, v0.3.0, v0.4.0, and an [Unreleased] section, and wires it into the agent guidance files (AGENTS.md and .claude/CLAUDE.md) by adding it to the repository map, the documentation impact evaluation table, and the pre-push checklist.

• CHANGELOG.md: New file with per-version Added / Changed / Fixed / Removed entries and reference-style comparison links; the [Unreleased] section blends already-merged PRs with entries from PR feat(node-data-broker): run broker as main container with health probes #368, which has not yet landed on main.
• AGENTS.md / .claude/CLAUDE.md: Identical, correctly-synced additions pointing agents to CHANGELOG.md and instructing them to update [Unreleased] for user-facing changes.

Confidence Score: 4/5

The agent-guidance updates in AGENTS.md and .claude/CLAUDE.md are clean and correctly mirrored. The only concern is in CHANGELOG.md, where the [Unreleased] section pre-documents changes from PR #368, a PR that is not yet on main.

The node-data-broker main-container entries (new Helm values, probe config, migration table) all reference #368, which does not appear in the git log as of the current HEAD. Operators or tools reading [Unreleased] expect it to reflect what is actually checked in; including unmerged work risks premature Helm migrations or confusion about what the current codebase supports.

CHANGELOG.md — specifically the [Unreleased] entries for PR #368 and the accompanying Migration section.

Important Files Changed

Filename	Overview
CHANGELOG.md	New file introducing release history in Keep a Changelog format; [Unreleased] section includes entries for PR #368 which is not yet merged to main, causing the section to pre-announce changes not yet on the default branch.
AGENTS.md	Adds CHANGELOG.md to the repository map, documentation impact table, and pre-push checklist; identical to the .claude/CLAUDE.md additions and correctly kept in sync.
.claude/CLAUDE.md	Mirrors the AGENTS.md additions — CHANGELOG.md entry in repo map, new documentation impact row, and pre-push checklist item — all correctly matched to AGENTS.md.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Feature / Fix PR merged to main] --> B{User-facing change?}
    B -- Yes --> C[Update CHANGELOG.md\nunder Unreleased]
    B -- No --> D[No changelog entry needed]
    C --> E[PR pre-push checklist\nmake qualify + doc impact]
    E --> F[PR merged to main]
    F --> G{New release?}
    G -- Yes --> H[Move Unreleased entries\ninto versioned section\ne.g. 0.5.0 - date]
    G -- No --> I[Unreleased accumulates\nuntil next tag]
    H --> J[git tag vX.Y.Z]

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%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
flowchart TD
    A[Feature / Fix PR merged to main] --> B{User-facing change?}
    B -- Yes --> C[Update CHANGELOG.md\nunder Unreleased]
    B -- No --> D[No changelog entry needed]
    C --> E[PR pre-push checklist\nmake qualify + doc impact]
    E --> F[PR merged to main]
    F --> G{New release?}
    G -- Yes --> H[Move Unreleased entries\ninto versioned section\ne.g. 0.5.0 - date]
    G -- No --> I[Unreleased accumulates\nuntil next tag]
    H --> J[git tag vX.Y.Z]

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_{Reviews (1): Last reviewed commit: "docs: add CHANGELOG and wire it into age..." | Re-trigger Greptile}

[greptile-apps]

[Unreleased] pre-documents an open PR that hasn't landed on main

The entries referencing PR #368 (node-data-broker as main container, new port/refreshInterval/startupProbe Helm values, new CLI flags, the Migration table, and corresponding Changed/Removed bullets) describe code that is not yet on main. The git log confirms 0f94ca9 is the current HEAD and only #367 appears near the top — #368 is absent. Operators who read [Unreleased] expect those changes to be available in a checkout of main; pre-loading entries for an unmerged PR violates that contract and could trigger premature Helm migrations.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!