progression-mood

name	progression-mood
description	Reliable techniques for darkening or brightening a chord progression — parallel-mode swaps, modal interchange (Phrygian / Aeolian / Dorian / Lydian / Mixolydian), and borrowed-chord substitutions. Use when a learner asks how to make a progression sound darker / sadder / moodier / brighter / more uplifting.
triggers	["darker","darken","moodier","sadder","melancholy","minor sounding","minor-sounding","brighter","brighten","uplifting","happier","borrowed chord","borrow from","modal mixture"]
license	internal
compatibility	{"agent-framework":">=1.0.0-preview","microsoft-extensions-ai":">=10.5.1"}
metadata	{"authoring-style":"deterministic-catalog","origin":"ported from Common/GA.Business.ML/Agents/Skills/ProgressionMoodSkill.cs (PR #71) — second canary for SKILL.md authoring","evidence-kinds":["catalog_lookup"]}

Progression Mood — Darkening and Brightening Techniques

Use this catalog when a learner asks how to shift the mood of a progression. Pick the darken branch when the query mentions darker / sadder / moodier / melancholy / "minor sounding"; pick the brighten branch when the query mentions brighter / uplifting / happier. If both intents appear, default to darken (it's the more common ask) and offer brighten as a follow-up.

Reproduce the technique list verbatim — the choice of techniques and their ordering is pedagogically validated.

Darken branch

Open with: "Here are five reliable ways to darken a progression. Pick one or stack them — each shifts the harmonic mood without abandoning the underlying key."

1. Swap to parallel minor — replace the tonic's major chord with its parallel minor (C → Cm). Pulls everything that follows toward minor-mode resolution.
2. Borrow from Aeolian (natural minor) — substitute IV → iv, V → v, and add chords from the parallel minor (bIII, bVI, bVII). Worked examples in C major:
   • C F G → C Fm G (the IV → iv move; standard pop-ballad).
   • C F G → C F Gm (the V → v move; weakens the pull home).
   • C Am F G → C Am Ab G — substitute bVI (Ab) for the original IV (F); the vi → bVI swap also works in this slot when the progression contains a vi chord.
3. Borrow from Phrygian — drop in bII (Db in C major) or use bII → I as a final resolution. The half-step approach gives a Spanish/cinematic colour.
4. Borrow from Dorian — keep the i minor but swap iv → IV (Dorian's natural 6) for the bittersweet, modal-folk feel of Scarborough Fair.
5. Replace V with bVII — C Bb F instead of C G F. Common in rock; the lack of a leading tone weakens the pull home and reads as moodier.

Close with: "Combine 1 + 2 for a strong sad-pop transformation; 3 alone for film-score gravity; 4 alone for folk melancholy."

Brighten branch

Open with: "Here are four reliable ways to brighten a progression that feels too dark or static."

1. Swap to parallel major — flip a minor tonic to its parallel major (Am → A). Strongest mood-flip available.
2. Borrow from Lydian — use a IVmaj7#11 colour, or substitute the II major chord (D in C Lydian) for the diatonic ii (Dm). The Lydian raised 4th gives a floating, dreamy lift.
3. Borrow from Mixolydian — add bVII as a passing chord that doesn't resolve down (I bVII IV I); rock-anthem brightness.
4. Reinforce V → I — make sure the dominant resolves cleanly back to tonic. Add a V7 or V/V to strengthen pull.

Close with: "Combine 1 + 4 for a definitive lift from minor to major; 2 alone for ethereal/cinematic brightness."

What this skill does NOT do

Do not attempt to transform a specific named progression on the fly (e.g. "darken C Am F G for me"). That requires position-by-position rewriting beyond a catalog answer — defer those queries to the LLM agent path with the catalog as background context.

Cross-reference

• C# implementation: Common/GA.Business.ML/Agents/Skills/ProgressionMoodSkill.cs
• Tests: Tests/Common/GA.Business.ML.Tests/Unit/ProgressionMoodSkillTests.cs